Onkyo TX-SV535 Dead

[ntehicks]

I just picked up this stereo receiver and was told it is dead. I opened it up and noticed the main fuse f901 looks blown. how would I test to see if there is a short on the other end of the fuse? thanks for your help with this.

[stj]

Re: Onkyo TX-SV535 Dead

proper-blown as we say in the u.k.


something is shorted.
so check the diodes,
rectifiers,
big transistors.

have you got a meter?
post a foto if you dont know how to use it.

[ntehicks]

Re: Onkyo TX-SV535 Dead

so I tested both sides of the fuse to ground and have no shorts there. I tested the 4 diodes and 2 small glass diodes next to the transformer and they test good. is it possible that this person connected some other device to one of the two power plugs on the back and that could have overloaded the fuse?

[Andrew F. Ali]

Re: Onkyo TX-SV535 Dead

Check the Output Transistors or perhaps this may have I.Cs on the output. And yes probably a heavy load was connected to the power sockets and overloaded the fuse.

[stj]

Re: Onkyo TX-SV535 Dead

have this:

[ntehicks]

Re: Onkyo TX-SV535 Dead

So as instructed I opened the bottom to test the output transistors. To my surprise 4 out of the 8 were un soldered and the leads were lifted. So I took my handy transistor tester and tested each one that was lifted. They were defiantly bad. I then tested each one that was still connected and they all tested good. I then tested each one of the 4 drive transistors and they tested good. I then put a fuse in the system and turned it on. The fuse didn't blow and the system turned on. So I think I will just need to replace the 4 finals and hopefully this receiver will be back to normal. The lady that gave me this said it just stopped working. I think she must have taken it in to have it looked at.

[artois7]

Re: Onkyo TX-SV535 Dead

Take a picture of the whole board for me from the top.

[budm]

Re: Onkyo TX-SV535 Dead

Did someone work on this unit before? it does not look like it was done from the factory.

[ntehicks]

Re: Onkyo TX-SV535 Dead

here is top view of this board.

[ntehicks]

Re: Onkyo TX-SV535 Dead

Yes I am thinking that the person I got the stereo from had to have taken it into a repair shop and they lifted the legs on the ones that were bad.

[ntehicks]

Re: Onkyo TX-SV535 Dead

so I replaced the 4 bad transistors. connected it to speakers to test it out. the system turns on but now goes into protect mode over and over. any ideas on where to check next?

[stj]

Re: Onkyo TX-SV535 Dead

whatever connects to the base pin of the new transistors.
because when the old ones shorted out they probably put upto 40v into the driver circuits.

[artois7]

Re: Onkyo TX-SV535 Dead

Check the white rectangle resistors on the channels that were gone. Should be 0.4 ohms across and 0.2ohms from centre pin to either outside pin on each resistor.