still trying to fix my onix a-120...

[miekedmr]

OK... as far as I can tell, I have replaced every broken component and all the soldering joints are good. The protect light still comes on on the side that had broken. The power transistors were Sanken A1386 and C3519, which were replaced with MJL1302A and MJL3281A. From what I read these are good replacements, but I was wondering if the protect circuit could be sensitive to the change? Other parts replaced:
1 D669A, 1 B649A, two 100ohm resistors 1% tolerance, 10uF 50V cap replaced with 10uf 250V cap
I don't know enough to do anything besides diagnose and replace individual parts, so any help would be greatly appreciated.
Do you think I could email Onix and get a schematic?

 

[miekedmr]

No one has responded to my posts...
No advice, nothing. I don't get it.

 

[anatech]

Hi miekedmr,
Yes, get the diagram. From a remote location, we can't see the circuit and therefore don't have a good idea as to the layout. We can not give advice without knowing what the circuit looks like.

If you can then scan the circuit, we can help you.

-Chris

 

[fiak]

Why don't you deactivate the protections.
Those divices are made for people not involved in electronics, e.t.c.
Anyway extra rellays degrade the sound quality.

 

[anatech]

Hi fiak,
No. Poor advice.

An output relay sounds better than a fuse. A fuse sounds better than flames. Insurance will not cover if they find equipment safety has been degraded or defeated.

We went over this in another thread. Never defeat existing safety precautions. I have over 30 yrs of service experience to back me up on that one.

-Chris

 

[fiak]

Hi Chris.
Since it is a matter of security,I accept your point of view.
-I have to do it anyway, it will be used against me-
Anastasio.

 

[Zen Mod]

advice from someone who repair amps (and similar #$%&***!) for a living:
when you are in that situation (selective replacements are not effective) replace all smaller active devices in that channel,also diodes;
trust me-in 90% of repairs ,that's fastest and most secure way.........

 

[anatech]

Hi choky,
It helps to look at the pretty picture sometimes too.

After you are burned enough times in service you recognise amplifier types. Given a choice I'll always look at the schematic if I can.

-Chris

 

[Zen Mod]

Hi choky,
It helps to look at the pretty picture sometimes too.

After you are burned enough times in service you recognise amplifier types. Given a choice I'll always look at the schematic if I can.

-Chris

 

[Leolabs]

Why not post the internal picture of it???

 

[socal50]

good idea

 

[miekedmr]

thanks for the replies.. I have been away from home for a while, but I will take some pictures of the internals in the morning, and I have emailed onix to try to get the schematic.

 

[miekedmr]

An externally hosted image should be here but it was not working when we last tested it.

the components marked in red are the ones which I found were bad and have replaced.

 

[anatech]

Hi miekedmr,
There is more work to do. I would wait for a schematic diagram.

-Chris

 

[clem_o]

On the bad channel, there's an area of the PCB (between the filter capacitors and the two resistors encircled) that looks a bit dark - burn area?

Cheers!

 

[miekedmr]

Yes, those two 100ohm resistors burned up badly. The capacitor that was replaced had exploded also. There were only two leads sticking out of the board where the cap had been.
I checked to make sure the traces still worked in the area of the burn.

 

[DoomPixie]

mabey try and swap the output devices fromt he good channel into the bad channel? mabey the amp dosnt like the replacements you chose would atleast rule that one out? or am i just beign stupid here?
Owen

 

[anatech]

Hi Owen,

Never, ever do that. It will usually guarantie you need to double your parts order.

I'll bet the bias transistor is gone and posiibly the protection transistors. We should be looking at a schematic rather than replacing things and hitting the power.

-Chris

 

[clem_o]

Agree with Chris - seems there are more transistors than what would normally be used, so a schematic would certainly be needed!

 

[miekedmr]

They were nice enough to dig this up for me. Funny that it's "Onix Electronics England" but there's Korean (I think) on the schematic. Oh well, doesn't mean it's not a good amp.
This is from the 2nd version of the amp, I have the first, but the only difference on the outside is the addition of a remote for volume, so not much should have changed circuit-wise.

An externally hosted image should be here but it was not working when we last tested it.