Pioneer SX 636 Stereo Receiver Repair - No Left Channel

Picked up a for parts/not working SX 636 with no left channel.

[@dannyyy1012]

I picked one up this weekend at a local thrift store and sadly found out that the left channel was out (or very weak sound) on that one as well but also sound comes through when volume is down! Furthermore the occasional deceased bulbs. Hoping to resurrect mine with care learning and looking at the video's from guys like you. Thanks for sharing, much appreciated

[@millervintagehifi3034]

Hope the video helps!

[@markeaton2003]

The head phone output should be checked for both channels, and the protection fuses on the back under a cover If they are good, then the output transistors should be good, then the driver transistors may be bad. There a 6 on the driver board that should be upgraded anyway. 2 to 2sc3503 and 4 to 2sa1220a.

[@millervintagehifi3034]

Thanks for the additional tips!

[@SDsailor7]

Did you have the output of the O'scope hooked to the input of the channel that is out?

[@millervintagehifi3034]

I had the test leads from the scope connected to different spots as I chased the signal. I use an old signal generator that I snagged for free for my test tones.

[@firmmomentum]

Think I have the same issue, but I have none of the fancy equipment to test. I have taken off top of the unit and will be replacing all fuses after cleaning but it looks like the board calls for several different types of fuses 2 -5a 125 v, 2 3a 125 v, and .5 a 125 v. I also. removed the fuses accessible on the back but can't tell rating of the two speaker protection fuses. Any insight. do I need to match up all the fuses or is there a universal fix

[@millervintagehifi3034]

No universal fix unfortunately. You would need to reference the service manual for the values of all of the fuses.

[@dvnoytekvlog6634]

Hello master 🙏👍

[@millervintagehifi3034]

Hello 👋

[@josephscerri2456]

I did not hear the relay click or it does not have on my 636 I don't hear it

[@millervintagehifi3034]

I don’t believe it has a protection relay.

[@markeaton2003]

there isn't one on that model.