Replacement transistors for a Yamaha P-2200

Thanks for all of your help avionic. I would have been lost otherwise.

Now that I know what to look for, I'll start checking the left channel and then put together a shopping list.
 
I recently acquired one of those cheap ESR / component testers that I saw mentioned here:

http://www.audiokarma.org/forums/showthread.php?t=596851

So I decided to use it to check the electrolytics on the right channel, and also those 22,000 uf caps.

Here's the results:

C101 (10v, 100uf) measures:
Capacitance: 50.36uf
ESR: 1.1 ohm,
Vloss: 3.3%

C106 (10v, 470uf) measures:
282uf
ESR: 0.34 ohm
Vloss: 1.0%

C110 (63v, 220uf) measures:
228uf
ESR: 0.03 ohm
Vloss: 0.8%

C116 (16v, 470uf) measures:
537.6uf
ESR: 0.01 ohm
Vloss: 1.3%

C117 (16v, 470uf) measures:
553uf
ESR: 0.05 ohm
Vloss: 1.4%

22,000 uf cap measurements:

left side:
29.59mf
ESR: 0.17 ohm
Vloss: 1.6%

right side:
23.8mf
ESR: 0.13 ohm
Vloss: 1.6%
 
Just finished checking the left channel. I checked all the same components as I did on the right channel. It's doesn't look as bad as the right channel.

There are two shorted outputs - one 2SA909 and one 2SC1586. Also, R156 is measuring 35 Kohms. It's supposed to be 0.47 ohms.

Before I put in my parts order, is there anything else I should check?

Is there anything else I should replace just as preventative maintenance?

I'm willing to spend the time and money to get this amp as close to 100% as is practical.
 
Just finished checking the left channel. I checked all the same components as I did on the right channel. It's doesn't look as bad as the right channel.

There are two shorted outputs - one 2SA909 and one 2SC1586. Also, R156 is measuring 35 Kohms. It's supposed to be 0.47 ohms.

Before I put in my parts order, is there anything else I should check?

Is there anything else I should replace just as preventative maintenance?

I'm willing to spend the time and money to get this amp as close to 100% as is practical.

Reguardless what they measure. I´d still replace all the small electrolytics.
 
In case anyone is following this thread, I am still working on this amp. I have been very busy at my job (60 hours a week) and various projects around the house, so I've only had a few free hours to work on this.

So far, I've replaced all of the small electrolytics, the driver transistors, and all of the defective parts mentioned earlier in the thread, except for the output transistors (which I still need to order).

With all the stuff going on this summer, it will probably be a few more weeks until I finish this (I know, I'm so close).

The 2SC1213A and 2SA673A came from B and D Enterprises. The package types are different from the originals in the Yamaha:

HAO7re7l.jpg


oHOF3Rzl.jpg


And the pin configurations are reversed from the originals, so I installed them backwards.

I hope these will work.
 
Hello

Be very carefull with pin configuration

see my picture if you have a doubt . This is true for both types

Double check all fuse resistors EVEN if they "look fine"
 

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Hello

Be very carefull with pin configuration

see my picture if you have a doubt . This is true for both types

Double check all fuse resistors EVEN if they "look fine"

Hi clinic-audio,

Yes, that's the pin configuration that I measured also. I installed the new ones accordingly. Thanks for the heads-up!
 
Wishing you the best with your repairs, these are great amps, well worth the time and effort your giving it, have owned one myself for awhile now, one of my favorites.
 
Well, we're making progress.

I finished replacing the parts, including the outputs, and hooked it up to the dim bulb tester – passed :banana:

The adjustment procedure in the service manual says:

1. Wait a few minutes after turning on power. <<<I waited 15 minutes
2. Adjust idle current so that voltage between test terminals CT ans PE becomes 10mV when no signal is present.
3. Confirm that voltage between E and CT is 0V (confirmation of midpoint voltage).

Here's the results:

Right channel:
CT to PE (idle current adjustment) is 10mV. <<<This adjusted easily, and it wasn't far off to begin with.
E to CT (midpoint adjustment) = 43mV. <<<The manual says it should be 0V

Left channel:
CT to PE (idle current adjustment) <<<measures 0V, and adjusting the potentiometer does nothing. Something is wrong here.
E to CT (midpoint adjustment) = 23mV. <<<The manual says it should be 0V

From googling “midpoint voltage”, I understand now that it is the same as “DC offset” that can be measured at the speaker terminals. I read the sticky about DC offset here at Audiokarma, and that tells me the DC offset measurements on my amp are acceptable, but not great.

Of course, I'm worried about why I am getting 0V when adjusting the idle current on left channel.

Anyone have any ideas?

BTW, I also hooked it up to a pair of sacrificial test speakers for a few seconds, and they did produce sound. I didn't notice any distortion, or any other anomalies.
 
Are you shorting (jumpers) the inputs to insure they are at zero? And I wouldn't be surprised if some of the trim-pots are shot.
 
Well, this is embarrassing...

There was a tiny solder bridge across two solder joints of TR115. I somehow missed this when I was checking things over the first time I put the unit back together :eek::eek::eek:

I removed the bridge, then was able to set the bias on the left channel to 10mV. Offset is still 23mV left channel, 43mV right channel. There's no way to adjust offset. Amazingly, the solder bridge didn't appear to cause any damage.

The the amp is currently hooked up to some test speakers and it seems to be running fine. I can't comment on sound quality until I hook them up to my good speakers.

I'm monitoring component temperatures with an infrared thermometer. Everything is staying cool.

I'm pretty confident that this repair can be called a success. :banana::banana::banana:

Many thanks to those who left comments and offered advice, especially Avionic. :beerchug:
 
Replacing TR101 and 102 in both channels with closely matched (Hfe) transistor may get you closer to 0.00 mv of DC offset. The higher the gains the better, matched of course. Might have to get 20 or more.

512-KSA992FBU

I get them in the TA packaged. Then check each one and write the gain numbers right on the tape.

BTW these are not A992's
 

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Replacing TR101 and 102 in both channels with closely matched (Hfe) transistor may get you closer to 0.00 mv of DC offset. The higher the gains the better, matched of course. Might have to get 20 or more.

512-KSA992FBU

I get them in the TA packaged. Then check each one and write the gain numbers right on the tape.

BTW these are not A992's

I'll give them a try. I see that they are only $0.15 each at Mouser when you order 10 or more.
 
Replacing TR101 and 102 in both channels with closely matched (Hfe) transistor may get you closer to 0.00 mv of DC offset. The higher the gains the better, matched of course. Might have to get 20 or more.

512-KSA992FBU

I get them in the TA packaged. Then check each one and write the gain numbers right on the tape.

BTW these are not A992's

Do you have a correlation between measured gain difference and resulting offset?

Not questioning that it causes it, just curious if you have noted a consistent relationship. For example, 2 point different in gain causes 10mv offset or whatever?
 
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