Replaced Nec C4082C opamp with TL072 and NE5532p's with OPA2134's and tested all other componets on the board before reinstalling board and retesting with same results. So apparently it isnt the preamp. on to the balance board I suppose.
Sounds like the volume pot is hooked up wrong at the very least. Usually no useful adjustment range on a log pot indicates "top" and "bottom" ends reversed.
Well more good news, cleaned balance fadar and now I have left channel and volume works great with left channel but still getting wide open volume on right channel if I barely turn volume knob and get loud background hiss noise. If I touch + pin of right channel behind volume control its like touching a turntable needle with amp cranked. does not do that on left channel + pin. So not really sure where to go from here?
I would think that too, but I was first person to service this amp and I haven't changed anything like that around. I put a picture up of the volume board you can look at and see what you think.
Thanks for your input though. appreciate it.🙂
Solved it, turns out the Alps volume pot is bad on right channel. Anyone know where I could find a replacement? Found Alps RK27 series 10KAx2 10K dual pot, but only has 25mm shaft length and need 35mm.
Thanks.
Thanks.
I wouldn't rush in declaring the transformer dead, they are fairly robust and
take some effort to kill. The primary does include a thermal(?) fuse, these have
been known to fail.
With amp powered off/unplugged, insert meter probes into the AC SWITCHED outlet at
rear and measure the resistance, this is a continuity check of the transformer primary.
"OL" would not be good, possibly that fuse. Primary windings wires are GREY, BROWN, ORANGE
and WHITE. Measure resistance between WHITE wire and one pin of the SWITCHED outlet. Repeat
for WHITE wire and other pin of switched outlet. Again "OL" would be bad.
Expect about 40Vac at transformer secondary. Worthwile to measure DC voltages at main caps
C702, C752 12000uf/63V and C701, C751 4700uf/63V. Measure at each pin of these caps, two of
the pins are connected and should read 0Vdc/GND. Expect about +/-58Vdc
@Itsme - just a heads-up on the Sony TA-F444ES - there's a TA-F444ES model, and a TA-F444ES II model - a lot of the non-flammable resistors in the earlier TA-F444ES model were changed to fusible types in the mk II version. It's quite possible there's already some fusibles in the earlier model waiting to catch you out sooner ot later... I repaired a mk II a few years ago, and found more than half of the fusibles had gone high.