AMB Laboratories DIY Audio Forums

[krebob]

Hello
I put in another U2 chip and the results are the same.
7.6 volts dc from OV to B-
0 volts from UV to B-
I still get 7.6 volts from UV to B+.
Is this right?
I'm thinking it's time to build a new board.

Also, I have 2 sets of batteries from different sources and they are all running around 8.7 mm thick.

Thanks,
Bob

[amb]

7.6 volts dc from OV to B-
0 volts from UV to B-

It still shows an under-voltage condition. Are you using UCC-3911DP-3 (the -3 is important) for U2? Is your DMM accurate?

I still get 7.6 volts from UV to B+.
Is this right?

No.

I'm thinking it's time to build a new board.

Not so fast -- why not try charging the batteries with the χ1 to see if it will fix itself?

Also, I have 2 sets of batteries from different sources and they are all running around 8.7 mm thick.

Would they not fit in the case?

[krebob]

Hello

It still shows an under-voltage condition. Are you using UCC-3911DP-3 (the -3 is important) for U2? Is your DMM accurate?

Yes, it's the right ic.
My DMM is a fairly new Fluke. It should be close.

Not so fast -- why not try charging the batteries with the χ1 to see if it will fix itself?

I tried charging the batteries with the x1.
The led didn't light up and now I get 0 vdc from both UV and OV in relation to B-.

Would they not fit in the case?

I have 16.4 mm to work with and the batteries together measure 17.6 mm.
Thanks,
Bob

[amb]

I tried charging the batteries with the x1.
The led didn't light up and now I get 0 vdc from both UV and OV in relation to B-.

You need to reset U2 by installing the JP1 jumper shunt and then remove it. Try it again and see what happens.

I have 16.4 mm to work with and the batteries together measure 17.6 mm.

Hmm, then I guess you need to grind the board down a bit like what Coughinhk did.

[krebob]

Hello
I reset J2 and ended up back where I started.
0 vdc @UV and 7.6 vdc @OV
Repeated the process one more time with the same results.
Thanks,
Bob

[MisterX]

What are the battery voltages again?
Measure between the B- and COM test points and then between the COM and B+ test points.
I would also like to know what the voltages are on U2 pins 14 and 16 (relative to the VSS test point).
(double check's that you have installed the correct resistor values in the correct spots without pics)

[krebob]

Hello
Com to B- is 3.97 vdc
Com to B+ is 3.68 vdc
VSS to pin 16 voltage starts at 1.26 and then drops steadily and settles around 1.14
VSS to pin 14 voltage starts at 3.7 and drops down to .005
Is this my problem?
What is it?
Bob

[MisterX]

What are the voltage readings for U2 pins 14 and 16?
Relative to the B- test point this time..

I guess I should have asked for all of the readings in 1 message.

[krebob]

Hello
The voltage between pin 14 and B- is 0
The voltage between pin 16 and B- is 7.6
Thanks,
Bob

[MisterX]

What is the measured resistance of R5?
(you will have remove the batteries to measure it)