Old 02-21-2016, 04:11 AM   #1
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Default Rescued from Certain Doom!

Some of you know that I've recently moved my home and studio to a new location and am in the process right now of setting everything up.

There is a theatre here on the same site as my new home and studio that is currently unused which I will be actively involved in refurbishing. Once that is done, it will make a great recording space for larger projects. This theatre was designed well and has great acoustics and acoustic treatment. It is currently in a pretty sad state though and needs significant work to restore it but I have the time and the owner has the funds and the desire!!

Anyway, when I first started preparing my new home/studio for the move, I spotted a 19 inch rack cabinet sitting in the yard outside the theatre fully exposed to the weather. This rack was obviously the FOH rack for the theatre sound system because it contained a processor for the Bose 802 speaker system, a cassette deck, a radio mic receiver and a Yamaha P-2200 Pro Series power amplifier.

Upon spotting it, I immediately asked the caretaker what the plans were for this rack. He basically said to me, "It's stuffed!! You can take it and see if you can make use of it if you want," which I have done.

My main interest is the Yamaha amp and the rack. Those Yamaha amps have a very good reputation even to this day for sound quality and reliability. I've actually used them on the road touring in the past and they just keep going no matter what kind of harsh treatment they endure. Given that, I figured the amp itself is probably not "stuffed" but most likely works. Seriously, they are built like tanks!

I'm in the process of cleaning it up, checking it out for obvious faults and then powering it up and seeing if any of the special smoke contained in the components escapes!! I have a service manual for it and am qualified in electronics so I reckon this will be a decent win even if it does need repair.

I figured I'd make a post about it here BEFORE I power it up and post the progress for anyone interested to follow.

My plan is to use this amp with my Yamaha RX-V1800 which is currently running my Auratones and Crown subs in a 5.1 surround arrangement (actually 5.2 because the subs are currently in stereo). The 1800 has seven channels of amplification and I'm using five of those for the Auratones and two for the Crown subs. Once I have things set up here in my new studio space, I'll be running seven Auratones and the Crown subs in a 7.1 configuration and will need an extra two channels of amplification for the subs. The P-2200 will be a perfect fit for that need.

Here's a few before and after shots of the rack and the amp.

Amp rack


Closeup of Yamaha P-2200 before cleanup with 802 controller on top
Click image for full size view


Yamaha P-2200 after cleanup with RX-V1800 on top
Click image for full size view
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Old 02-21-2016, 04:45 AM   #2
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You seem to have done a great job cleaning it up. Apart from minor wear, looks like new. I'll follow what happens with it, let's hope no magic smoke escapes and it works. Did you do any recapping, any internal pics?
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Old 02-21-2016, 05:00 AM   #3
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You seem to have done a great job cleaning it up. Apart from minor wear, looks like new. I'll follow what happens with it, let's hope no magic smoke escapes and it works. Did you do any recapping, any internal pics?
I haven't taken any internal pics yet and haven't started the measurement process for initial obvious faults before power up yet either. I'll be doing that over the coming week.
I'll run my ESR meter over the caps and check them out. Chances are they will actually be OK. If not, it's a relatively easy job to recap things.

The most likely source of problems would probably be the bias trimpots if anything given this has been outside in the rain. Even then though, Yamaha built these things very robustly and I wouldn't be surprised if it works as is.

I will be taking internal pics and posting my findings as things progress though. This amp has one SERIOUS torroidal power supply transformer which takes up a fair chunk of the real estate inside.
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Old 02-21-2016, 05:05 AM   #4
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Yep, I bet those things were build like tanks. Will be interesting to see some pics and how it goes.
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Old 02-21-2016, 06:08 AM   #5
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Following this with interest.
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Old 02-21-2016, 06:42 AM   #6
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wow cool.
how fun.
hope you don't see any magic smoke come out of it.
I have a pre-amp that I replaced one of the tubes on (with a bad tube.......bah, humbug), and the magic smoke which came forth from my already expensive pre, cost me a pretty penny, for the repair.
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Old 02-21-2016, 06:45 AM   #7
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my 2€ on the Yamahas will work flawlessly. its from Yamaha!
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Old 02-21-2016, 06:46 AM   #8
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Following this with interest.
So do I!
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Old 02-21-2016, 07:07 AM   #9
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You have rain????
My grandad had never seen snow till he arrived in Europe during WW1.
From a station near Warrnambool....
"How ya gonna keep em down on the farm, now that they`ve seen the snow....."
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Old 02-21-2016, 11:45 AM   #10
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You seem to have done a great job cleaning it up. Apart from minor wear, looks like new.
Seriously... i thought that was an official product picture at first.
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Old 02-21-2016, 12:27 PM   #11
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I had one of the smaller P series amps years ago.
Fantastic reliability and the only amps we had that didnt also require sweeping the odd nut bolt or screw out of the amp rack occasionally.
They were not exactly new when we got them & they lasted up until when I left the UK for the USA. Wonder what happened to them?

And yes - very nice cleanup job! Fingers crossed the smoke didnt get let out.
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Old 02-21-2016, 02:17 PM   #12
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That's a very nice amp!

When you power it up for the first time, but a 100 W lightbulb in series. Give it a couple of minutes. Power down, let it rest for an hour or more. Repeat n times and make the power up period gradually longer.

That will prevent the big caps in the power supply (and maybe some others on the power rails) from shorting immediately, if this amp hasn't been used for years. The dielectric will rebuild itself and the caps just might be good.

If you put full power on them, they just might release magic smoke, killing the bridge rectifiers and the mains transformer if you're unlucky.

And put it upside down and open for drying. Else, some water might get trapped in there and take years to dry out. Rain water isn't bad, unless you have chemical plants in the vicinity. Then you have acid rain and that will eat away lots of stuff. But by the looks of it, it should be allright - no visible rust.

Do you plan to do the deck too?
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Old 02-21-2016, 02:36 PM   #13
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When you power it up for the first time, but a 100 W lightbulb in series. Give it a couple of minutes. Power down, let it rest for an hour or more. Repeat n times and make the power up period gradually longer.

That will prevent the big caps in the power supply (and maybe some others on the power rails) from shorting immediately, if this amp hasn't been used for years. The dielectric will rebuild itself and the caps just might be good.

If you put full power on them, they just might release magic smoke, killing the bridge rectifiers and the mains transformer if you're unlucky.
Good reminder cyrano, reforming the old caps gently instead of sudden charge. Have never managed to pop old caps myself so tend to forget this, then again I have usually straight out replaced the old ones. Since Dave has an ESR meter, that should also tell something about their condition?
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Old 02-21-2016, 03:21 PM   #14
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Following this, beautiful pics
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Old 02-21-2016, 03:56 PM   #15
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following with interest
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Old 02-21-2016, 04:32 PM   #16
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I would definitely open all the devices, check if there's any water damage inside.

It could either start a fire or destroy the whole device if there's any corrosion starting to set in.

And all the electrolytic capacitors should be replaced with good quality ones. They're old devices and electrolytic capacitors have a shelf life even if not used at all.

Happy refurbishing
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Old 02-21-2016, 06:06 PM   #17
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Originally Posted by xpander View Post
Good reminder cyrano, reforming the old caps gently instead of sudden charge. Have never managed to pop old caps myself so tend to forget this, then again I have usually straight out replaced the old ones. Since Dave has an ESR meter, that should also tell something about their condition?
ESR measurement is good, but you should also measure the actual capacity left and the leakage current. It's rare for a dried out cap to show a low ESR, but it can happen. In that case, the leakage current will be high.

And for the rest, I'm not a cap guru. I always wonder when I read about brand X being fantastic and brand Y being crap. Afaict, they all make good and bad caps and it's impossible to tell how long they'll last.

And some people swear that Russian high voltage caps destined for use with electrical motors, fi sound pretty good. I've never known any caps to sound better than the usual caps you can get at Farnell or Mouser. Of course, there is a difference between a ceramic disc type, an MKM and a polystyrene cap. And that is important if you're building a mic, a preamp or a filter. But as noise suppression electrolytics, I don't see any difference at all.

I've recently recapped a pair of 40 year old active Philips speakers. Some of the original caps were better than the new Panasonic caps, so I placed them back. These weren't in the audio path, or the filters anyway. And don't overdo it. Don't put a 150 V electrolytic in a 24 V power supply. It will just die sooner, because it can't keep it's dielectric in shape. A 63 V has plenty of margin there, even if the unloaded voltage goes to 48 V.

It's not unusual for an old cap to have increased capacity. That's when the ESR and leakage current will tell you if it's still good.

Increased capacity + high ESR or high leakage current = about to fail.
Increased capacity + low ESR and leakage current = still good.
Decreased capacity + high ESR or high leakage current = dried out. No way to tell if it will fail.

And when it comes to blowing caps, the worst are the safety caps on mains input. Some of these will blow some day, and they will make your workplace and the machine stink for days, if not weeks. I replace those without wondering if they are bad or not. Just to avoid them blowing a week after the repair.
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Old 02-23-2016, 11:02 AM   #18
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ESR measurement is good, but you should also measure the actual capacity left and the leakage current. It's rare for a dried out cap to show a low ESR, but it can happen. In that case, the leakage current will be high.

And for the rest, I'm not a cap guru. I always wonder when I read about brand X being fantastic and brand Y being crap. Afaict, they all make good and bad caps and it's impossible to tell how long they'll last.

And some people swear that Russian high voltage caps destined for use with electrical motors, fi sound pretty good. I've never known any caps to sound better than the usual caps you can get at Farnell or Mouser. Of course, there is a difference between a ceramic disc type, an MKM and a polystyrene cap. And that is important if you're building a mic, a preamp or a filter. But as noise suppression electrolytics, I don't see any difference at all.

I've recently recapped a pair of 40 year old active Philips speakers. Some of the original caps were better than the new Panasonic caps, so I placed them back. These weren't in the audio path, or the filters anyway. And don't overdo it. Don't put a 150 V electrolytic in a 24 V power supply. It will just die sooner, because it can't keep it's dielectric in shape. A 63 V has plenty of margin there, even if the unloaded voltage goes to 48 V.

It's not unusual for an old cap to have increased capacity. That's when the ESR and leakage current will tell you if it's still good.

Increased capacity + high ESR or high leakage current = about to fail.
Increased capacity + low ESR and leakage current = still good.
Decreased capacity + high ESR or high leakage current = dried out. No way to tell if it will fail.

And when it comes to blowing caps, the worst are the safety caps on mains input. Some of these will blow some day, and they will make your workplace and the machine stink for days, if not weeks. I replace those without wondering if they are bad or not. Just to avoid them blowing a week after the repair.
With all due respect Mr. Cyrano sir, why is it you've only posted six times on the DIY thread? From this post alone, I can confirm that your contributions there would be much valued!
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Old 02-23-2016, 11:56 AM   #19
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With all due respect Mr. Cyrano sir, why is it you've only posted six times on the DIY thread? From this post alone, I can confirm that your contributions there would be much valued!
I would really need to be a cat

Nine lives...

Most of the stuff I know, I know because of lots of experiments and then looking up answers to the questions they raise. Takes up a lot of time. And these area's are nothing but tiny specks in the universe of knowledge.

I know a bit about analog electronics stuff. I've built some mics, preamps and power amps, to a varying degree of success.

When it comes to digital, I'm just too old to take all of that in. Things are goin' too fast, for this old fart. Things like board design for digital, are way over my head. And soldering is no longer in it. Way too small components for my eyes and hands.

So when it comes to digital, I play with devices built by others, or CCB (Cheap Chinese Boards).

And Karbo, fi knows a lot more than I do. So do others. So I shut up and learn.

But I promise, when a question comes up about something I happen to know about, I'll be happy to reply.

And thanks for the compliment!
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Old 02-23-2016, 12:29 PM   #20
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And Karbo, fi knows a lot more than I do.
Not really honestly. You must have missed the beginning of the DIY thread where I was basically helpless. I have so many posts in that thread because I was using it as my documentation for what I was learning from everyone. I must thank beginwhereur for that thread because several offline friendships have sprung up due to its existence; his being one of them.

I do find it cool though that both you and I seem to cross multiple similar paths (music, recording, computers, programming, debugging, electronics etc.). Really cool since I surely don't have many peers outside the forum who cover that much ground - refreshing so thanks!
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Old 02-23-2016, 01:47 PM   #21
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You're being too modest, Karbo.

When I see your pedals, and your finishing of your "products", it's all very professional, really.

When I cut wood, or sheet metal, it's crooked every time. When I spray paint, there's always one runner, and so on...

And I did miss the beginning of the thread, somehow. I'm still too intimidated by Reaper's possibilities. Reading everything on this forum is humanly impossible and I've just recently learned how to select the right threads to read.

And lately, I have been building toys. Real toys, such as an electrical quad, for my 6 year old son. Driven by a 1 horse, 36 V electrical motor. With a speed and acceleration limiter and a real diff, to calm dad's nerves. He has succeeded already to breaks some stones in the garden wall, tho

The next project is a 3 wheel drive trike, cause he's getting too tall for the quad...

And now back to the Yamaha!

I'm curious to see if this thing has survived the rain.
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Old 02-27-2016, 10:04 AM   #22
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Great to see you guys here coming on board and eagerly awaiting the results of my tests and what transpires with this restoration. I honestly wasn't expecting so much interest so this is encouraging.

Update and photos are at the end of this post.
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Originally Posted by alanofoz View Post
Following this with interest.

Quote:
Originally Posted by chas51 View Post
wow cool.
how fun.
hope you don't see any magic smoke come out of it.
I have a pre-amp that I replaced one of the tubes on (with a bad tube...bah, humbug), and the magic smoke which came forth from my already expensive pre, cost me a pretty penny, for the repair.
Ouch! Tube circuits have that special high voltage secret smoke too. That stuff can be expensive and difficult to get back in once it gets out!
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Originally Posted by LightOfDay View Post
my 2€ on the Yamahas will work flawlessly. its from Yamaha!
That's my line of thought too and my hope for this amp.
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Originally Posted by ivansc View Post
You have rain????
My grandad had never seen snow till he arrived in Europe during WW1.
From a station near Warrnambool...
"How ya gonna keep em down on the farm, now that they`ve seen the snow..."
LOL
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Originally Posted by clepsydrae View Post
Seriously... i thought that was an official product picture at first.
That's one of my other great passions.. Photography. I spent way too much time setting up that shot to be honest! But it was fun.
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Originally Posted by ivansc View Post
I had one of the smaller P series amps years ago.
Fantastic reliability and the only amps we had that didnt also require sweeping the odd nut bolt or screw out of the amp rack occasionally.
They were not exactly new when we got them & they lasted up until when I left the UK for the USA. Wonder what happened to them?

And yes - very nice cleanup job! Fingers crossed the smoke didnt get let out.
That's pretty much my road experience with Yamaha gear too, hence my eagerness to rescue this amp.
There was a venue I used to do FOH engineering for a couple of decades ago that had an old M series console (the ones with the stepped input gain control switches) and it was starting to show signs of needing a service. Some of the pots and switches had started to get a little noisy but aside from that it worked well.
At the time, I was working as the head tech for the company that did the original install in that venue so I decided to pull the desk out and take it back to the workshop for a service.

Well....

When I took the covers off, I could hardly believe what I was seeing. Every board was coated in a thick layer of Coke, beer and Bourbon and some of the smaller components were obscured by that sticky, conductive mess!!! Nonetheless, the desk still worked with the only issue being the slightly noisy pots and switches!
I gave it a good cleanup, sprayed some Deoxit into the rotary pots and switches, pulled apart the faders and cleaned them and when I put it all back together, it worked flawlessly. I wouldn't be surprised if it is still working somewhere today.
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Originally Posted by cyrano View Post
That's a very nice amp!

When you power it up for the first time, but a 100 W lightbulb in series. Give it a couple of minutes. Power down, let it rest for an hour or more. Repeat n times and make the power up period gradually longer.

That will prevent the big caps in the power supply (and maybe some others on the power rails) from shorting immediately, if this amp hasn't been used for years. The dielectric will rebuild itself and the caps just might be good.

If you put full power on them, they just might release magic smoke, killing the bridge rectifiers and the mains transformer if you're unlucky.

And put it upside down and open for drying. Else, some water might get trapped in there and take years to dry out. Rain water isn't bad, unless you have chemical plants in the vicinity. Then you have acid rain and that will eat away lots of stuff. But by the looks of it, it should be allright - no visible rust.
You are thinking along the very same lines as me, especially regarding the dummy load. There's no way I would contemplate powering up an amp that had been left outside like this by plugging it directly into the mains!
The amp was already dry when I rescued it (it is summer here in Aussie land) and it is mainly just dirty with very little corrosion. It looks like the tape deck and 802 controller shielded it from the rain to a certain degree too.
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Do you plan to do the deck too?
Probably not. It is a pretty basic deck and I already have two much better ones in my studio which are in good working order.
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Originally Posted by xpander View Post
Good reminder cyrano, reforming the old caps gently instead of sudden charge. Have never managed to pop old caps myself so tend to forget this, then again I have usually straight out replaced the old ones. Since Dave has an ESR meter, that should also tell something about their condition?
ESR meters are very useful but there are other things such as leakage and, as Cyrano mentioned, changes in value and electrolyte condition.
Mostly though, if the original caps are decent quality, they are probably OK and within spec and Yamaha did use very good quality components in these amps.
Quote:
Originally Posted by gv.lazcano View Post
Following this, beautiful pics

Quote:
Originally Posted by Icchan View Post
I would definitely open all the devices, check if there's any water damage inside.

It could either start a fire or destroy the whole device if there's any corrosion starting to set in.

And all the electrolytic capacitors should be replaced with good quality ones. They're old devices and electrolytic capacitors have a shelf life even if not used at all.

Happy refurbishing
Cheers Icchan.
In some cases, the older caps should be replaced, especially if they were not high quality ones. However, replacing old caps is something that has become a default choice by many and it is not always beneficial. If the old ones are high quality (which these in the Yammy are), they are probably still well within spec and if so, they are probably better quality than many of the new ones. I have seen that so many times in good quality older equipment. Replacing old caps that are still good with new ones can actually DECREASE the performance of a device.
Quote:
Originally Posted by cyrano View Post
ESR measurement is good, but you should also measure the actual capacity left and the leakage current. It's rare for a dried out cap to show a low ESR, but it can happen. In that case, the leakage current will be high.

And for the rest, I'm not a cap guru. I always wonder when I read about brand X being fantastic and brand Y being crap. Afaict, they all make good and bad caps and it's impossible to tell how long they'll last.

And some people swear that Russian high voltage caps destined for use with electrical motors, fi sound pretty good. I've never known any caps to sound better than the usual caps you can get at Farnell or Mouser. Of course, there is a difference between a ceramic disc type, an MKM and a polystyrene cap. And that is important if you're building a mic, a preamp or a filter. But as noise suppression electrolytics, I don't see any difference at all.

I've recently recapped a pair of 40 year old active Philips speakers. Some of the original caps were better than the new Panasonic caps, so I placed them back. These weren't in the audio path, or the filters anyway. And don't overdo it. Don't put a 150 V electrolytic in a 24 V power supply. It will just die sooner, because it can't keep it's dielectric in shape. A 63 V has plenty of margin there, even if the unloaded voltage goes to 48 V.

It's not unusual for an old cap to have increased capacity. That's when the ESR and leakage current will tell you if it's still good.

Increased capacity + high ESR or high leakage current = about to fail.
Increased capacity + low ESR and leakage current = still good.
Decreased capacity + high ESR or high leakage current = dried out. No way to tell if it will fail.

And when it comes to blowing caps, the worst are the safety caps on mains input. Some of these will blow some day, and they will make your workplace and the machine stink for days, if not weeks. I replace those without wondering if they are bad or not. Just to avoid them blowing a week after the repair.
I know that smell only too well!!
I'm with you for the most part regarding what you've said about other caps here too. There are many myths about it being a must to replace every electro in sight these days. I have a room full of vintage analog synths and I have not replaced a single capacitor in ANY of them!
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Originally Posted by beginwhereur View Post
With all due respect Mr. Cyrano sir, why is it you've only posted six times on the DIY thread? From this post alone, I can confirm that your contributions there would be much valued!
I most heartily second that!!


OK, time for an update....

I still haven't had time to give this amp a good internal cleanup and fire it up yet. I've been busy with unpacking and sorting through everything after my house move and am in the process of configuring and installing my security system which is highest on my priority list right now.
I did get the workshop set up though and my security system is currently occupying all the space there.
Having said all that, I have taken a 'before' pic of the inside of the amp and have taken a shot of the workshop too so here's the pics....

Electronics workbench with security system undergoing configuration and testing
Click image for high res:


Yamaha P-2200 inside 'before' shot
Click image for high res:
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Old 02-27-2016, 10:07 AM   #23
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And lately, I have been building toys. Real toys, such as an electrical quad, for my 6 year old son. Driven by a 1 horse, 36 V electrical motor. With a speed and acceleration limiter and a real diff, to calm dad's nerves. He has succeeded already to breaks some stones in the garden wall, tho

The next project is a 3 wheel drive trike, cause he's getting too tall for the quad...
...
I think the others would agree with me in being keen to hear more about these projects. IMHO, that sort of info would not be at all out of place in the DIY electronics thread but would only give it a greater interest factor with some very cool diversity.
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Old 02-29-2016, 10:13 AM   #24
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Yamaha P-2200 inside 'before' shot
Click image for high res:
Yow-- dirty!

I'm very interested to know your approach to cleaning off that kind of weathered, caked-on crud.

My first thought would be a soft-bristle paint brush lightly coated with De-Oxit, followed by compressed air, but I would still wonder if that's best.

Hopefully, the PCB traces underneath aren't corroded. . . .

BTW, I think that's the biggest xfrmr I've ever seen in an audio device!
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Old 02-29-2016, 01:18 PM   #25
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Yow-- dirty!

I'm very interested to know your approach to cleaning off that kind of weathered, caked-on crud.

My first thought would be a soft-bristle paint brush lightly coated with De-Oxit, followed by compressed air, but I would still wonder if that's best.

Hopefully, the PCB traces underneath aren't corroded. . . .

BTW, I think that's the biggest xfrmr I've ever seen in an audio device!
Yeah. The power transformer is a whopper for sure. The main supply rails are +-80vDC.

As bad as it looks, the dirt isn't that badly caked on. I'm thinking most of it will be removable with a decent air compressor. I don't have one but I'm sure someone around here will have one I can borrow.

There's good news regarding the whole issue of recapping things, there are actually only two electrolytic capacitors in the whole audio path per channel. One is the input decoupling cap which is a 100uF and the other is the negative feedback cap which is 470uF. The rest of the circuit is direct coupled which no doubt contributes largely to the reputations these amps have for sound quality.

Their frequency response and power bandwidth goes right up to 100KHz (-1dB) and total harmonic distortion figures are around the 0.002 percent mark at 200 watts output into 8 ohms with both channels driven. Not bad for a design nearly 40 years old!! Actually, those figures are impressive even by today's standards!

Both of the caps are most likely well within spec too. They are good quality components and those values tend to be pretty resilient. Besides, they would be hardly working given that they are only passing low level input signals and negative feedback.
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Old 02-29-2016, 02:02 PM   #26
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I would open all the screws to get any moisture and other crap that's gotten in to the threads, out of there and from the holes. Otherwise it might start to rust over time and can cause some serious problems.

Especially when it's that dirty

About those caps... well good quality capacitors are expensive as hell. Only one I'd recommend for something like this would be genuine Nichicon's, and oh boy, are they expensive.

But you decide for yourself of course
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Old 02-29-2016, 04:36 PM   #27
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... and judging by the size of those heatsinks man, you will need to make sure those power transistors are making good clean contact with new thermal paste - I bet the weathering has taken its toll there - last thing you want is fried power transistors :-)

I'm sure those things run HOT!

Watching with interest - looks like a fab project - always nice to restore something back to new - been doing the same with beaten up AW16G's!

dB
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Old 03-01-2016, 06:04 AM   #28
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Or maybe: doomed in to certain rescue?

Nice find!
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Old 03-07-2016, 10:15 PM   #29
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Icchan and Dr Bob, some good suggestions there guys regarding screws and power transistors.
The amp is bone dry inside now but a little WD40 on the screws has already been applied to most of the threads. Great stuff WD40. No workshop should be without it.

MikComposer, nice rewording and yeah, I'm pretty happy with this find.

Quick update for everyone, I just purchased the parts to make a new switchable dummy load but i forgot to buy the globes!! Doh! Back to Bunnings tomorrow.
The dummy load will have six light sockets fitted with six 70 watt halogen 240v globes. It will also have six switches to select anything from 70 watts to 420 watts max load and will have two mains outlets. I'll post photos of it when it is built.

Oh, Dr Bob, you should make a post about your synth restorations. I'd be interested to follow your progress.
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Old 03-08-2016, 09:17 AM   #30
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I think the others would agree with me in being keen to hear more about these projects. IMHO, that sort of info would not be at all out of place in the DIY electronics thread but would only give it a greater interest factor with some very cool diversity.
Well, Dave, every time I do a project, I promise myself I'll take pictures, this time. And every time, I get so hung up in the project I completely forget...

I'll try next time.

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Quick update for everyone, I just purchased the parts to make a new switchable dummy load but i forgot to buy the globes!! Doh! Back to Bunnings tomorrow.
The dummy load will have six light sockets fitted with six 70 watt halogen 240v globes. It will also have six switches to select anything from 70 watts to 420 watts max load and will have two mains outlets. I'll post photos of it when it is built.
I hope you're using these light bulbs in series with the mains side of the power transformer and not to use them as a load on the outputs.

Lightbulbs have near zero resistance when cold. In a mains circuit, they'll heat up quick and go to their nominal resistance almost instantly.

On a speaker output, they'll trigger the protection circuit before they can warm up.

I think you probably know what you're doing, Dave, but just in case and for other readers...
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Old 03-08-2016, 09:37 AM   #31
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Oh, Dr Bob, you should make a post about your synth restorations. I'd be interested to follow your progress.
Still doing one at the moment. Hard to get the parts though ... seems Yamaha have run out of the "real parts" so will have to look for some ALPS alternative sliders.

The AW16G is a hard disk recorder! Next time I go inside, I'll do some pics!

dB
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Old 03-08-2016, 10:32 AM   #32
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Well, Dave, every time I do a project, I promise myself I'll take pictures, this time. And every time, I get so hung up in the project I completely forget...

I'll try next time.
I've been there many times myself too. Having a decent camera on my current phone helps though for times when the dSLR isn't at hand.
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I hope you're using these light bulbs in series with the mains side of the power transformer and not to use them as a load on the outputs.

Lightbulbs have near zero resistance when cold. In a mains circuit, they'll heat up quick and go to their nominal resistance almost instantly.

On a speaker output, they'll trigger the protection circuit before they can warm up.

I think you probably know what you're doing, Dave, but just in case and for other readers...
Yep. Agreed on all points. This dummy load is a 240 volt mains load which goes in series with the DUT (device under test). In this case, the primary of the power amp mains transformer.
I also have a microwave oven here to fix for a friend. It trips her mains house breaker when she starts it. I'll be using the dummy load to do that repair too. That one is probably a high voltage diode short (a common fault in microwave ovens).
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Old 03-08-2016, 10:39 AM   #33
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Still doing one at the moment. Hard to get the parts though ... seems Yamaha have run out of the "real parts" so will have to look for some ALPS alternative sliders.

The AW16G is a hard disk recorder! Next time I go inside, I'll do some pics!

dB
Oops yeah of course. I was thinking of the TX16w sampler.
Have you looked in ebay for those sliders? My DX7 has a volume slider issue at the moment and I haven't yet found a replacement for that one either. Last time it had a fault, it was with the data entry slider. It turned out that I had an old telephone that had a speakerphone built in and the volume pot was the exact part Yamaha used in the DX7 for the data slider. Nice stroke of luck that time.

Looking forward to seeing some pics of your next ventures inside your recorder and your hearing of your source for the sliders.
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Old 03-13-2016, 06:02 AM   #34
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Just a quick update - I gave the amp a preliminary clean on the inside and most of the dirt was very loose and simply brushed off which is a good thing.

My security system is now installed and running so I now have time to finally get the amp on the bench and do a dummy load test. I'm planning to put the dummy load together tomorrow and will post the results and possibly a pic or two afterwards.
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Old 03-13-2016, 11:45 AM   #35
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Oops yeah of course. I was thinking of the TX16w sampler.
Have you looked in ebay for those sliders?
Yeah, tried fleabay, but not a lot of luck. The main issue is that they are designated as RS451111 series. They need to be 10k B-taper though, mono. Strangely the sliders I have from Yamaha say 10k-B on them (yet their packaging says 100k - humph!). I have metered them and they are 10k!

They are 60mm long with 45 mm track/throw. Also, the prong for the slider knob/cap is very short, like 5mm, whereas just about all the 451111's you find are 15mm high. Thought I would try to get "insulated" ones so I can saw them down to size (harder with the metal ones!).

Underside the connecting prongs are 2 one end and 1 at the other end (ie voltaqe end to end and then the second prong is the slider tap).

As far as I can tell they are only control voltages, so no audio actually passes through the potentiometers.

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Looking forward to seeing some pics of your next ventures inside your recorder and your hearing of your source for the sliders.
Will do when I find time and my eyes can focus. Need glasses, lots of light and a magnifier these days - gone are the days of building a synth back in the early 1970's! Oh the joys of resistor chains for the keyboard, military grade resistors and small trimmers for each note as well - and still the little b*****s don't stay I tune - but they did have character!!!!

dB
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Old 03-13-2016, 01:17 PM   #36
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(grin) Hairdryer syndrome!
Remember it well on my home made modular system back in the earlyish seventies.
Gave it away when we moved to the USA & then gave away a Korg M20 I bought out there when we returned in 1991.

*sigh*
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Old 03-26-2016, 02:54 AM   #37
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Yeah, tried fleabay, but not a lot of luck. The main issue is that they are designated as RS451111 series. They need to be 10k B-taper though, mono. Strangely the sliders I have from Yamaha say 10k-B on them (yet their packaging says 100k - humph!). I have metered them and they are 10k!

They are 60mm long with 45 mm track/throw. Also, the prong for the slider knob/cap is very short, like 5mm, whereas just about all the 451111's you find are 15mm high. Thought I would try to get "insulated" ones so I can saw them down to size (harder with the metal ones!).

Underside the connecting prongs are 2 one end and 1 at the other end (ie voltaqe end to end and then the second prong is the slider tap).

As far as I can tell they are only control voltages, so no audio actually passes through the potentiometers.
B taper is actually linear and is the easiest to find. If you can't find ones with the same pin configuration, you might have to get a bit creative!
The metal shafts are actually pretty easy to cut if you put the end in a bench vice with the cut position right at the edge of the vice. Then use the vice as a cutting guide.
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Will do when I find time and my eyes can focus. Need glasses, lots of light and a magnifier these days - gone are the days of building a synth back in the early 1970's! Oh the joys of resistor chains for the keyboard, military grade resistors and small trimmers for each note as well - and still the little b*****s don't stay I tune - but they did have character!!!!

dB
That reminds me of one of my first electronics projects. It was a DIY stylophone. Mine wasn't as fancy with the resistors though. I just used the closest 1 percent values so it wasn't super accurate!!
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(grin) Hairdryer syndrome!
Remember it well on my home made modular system back in the earlyish seventies.
Gave it away when we moved to the USA & then gave away a Korg M20 I bought out there when we returned in 1991.

*sigh*
I bet you're kicking yourself now over giving those away!! Your DIY modular would probably fetch some crazy money on eBay these days. Analog gear has gone through the roof in value recently.

Korg have reintroduced the MS20 into their range again now. It has mini keys though but also MIDI in as well as CV/gate.
http://www.korg.com/us/products/synthesizers/ms_20mini/
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Old 03-26-2016, 03:07 AM   #38
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Well, it is almost time to plug in the Yammy and give it a test. I've been busy over the last few days so only just got time to finish building my dummy load today.

Here's a pic of it and the schematic. There's seven incandescent globes in this design with six of them switchable and the seventh one always in circuit. It also has a bypass switch to remove the globes from the circuit if the initial test passes.
I've used a 100 watt globe for the permanent one and 70 watt halogens for the switchable ones. That gives me plenty of options from 70 watts to 520 watts.

I also have a Panasonic Inverter Microwave oven here that I'm repairing for a friend. The inverter chopper transistor and the main bridge rectifier in the inverter circuit failed (these microwave ovens use a switchmode inverter for the 4KV supply to the magnetron in place of the usual iron core transformer and large HV cap/diode arrangement). You can see the failed components and the edge of the inverter PCB in the upper left of the dummy load photo.

Dummy Load


Schematic
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Old 03-26-2016, 06:29 AM   #39
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Look forward to seeing the results of your efforts Dave.

I'm always amazed at how much equipment is simply ditched when it can readily be saved. I guess people are bewitched by new technology.


Regards


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Old 04-20-2016, 12:04 PM   #40
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Look forward to seeing the results of your efforts Dave.

I'm always amazed at how much equipment is simply ditched when it can readily be saved. I guess people are bewitched by new technology.


Regards


SR
Yeah. Lots of good stuff gets tossed away far too easily if you ask me. There's some gems to be found for those who have a thrifty eye.


Stay tuned. I finally got the insides cleaned up, did a preliminary check and plugged it in to my dummy load.

I took some more photos so I'm not going to say any more until I process the photos and upload them.
Let's just say the results have been..... Erm.... Interesting!!

Final report to come shortly.....
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