AU-999 TU-999 no left channel

[BostonBrian]

I have a Sansui TU-999 & AU-999 with four SP-2500. When I first connected some test wires, all four speakers worked perfect. Wanting to make clean wire runs with more permanent quality gauge wire, I disconnected and now suddenly the two Left channel speakers are not working? Turning balance all the way to the left, nothing. Turn to right, both working. Also, sometimes at 4:00 in the morning the unit just blasts almost like full volume for a moment. It’s so loud an so fast I rush to turn it down that I can’t tell if it’s the non-working speakers or another issue? That has only happened three or four times during the last week or two since reconnecting speakers.
I hooked up the headphones and after wiggling it a bit did hear out of both ears. No tape, or record player connected during any of this if that matters.

 

[AnalogueBen]

Hi,
If it weren't for the momentary full noise finding, then I'd be looking at the simpler things like tight connections at speaker posts and firm at the speaker outputs on the amp. There are always the common issues like dirty switches and pots that need periodic cleaning. Yet if sometimes it's randomly going full noise then I'd be asking myself if I should be sending it to a tech or do I have the ability to locate the fault myself, that's something only really you can decide.
Fortunately for both circumstances this is a reasonably straightforward model(s) to work on.

I'd start out with the unit off, rotate knobs, move switches all for about 20 of so times.
Remove and wipe the pair of pre/main jumpers and wipe with alcohol cleaner and replace.
Then hook up that test speaker, just one is fine for testing, in each L/R and A/B/C position to see what changes .
Even try running another pair of RCA leads to the tuner. See how all that goes.