A Question About A Front Panel Meter Problem: Pioneer SX-680

[RogerALB]

I have a thread elsewhere in this section about my SX-680 adventures, but this is somewhat more specific, so I figured that a new thread would be a OK. Here's the quick version of the issue:

When I turn on the SX-680 with the speakers connected but OFF the meters on the front panel ocellate a bit then go to about "half way", that is, just past straight up and down. This appears to be the 1w position, more or less, if I am reading them correctly.

When I press the speaker button to turn on the speakers the meters peg out all the way to the left and the front panel lights go off. My dim bulb goes to full brightness. Again, this is with the speakers connected.

I am working with the schematics and such, but I was wondering if anybody has encountered this or has any hot ideas as to what the heck is going on. My best guess is a short, but where? I have been known to guess wrong!

Many thanks for your comments and thoughts in advance.

R

 

[painttoad]

probably a blown stk.

When I turn on the SX-680 with the speakers connected but OFF the meters on the front panel ocellate a bit then go to about "half way", that is, just past straight up and down. This appears to be the 1w position, more or less, if I am reading them correctly.

that could be other components gone bad from collateral damage from the stk dying.

 

[RogerALB]

probably a blown stk.


that could be other components gone bad from collateral damage from the stk dying.

Oh, boy, that's what I was afraid of. Well, thanks for the tip! I will be doing a lot more testing, for sure.

 

[RogerALB]

UPDATE:

OK, well, this is a wild one. I have done a ton of checking and have been working on installing the caps and such from one of those "upgrade kits", and that has been a chore as most folks here probably know that the available schematics are really poor scans. Nevertheless, I proceeded onwards and upwards and finally found capacitor C335 which is harder to find that King Tut's tomb. I swapped that out and, in the process, discovered that one of the leads on the main power caps was badly soldered. Well, that was my bad, so I fixed it.

Now we have some positive action. With a source connected to AUX (or TAPE 1 or 2 for that matter) the and the speakers off the meters bounce around nicely just like you'd expect with the Bee Gees coming in. But, when I press the button to turn on the speakers the panel lights go dim, the dim bulb goes bright, and the meters drop to the far left as if they were dead, which I guess they are.

At this stage I am thinking there is a problem between the output of the STK modules and the speaker connections. What that could be I do not know ... yet.

And, by the way, a check of the STK voltages seem to be a little less weird than they were before, but I have to double check some stuff on that.

Many thanks for reading and commenting.