Yamaha M80 - Help finding parts

amr2

Well-Known Member
Hello

I'm repairing an old Yamaha M80, one channel is in protect mode. A lot of components are broken...typical in this model. I have found some of the damaged parts, but I have problems with some of them. This is the list of the damaged transistors:

TR132,134: 2SC773 -> Found (used)
TR136,138: 2SA1169 -> Found (used)
TR120: 2SC3298 (B) -> Not found. Replaced by 2SC4793 (old stock)
TR126: 2SA1306 (B) -> Not found. Replaced by 2SA1837 (old stock)
TR118: 2SC3416 -> Not found
TR124: 2SA1352 -> Not found
TR116: 2SC1953 -> Not found


There are some generic versions (not originals) of TR118, 124 and 116 in ebay. Are these transistors reliable? or would it be better look for a modern replacement? Any suggestions are greatly appreciated.

Please excuse my poor English.
 
Welcome to AK

TR132,134: 2SC2773 -> 2SC3858 BDEnt,Digikey
TR136,138: 2SA1169 -> 2SA1494 BDEnt,Digikey
TR120: 2SC3298 -> 2SC4793 BDEnt ,Mouser,Digikey
TR126: 2SA1306 -> 2SA1837 BDEnt,Mouser,Digikey
TR118: 2SC3416 BDEnt ->KSC3503DS Digikey,Mouser
TR124: 2SA1352 BDEnt ->KSA1381ES Digikey,Mouser
TR116: 2SC1953 BDEnt ->KSC2690AYS Digikey,Mouser ->KSC3503DS Digikey,Mouser

See banner at the bottom of this page for BDEnt.
http://www.bdenterprisesinc.com/
http://www.mouser.com/
http://www.digikey.com/?WT.srch=1&WT.medium=cpc&WT.mc_id=IQ59985308
All reputable sources for transistors.

Last ditch choice would be NTE transistors and Ebay..
 
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Thank you very much. One question about this:

TR118: 2SC3416 -> KSC3503DS
TR124: 2SA1352 ->KSA1381ES

KSC3503DS have a lower hfe than KSA1381ES. Could be this a problem?
KSC3503ES seems to be obsolete.
 
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Another question, do you think it would be recommendable change these transistors in the channel that is OK, or leave the original parts?
 
Another question, do you think it would be recommendable change these transistors in the channel that is OK, or leave the original parts?

I would change them in both channels, but maybe this is just because I am a Libra...
 
Another question, do you think it would be recommendable change these transistors in the channel that is OK, or leave the original parts?

if it is working normally , do not touch anything .
Change the working channel is expensive and not necessary .
 
if it is working normally , do not touch anything .
Change the working channel is expensive and not necessary .

The output devices in the left channel of the A-960II I repairing at the moment died without any obvious reason and this caused a massacre in the driver stage. So I thougt it's a good idea to replace them in the other channel, too.
 
Right channel just repaired!

- Bias adjusted to 10mV. It seems quite stable, although decreases slightly when the amp heats up. The left channel doesn't decrease...

- With "Auto class A" on, bias is close to 120-130mv when the amp is cold. It decreases to 100mV when the amp heats up.

- Offset is about 20mv. The left channel is very close to 0. I have changed 2sk2389 and offset is now 10mv. I think this is acceptable.

It works, although not perfect...

Now, the bad news:

The left channel has broken :gigglemad After adjust the bias for 30min and check "Auto class A" mode, I turned off the amp. The fuses blows when I turned on the amplifier again (With "Auto Class A" off). Seems that the damage is only in the left channel:

TR111 (2SA1352): Base-Collector are shorted
TR131-133-135-137: shorted
R155: Opened

Fortunately, I have spare parts. I'm going to use KSA1381/KSC3503 as a subs for TR111-TR113, and 2SA1494/2SC3858 for the outputs. I think I'm going to change TR115 also (bias transistor 2SC1953, KSC3503 as a sub) and change bias pots for trimmers. Drivers and pre-drivers seems to be fine.
 
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Another issue. Power supply voltages:

HB: 95V (service manual says 88V)
LB: 42,5V (service manual says 48V)​

HB is higher than normal and LB is lower than normal. Any idea?
 
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Another issue. Power supply voltages:

HB: 95V (service manual says 88V)
LB: 42,5V (service manual says 48V)​

HB is higher than normal, and could be a problem at the voltage stage. And LB is lower than normal. Any idea?

What is your AC mains voltage ?
 
What is your AC mains voltage ?

Hello avionic

It's the European model, with a 220V/240V selector. Now it's set to 220V.
But I have just measured 243V main voltage!! Humm, I'm going to move the selector to 240V position and check voltages again...

Thank you.
 
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This is a very helpful thread! I have a similar problem to amR2's except I only found 2 bad transistors:
TR137: 2SA1169 -> 2SA1494
TR119: 2SC3298 -> 2SC4793
in the left channel, so since I'm using equivalent transistor, I know I should also replace the complementary pair for the substitute transistors:
TR133: 2SC2773 -> 2SC3858
TR125: 2SA1306 -> 2SA1837
The question is should I go ahead and replace the other matching outputs in the left channel:
TR135: 2SA1169 -> 2SA1494
TR133: 2SC2773 -> 2SC3858
By the way I think the failure was caused by corrosive migrating glue used to hold the big 1000uf caps on the main circuit board. I found Diode D119 and resistor R126 completely buried in glue.
Thanks!
 
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corrosive migrating glue used to hold the big 1000uH caps on the main circuit board
Would like to see that...

A 1000 microhenry capacitor...:rolleyes:
 
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