Recent content by dsmart705

After having a closer look as the PSU (this was the only board that had any previous changes to it) I noticed most of the substituted parts were not correct. The cap values did not match the schematic and the transistor substitutes were not ideal. I was able to track down the original...

Good point about the filter switches, never thought about it that way. The pop is in both channels. The previous owner had already recapped the power supply board including all the diodes (original rectifiers remain for the power amp board) I did check all connections including original...

I had a look at the boards and could not see any cold joints but took the time to reflow anyways which did not solve the issue. After more testing it seems the only button that causes any noise is the Hi/Lo filter switch (specifically the "low" button). I get a slight pop when depressing that...

Hey Jeff, I didn't remove any ground during the recap but I did not spend much time inspecting all the original solder joints. I will give some attention to that and get bac to you on what (if) I find anything. The issue is certainly isolated to the front end of the amplifier. If I remove the...

I am on 60Hz AC power, not sure what the frequency of the hum is...sounds like 60Hz

I finished working my way through a TA 5650 which is now dialed in and functional but im getting a hum noise from the preamp. The amplifier stage is dead quiet but when the pre is connected the noise is there. It doesn't seem to be affected by any particular source or controls although I do get...

Just to round this thread out I installed the new resistor and all is well. Thanks again for the guidance as this issue had me baffled for quite some time. The best part about this is now I have room on the bench for a 5650 that has been sitting in the box for months.

You were right on the money. Pulled R326 and sure enough it was open....can't really explain that one as there is no visible issues with it. It was actually one of the few resistors in the general area I had not pulled to test but looking at the circuit again after your explaination it should...

Here is a list of voltages from the affected section. On both channels all caps have been replaced, double diodes, trimmers, fuse resistors, transistors other than Q304/Q307/Q309 and diodes other than D305/D306.

I'll do more testing and see what I can come up with. Thanks for the assistance on this

I had pulled and tested Q307 initially and it passed the test....I did not swap it, at that time, as I didn't have suitable replacement on hand (also I try to resist the urge to replace components unless they are known for failures. I just had a moment and actually swapped Q307 with Q304 (both...

Yes indeed, when I wrote out that post I had afew different thoughts going on all at once and write the wrong numbers down. The source voltage for both channels is +-82.5vdc and +- 46.5vdc. The other 2 voltage I had listed were measured on the gate and source of the output devices on the good...

Finally had afew moments to gather some voltages. Supply voltages are -+82.5 and -+46.5 on the problem channel (outputs removed) and I have -+56.6 and -+46.2 on the good channel (outputs are installed). Q310-Q308 have been replaced with with KSC2383 and KSA1013 which have been tested good...

Hmm, well this modification has already been done and my problem is still there so it must be from something else. I will have to take afew more meaurements and see if I can get closer to the source of the issue.

Their loss I suppose....