Signal Cuts off after 5 seconds

[R.G.]

1. 8.42
2. 7.68
3. 4.4
4. 0
5. 8.8
6. 4.4
7. 8.4
8. 9

Pins 3 and 5 should be at half the voltage you measure on pin 8. And this should be the same as the voltage you measure on the junction of R2, R3, and R4. Notice that pin 3 may read a bit lower. But with pin 5 at 8.8v, no sound will come through. Also notice that pins 1 and 7 ... HAVE... to be at the same voltage, about half of the pin 8 voltage. It's clearly a problem where the right voltages are not getting to the pins.

I can't tell any more from this, but I think that there is a short across C6 and possibly C7, as well as miswiring of the controls.  For me to get any closer than that, I'd have to have the voltage to ground at each pin of each part.

Here's a trick: check the voltage on both sides of every cap. Where the voltage is the same on both sides, it's likely that the cap is shorted, either internally or externally by solder, or a wire. Not always, but a strong suspicion. If I had the schematic instead of the layout, I could tell you exactly which ones.

Check the voltage on both sides of each cap and post them back. It will tell us a lot more.

[vendettav]

ok I did what you said

I'll be posting cap voltages as X-Y (x being the first lug Y being the second)

C1 0-0.75 (first is the signal put side)
C2 4.46-0 (0 is the ground)
C3 9-0 (ground)
C4 8.85-0 (ground) (and so are the lugs of the resistors 8.85)
C5 8.33-7.50 (1st pin 2nd pin)
C6 7.63-0 (ground)
C7 4.42(IC pin 6) - 0 (the gain pot lug 3) I guess there's something wrong with this one?
C8 4.47-8.4
C9 8.4-0 (negative lug) I guess this is also wrong?
C10 I took out the tone control so no C10
C11 0-0 since C9 provides no voltage here

also here are fresh;y measured IC voltages
1 8.33
2 7.50
3 4.46
4 0
5 8.85
6 4.47
7 8.40
8 9

the 3rd digit might not be exact. my DMM keeps going up and down like 6-5-6-7-6 idk...

hopefully we can sort this out. I don't really want to completely redo the circuit the third time

[R.G.]

C1 0-0.75 (first is the signal put side)
The 0.75V is odd. I'd expect this to be higher, about half the voltage on pin 8 or across C3.

C2 4.46-0 (0 is the ground)
This one is OK, about half of the power supply.

C3 9-0 (ground)
This is the power supply voltage; it's OK.

C4 8.85-0 (ground) (and so are the lugs of the resistors 8.85)
Major wrong here. This point absolutely has to be about half of the voltage on C3. I am very suspicious that the soldering to R3 is not good or that R3 itself may be damaged.  In fact, given that this voltage is so wrong, it is an accident that the C2 voltage at 4.46 is about correct. There may be another problem there.

C5 8.33-7.50 (1st pin 2nd pin)
No additional information from this one.

C6 7.63-0 (ground)
Caused by incorrect voltage at C4, I think.

C7 4.42(IC pin 6) - 0 (the gain pot lug 3) I guess there's something wrong with this one?
Yes. If this was wired correctly, all lugs of the gain pot should be at about half the voltage of pin 8, and they should be set there by being the same as the voltage on pin 1. The voltage at pin 1 is wrong, so all pins of the gain pot should be the same wrong voltage if it was connected correctly. This is probably a second problem after the bias voltage being wrong.

C8 4.47-8.4
Problem caused by the bias voltage issue, I think.

C9 8.4-0 (negative lug) I guess this is also wrong?
It is, but it's "wrong" the right way for the set of other conditions. This may be correct when the bias voltage thing gets fixed.

C10 I took out the tone control so no C10
C11 0-0 since C9 provides no voltage here
Yep.

the 3rd digit might not be exact. my DMM keeps going up and down like 6-5-6-7-6 idk...

All digital instruments wobble a little bit in the lowest digit. this is an indication that the smallest bit of resolution is on the edge of tripping over from one digit to the next. It's an annoyance, but no indication of gross error.

So the capacitor voltage measurements tell us that there is something very wrong with R2/R3/R4/C4, and probably with R3. R3 is what "pulls down" on the voltage on R2, and it's not pulling down enough to bring the bias voltage down to the correct half-of-pin-8. Check every one of these resistor values, be certain they're correct, then measure them with the meter's resistance range to see if they're about correct (they'll read a bit low if still soldered in) and then check whether they're soldered in correctly and not damaged.

[vendettav]

I checked it all
so far R2 R3 R4 are connected. no resistance between their connected legs. all the other resistances are correct. R2 and R3 are 21.8 but that's natural.
shall I try swapping C4?

[R.G.]

I checked it all
so far R2 R3 R4 are connected. no resistance between their connected legs. all the other resistances are correct. R2 and R3 are 21.8 but that's natural.
shall I try swapping C4?

Is the ground-side lead of R3 - not the solder pad - connected to "ground" where the power comes in, and to pin 4?

[vendettav]

holy! how is this possible! 
i remember checking it yesterday.. all the way thru... now ive got the joint missing... hmm will solder it in like 30 mins or somethign. and post back. fiewf hope it'll help!

[vendettav]

ok igot it working.. only that fitting it into the enclosure again was another challenge.. .as always... anyways thanx guys hope when i re fit it it'll work good enough

[jefe]

holy! how is this possible!  
i remember checking it yesterday.. all the way thru... now ive got the joint missing...

See, you obviously didn't check everything "all the way thru". That joint didn't get up and walk away on it's own.  

I've never understood the attitutude where someone swears up and down that they've done everything correctly, but the circuit still isn't working right. If the circuit isn't working, then guess what.. you've done something wrong.

Anyways, glad you got it working. 

[vendettav]

ahh yeah i understand what you mena. btu i did clearly check it all. guess it's probably cz it's like a very tight fit for my enclosure and stereo pots (couldnt find mono ) ... I got it working btu when i put it in the enclosure now the volume pot isnt working the way it is supposed to! but that's easily fixable

thanx again!