Problem with older amp, maybe someone can help

[whateverman]

i recently found an old onkyo tx-61 "synthesized tuner amplifier" in my house. i believe it is from the 70's. believe it or not, it is still in mint condition and puts out amazing sound. there is only one problem.. no matter what i try, only the right speaker outputs are working.

it supports 4 speakers (front left and right, back left and right). only the front and back right work. i opened it up and all the connections are there and it looks like new on the inside (except for some dust). no broken capacitors, everything is connected properly, etc.

if i connect a speaker to the left outputs and turn the volume all the way up, i can just BARELY hear sound. i can't find a manual or really any info about this receiver online. anyone have any ideas as to what i can do to fix this? i will gladly give more information and/or pictures. i really want to get this working, it is a really nice receiver (i personally think it sounds better than my current onkyo tx-sr601).

 

[Seth=L]

First thing that comes to mind is a short of some kind, maybe a bad transistor. Maybe check the fuses make sure that none are blown or damaged.

 

[j_garcia]

Pop the cover off and clean out any dust completely. I had the same thing when I picked up a Pioneer 990 at a yard sale - the thing was in pristine condition, yet had a lot of dust inside and wouldn't play loud. I got some canned air and a couple of paint brushes and cleaned it out and it works great now.

 

[whateverman]

i checked the fuse and it is not blown. i also got some compressed air and blew all the dust out.. but no luck. i double-checked all of the connections inside and everything looks perfect. do u have any more ideas?

 

[Seth=L]

i checked the fuse and it is not blown. i also got some compressed air and blew all the dust out.. but no luck. i double-checked all of the connections inside and everything looks perfect. do u have any more ideas?

Do you know anyone that can run diagnostics on it for cheap or free?

Also, fuses may not appear to be blown sometimes. In order to be sure you must conduct a continuity test with a multimeter or put it in another circuit, such as in line for a speaker wire.

 

[whateverman]

i'll pick up a new fuse tomorrow. if the fuse was blown though, wouldn't the right speaker inputs also not work? why would it be just the left side that isn't working? i will probably bring the receiver back to college with me (i am majoring in electronic engineering.) yeah yeah i know, i should have had this problem figured out within 10 minutes.. but oddly enough i haven't had much experience with audio equipment (even though i love audio equipment. ironic isn't it?) or much outside of lab. basically through my education we focus much more on the design aspect rather than troubleshooting. i will definitely be able to check everything if i bring it into a lab with me since we have all kinds of fun equipment at our school.

 

[j_garcia]

You'll probably have to do a little more serious cleaning then. Sounds like a contact or trace on a board went bad. Take a look at the capacitors also, as they may have leaked or dried out and may need to be replaced.

 

[Seth=L]

If there is only one fuse in the entire receiver, that is not the problem. Some amplifiers have a main AC protection Fuse and two more fuses for each output channel.