Plimsoul headache round 2

[Unclereaper]

This is the 2nd try at this circuit. The 1st worked but never sounded right and this one has no output. Build is correct but pins 6 and 7 on ic have no output. The left side of the board when probed has sound but nothing on the right of voltages are 1-4.3  2-4.3  3-1.9  4-0  4.3  5-4.3  6-6.9  7-8.6  8-8.6 All seem odd

[willienillie]

Got a schematic?

Have you tried a different IC?  The one installed appears to be a fake.  That might not be your problem, many of the fakes out there actually do work, but it's the first thing I would try.

[Unclereaper]

Tried a few what makes u think it's a fake?

[Unclereaper]

No schematic and also tried ne5532

[willienillie]

what makes u think it's a fake?

I can't be 100% certain, but the shape of Texas is pretty far off, and AFAIK the real TI parts used a circle by pin 1, rather than a half-circle between 1 and 8.  They may have done that both ways, I'm not a TI expert by any means.  But here's what I'm used to seeing:

[willienillie]

I see one wrong resistor, a 1K in place of a 150r, to the left of the IC.  That may not matter at all, depending on what it's doing in the circuit (that's where a schematic helps).  Either way, it's not the reason your voltages are so wacky.

The 470r just to the right of the IC is obscured in the pictures, can't tell if it's connected to pin 5 or pin 6.

A few cap values are wrong, but not related to voltage issues.  Looks like you have 300p in place of 33p, 22p in place of 10p, and 3xx? in place of 2u2 in the lower left corner.

The cuts look right, I don't see any shorts, but I could be missing something.

[Unclereaper]

All components are in the right place the resistor n cap changes are upgrades made to fix squealing and oscillation that worked last time. Shouldn't the ic pins 6 and 7 have output when probed? I CANT FIND anything feeding signal to the right side of the board and the only pot with signal is sustain.

[willienillie]

I found this schematic, not sure if it's fully correct.



If you have signal at the sustain pot, then you have output from pin 1.  That should connect to pin 5 via the 470r resistor.  Do you have signal at either end of that resistor?

[Unclereaper]

Yes there is signal on pin 5 but non others on the right of the ic

[willienillie]

Your voltages at pins 1, 2, 4, 5, and 8 look right.  Pin 3 is low, but could just be meter loading.  6 and 7 are high, I don't know why, maybe a short somewhere that I can't find in the pics.

I guess the next thing I would try is pulling the chip from the socket, and then checking DC voltages at the socket pins.

[Unclereaper]

No ic
.008
.008
1.9
0
.009
7.14
8.86
8.86

[willienillie]

Hey I think I found the 8-7 short.  This is under the chip/socket.

(click for more bigger)


The voltage on pin 6 is probably coming from 7, through 200k resistance.

[JerS]

Yep - small shorts like this are easy to miss. I always run an exacto knife through the "gaps" between strips just in case. I have been burned like this many times!

[willienillie]

I should have said "100k~200k resistance" but whatever.

[Unclereaper]

I did run a blade through it but I'll look again we just got hit with hurricane zeta and we've been out of power.

[Unclereaper]

Went over it where u said and it came alive thank you so much man it sounds great!