Long term P2200 restoration

dondoucette

Too Many Projects
I've been working on this P2200 for some time now, it originally was in horrible shape as it had been gigged for years by the keyboard player I bought it from.

I'm in the home stretch and have no interest in taking any shortcuts now.

The heatsinks on one side of this amp were smashed up pretty badly, I obtained a used set to replace. I have transistors out and cleaned them up, I have new compound and insulators and thought just for the heck of it I would test gain. I fired up my Sencore TF46 super cricket and the following is what I got.
image.jpeg

In the left column are the A909's and the right C1586's. Don't know what the gain was when the transistors were new but the spread now seems considerable.

My question; did Yamaha bother to do any gain matching or no. I have 12 of each spare transistors, should I bother to install some that are more closely matched or not bother.

Thanks for your time.
Don
 
All electrolytics replaced, chassis and faceplate straightened, damaged heatsink on right channel replaced with a decent used spare, pots cleaned, bulbs replaced.

59A7AF07-AC3C-4421-865B-039B97EE96A1.jpeg
2sa682 temperature detecting transistor, original on this channel was split open, replaced with a good used OEM.

934021FB-35DC-4372-8E2B-5F55200273A1.jpeg 1E4A32AB-C5B3-43E3-A006-344803ACDB3F.jpeg
Progress... its only been waiting 2 years.

A9982DDC-22F1-45FA-9A59-0BB349716BFA.jpeg
Done. (Sandblasted handles)

C7B77650-5AA6-4171-9FD2-DA6BC73C0938.jpeg
Now this one. Part of the chassis is broken and bent from being dropped, cord has been cut off.

Ill have a look for burned up parts, test the output transistors, check electrolytics for shorts/open, replace the cord and bring it up on the variac watching current draw and looking for dc at the outputs. If all goes well a partial resto is in order, nothing too crazy, just make it look ok and work reliably.
I’m rather enamoured with these old Yamaha’s, I’ve had 2 in my main system for a number of years now and i just can’t find fault with them.
 
Hello

I am also restoring two P2200, thread here.
2sa682 temperature detecting transistor, original on this channel was split open, replaced with a good used OEM.
The 2SA682 transistor attached to the heatsink is the bias transistor, not a temperature detector. Mine has the plastic slightly cracked, I replaced them with BD140, it has pretty close specs.
 
Hello

I am also restoring two P2200, thread here.

The 2SA682 transistor attached to the heatsink is the bias transistor, not a temperature detector. Mine has the plastic slightly cracked, I replaced them with BD140, it has pretty close specs.

View attachment 1297834
It was rather tongue in cheek based on the service manual. LOL!
Both right.. The transistor thermally tracks the outputs temperature and auto-adjusts bias as needed to prevent thermal runaway.
 
Got the bent and broken chassis piece replaced
0AA8BEBE-E272-4B9C-B1C4-09D8BAAE77EA.jpeg 02F6F37A-E582-433E-89FF-C515A3C47881.jpeg 36E108DE-CA97-43D0-9BA8-EE60005697A5.jpeg

The faceplate is also bent so I will attempt to straighten it but if I’m unsuccessful I have a spare that I’ve sandblasted that I need to paint. A friend on mine has been working on duplicating the color Yamaha uses for the logo so we can screen print on the faceplate.
C75861F6-11F6-42B9-9BFA-1A416960283A.jpeg

I have new electrolytics on hand to replace what’s in this amp. I was a little dismayed to see that digikey no longer stocks my favorite Panasonic caps, but I’ve found some nice nichicon alternates to keep on hand. I’ve also ordered up my favorite EPCOS power supply caps, i like to order these only as needed.

Amplifier modules look great, little dusty, but no heat damaged parts or heat damaged parts of the boards, in fact the caps look new, I wonder if this amp got damaged early in its life and was set aside with little use?

Looking forward to firing this one up, of course my amplifier addiction has me owning more amplifiers than I have use for, and these Yamaha amplifiers are a particular favorite of mine.
 
Epcos B41456B9229M or UCC E36D101LPN223TDB7M are good choices for power supply caps.
 
Yeah. The EPCOS is +/-20%, the UCC is -10%, +50%
No listed impedance on the UCC and lifetime is listed 2000hrs@85C
EPCOS seems an all round better cap, I don’t mind paying the extra for my amplifiers, if I repaired one for someone else it would be good to have a cheaper alternative.
 
Yeah. The EPCOS is +/-20%, the UCC is -10%, +50%
No listed impedance on the UCC and lifetime is listed 2000hrs@85C
EPCOS seems an all round better cap, I don’t mind paying the extra for my amplifiers, if I repaired one for someone else it would be good to have a cheaper alternative.
Ripple current on the EPCOS is 45A the ripple current on the UCC is 14.15A with a 7.8mOhm ESR. How much ripple current does the P2200 see in everyday use?
 
The P2200 parts list specifies a KBH-2504, I believe this is a 25A 400V bridge rectifier. @DeltaB based on your statement, the UCCs ripple could be exceeded causing them to overheat and wear out prematurely. Thanks for the response!
 
The P2200 parts list specifies a KBH-2504, I believe this is a 25A 400V bridge rectifier. @DeltaB based on your statement, the UCCs ripple could be exceeded causing them to overheat and wear out prematurely. Thanks for the response!
The P2200's rated maximum current is 11.5A, so I don't think that they would be overheating. It primary fuse is only 7A. Consult the Service Manual for specs.
 
Last edited:
11,5A@120V is the primary current at rated operation. It has two primary fuses, 2x7A
 
Back
Top Bottom