old onkyo receiver question

[silvercookie]

i figured maybe someone on here would know.

i found an old onkyo receiver that uses germanium transistors.

i also have been looking for replacements cause 2 of the 4 channels are blown.

i saw some at radioshack and was wondering if all germanium transistors were the same, and if i could just drop in new ones, or if i have to find ones with a specific voltage/wattage.

thanks for any responses

[Enzo]

You saw germanium power transistors at Radio Shack? I have a hard time accepting that.

[silvercookie]

yep i swear to god.
i just went today and saw them.

or atleast it looked like a germ transistor.

http://www.radioshack.com/product/in...ductId=2062614

[oc disorder]

Um maybe you better do some more looking
http://www.datasheetcatalog.com/data...0/2N3055.shtml

Unless R/Shack have been forced to produce their NOS germs
they were saving up because of the global catastrophe.....








just kidding ...Looks aint everything here.....its whats inside that counts..!

It would probably be eaiser to drop in some output modules using chips but it would depend on the power supply.
This sort of thing which sells in Australia
http://www.jaycar.com.au/productView...T&SUBCATID=557
but that needs a +35volts and a minus35volts power supply.
There are others that can run on a single rail but you would have to look locally.

[Enzo]

I think you are confused. Germanium transistors don;t look any different from silicon ones. 2N3055 is most definitely a silicon transistor.

WHy don;t you post the numbers on those transistors? If they say something like D424 or B555 on them, there is a "2S" that is understood but not printed. So a D424 is really a 2SD424, for example. B555 is a 2SB555.

I really doubt your amp has germanium transistors.

That transistor shape like in the Radio Shack picture - the cowboy hat with two pins sticking down - is what we call a TO3, or transistor outline 3. Many kinds of transistor come in that shape, germanium, silicon, MOSFET, triacs, voltage regulators, power op amps, and so on.

[silvercookie]

Um maybe you better do some more looking
http://www.datasheetcatalog.com/data...0/2N3055.shtml

Unless R/Shack have been forced to produce their NOS germs
they were saving up because of the global catastrophe.....








just kidding ...Looks aint everything here.....its whats inside that counts..!

It would probably be eaiser to drop in some output modules using chips but it would depend on the power supply.
This sort of thing which sells in Australia
http://www.jaycar.com.au/productView...T&SUBCATID=557
but that needs a +35volts and a minus35volts power supply.
There are others that can run on a single rail but you would have to look locally.

oh ok, ill read up some more then.

I think you are confused. Germanium transistors don;t look any different from silicon ones. 2N3055 is most definitely a silicon transistor.

WHy don;t you post the numbers on those transistors? If they say something like D424 or B555 on them, there is a "2S" that is understood but not printed. So a D424 is really a 2SD424, for example. B555 is a 2SB555.

I really doubt your amp has germanium transistors.

That transistor shape like in the Radio Shack picture - the cowboy hat with two pins sticking down - is what we call a TO3, or transistor outline 3. Many kinds of transistor come in that shape, germanium, silicon, MOSFET, triacs, voltage regulators, power op amps, and so on.

oh,
ok when i get home i will read the back of it and post up all the numbers.
thanks for the info.

edit; it is not amp amp, it is a whole receiver.
ill see if i have a picture of it.

[silvercookie]

sorry guys i got home to late, im too tired to look, ill do it first thing tommorrow.

there is to much stuff to move to open it up

[silvercookie]

ok i just looked,
here is what they say;

2sd427
all 4 of them of them say that

[Enzo]

OK< that part is obsolete, and not available from my front line suppliers.

But lets get some other things straight.

You say two of your four channels are blown? ON an old Onkyo receiver? Is this actually a quad channel receiver? Four separate power amps? That would mean at least 8 powr transistors.

Or do you have four power transistors?

This is important, because we can sub something like an MJ15015 for your 2SD427s, but we don;t want to mix them in the same channel. IN other words we would move good parts around so hopefully asll the bad parts would be uin one bad channel, then we replace ALL the power transistors in THAT channel with MJ15015.

[silvercookie]

OK< that part is obsolete, and not available from my front line suppliers.

But lets get some other things straight.

You say two of your four channels are blown? ON an old Onkyo receiver? Is this actually a quad channel receiver? Four separate power amps? That would mean at least 8 powr transistors.

Or do you have four power transistors?

This is important, because we can sub something like an MJ15015 for your 2SD427s, but we don;t want to mix them in the same channel. IN other words we would move good parts around so hopefully asll the bad parts would be uin one bad channel, then we replace ALL the power transistors in THAT channel with MJ15015.

well it has a A and B selection.

there is a left channel and right channel for A
and a left channel and right channel for B.

but there are only 4 transistors.

im pretty sure they are blown cause if i switch it from A to B it doesnt produce anything.
but also when i have it on A+B, no sound comes out of any of the channels.

[Enzo]

That is what I thought. You have a plain old vanilla stereo receiver. It has two channel, left and right. The A and B are just connections. A left and B left go to the same place. The switch just lets you select which ones are on.


Stick with channel A until it works. Once A works, I'd feel pretty confident B will be working too. On some amps if you select both A and B nothing comes out until BOTH A and B have speakers connected.

You have then decided those transistors are bad only because no sound comes out that side? There are many reasons sound may not come out. Many amps have individual fuses for each channel inside.

With four transistors, there is a pair for each channel.

Have you explored the possibility that a dirty "record monitor" switch could be the cause?


Are there "preamp out" jacks on the back?

[silvercookie]

That is what I thought. You have a plain old vanilla stereo receiver. It has two channel, left and right. The A and B are just connections. A left and B left go to the same place. The switch just lets you select which ones are on.


Stick with channel A until it works. Once A works, I'd feel pretty confident B will be working too. On some amps if you select both A and B nothing comes out until BOTH A and B have speakers connected.

You have then decided those transistors are bad only because no sound comes out that side? There are many reasons sound may not come out. Many amps have individual fuses for each channel inside.

With four transistors, there is a pair for each channel.

Have you explored the possibility that a dirty "record monitor" switch could be the cause?


Are there "preamp out" jacks on the back?

no there is no pre amp out on the back back.

there is just phono.
tape 1 record
tape 1 play
tape 2 record
tape 2 play.

[Enzo]

`Have you moved every switch on the panel just to see if any causes even a brief moment of sound to come out?

The question remains, did you actually do some tests to determine bad transistors or are you just assuming they are the problem?

[silvercookie]

`Have you moved every switch on the panel just to see if any causes even a brief moment of sound to come out?

The question remains, did you actually do some tests to determine bad transistors or are you just assuming they are the problem?

i have tried everything possible.
i thought that each channel had 1 transistor, hence 4 channels,
but it might just be a loose wire or a bad switch or something

[silvercookie]

anyone?