• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Repairing Onko M-501 Amplifier

Status
Not open for further replies.

gholt12

New Member
I have a older Onkyo Amp that I would like to try and repair.

When the amp it turned on, after a while, the left channel will either turn off or get a garbled signal out of the speaker. I will then turn the amp off and wait a bit and then try again. Both channels will turn on. Then it will repeat the above after a while.

I got a copy of the service manual, and I was wondering what tool(s) one would need to do the testing and repair of this amp. The main reason I want to do the repair is to learn, also they are pretty old, so it may not be possible to repair, but I would like to give it a go. So, any help would be appreciated.
 

bountyhunter

Well-Known Member
It sounds like maybe the bias point on one channel is drifting with temperature. It could be a bad component breaking down with temp or voltage. The only way to troubleshoot is inject signals at the various points in the chain and see where it gets screwed up. These kind of circuits are not real easy to diagnose.

The minimum tools would be a signal generator and Oscilloscope.
 
Last edited:

gholt12

New Member
It sounds like maybe the bias point on one channel is drifting with temperature. It could be a bad component breaking down with temp or voltage. The only way to troubleshoot is inject signals at the various points in the chain and see where it gets screwed up. These kind of circuits are not real easy to diagnose.

The minimum tools would be a signal generator and Oscilloscope.
Are those spendy tools. The reason I ask, would it end up being more cost effective to have an experienced shop do the repair, if the tools are quire expensive.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Are those spendy tools. The reason I ask, would it end up being more cost effective to have an experienced shop do the repair, if the tools are quire expensive.
They are expensive, particulalry a scope - however, they certainly aren't the 'minimum' required - a simple multimeter is all you need for most jobs like this, and they cost very little money.

However, regardless of what test gear you might have, it's your brain which does the work - you first need to understand how the circuit works, so you can figure out what's going wrong.
 

bountyhunter

Well-Known Member
Are those spendy tools. The reason I ask, would it end up being more cost effective to have an experienced shop do the repair, if the tools are quire expensive.
Honestly, the cost effective way is to chuck it. Power amps are orders of magnitude cheaper than they were back in the old days. You won't believe what shops charge to repair electronics.
 
Last edited:

shimniok

Member
Used analog oscopes can cost as low as $40 + shipping on that auction site.

Seems to me a perfect signal generator would be... your CD player or computer... hook it up and play a tune for pete's sake. :D

You don't need a precise sine wave to figure out where the signal stops. But if you did need a sine wave, you can make a simple sine wave audio oscillator without too much trouble or expense I should think.

If you're just going to chuck it, I'll pay for shipping to my house instead. :D

Michael
 
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top