out of screen trace , (large -ve offset,wrong test voltage

[ShahRc]

Please check connection of the 2x5 pin-headers.

Tested 2x5 pin header connections between on the main board is fine against test points on the board.

Also tested connections from the second board to the test points and n the main board, all are connected.

Voltage readings on test points as follows;

av-,0.85v
v1,2.26v
v2,4.56v
v3,2.283v
v4,3.523v
V-,0.647
V+,8.18v

Still have the same trace error though..

[jye1]

AV- was not good. That should be the cause. Without the negative power rail (AV-) all voltages would shift up towards positive.

Please see viewtopic.php?f=19&t=1108 for troubleshooting.

[ShahRc]

AV- was not good. That should be the cause. Without the negative power rail (AV-) all voltages would shift up towards positive.

Please see viewtopic.php?f=19&t=1108 for troubleshooting.

Have checked the input to the ICL7660 volatge is the same with V+, output is however is not as per recommendation. Awaiting for replacement chip ..

[Dirkus411]

Did replacing the ICL7660 (U5 on the analog board) fix this issue? I'm having precisely the same problem, including a trace identical to what is pictured in the photos you posted. I also noted that the area of the ICL7660 was getting REAL warm. I've posted a youtube video here:

https://youtu.be/emQbAa2viEo

DSO Shell kit board number Q8uxNSyx, purchased from "ilastore-US" on Amazon.

[Dirkus411]

Should I break this out as a new topic?

[jye1]

Please try disconnecting the negative power supply from load by cutting trace as shown in the attachment. Then check if you can get V-. If V- restores that means there might be short with in the load. If V- still fails replace C11 and C12 respectively to see if V- appears. If not try replace U5.

[Dirkus411]

Thank you for the reply!

I cut the trace and still get incorrect V- and AV- values. I replaced C11 with another 100uf 16V electrolytic cap, but what is the value of C12?

*edit* I've also checked for shorts across C12 and C13, and they are not shorted. I also re-heated the solder on both of those components, and still get the same result.

[Dirkus411]

I've replaced C10 and C11, and verified that C12 is not shorted. I restored the cut trace with a jumper from the V- test point to the tab on U6. Replacing C10 got rid of the unusual saw tooth trace, and may have been the source of the issue. U5 still gets hot, but I think that's just a failure mode triggered by a possible issue with C10. My small multi-meter at home doesn't have a capacitance test mode, so I can't verify that C10 is failed aside from verifying that it's not shorted, but the fact that the fault changed when I swapped it out is encouraging. I'm trying to source an ICL 7660AIBAZ power supply IC for U5, but can't seem to find them in a reasonable quantity or available in a reasonable amount of time. Do you have them available for individual purchase? Perhaps as part of an analog board replacement kit?

Edit: I've also contacted the original poster, and he has not yet been able to correct the issue. Hopefully I can, and I would like to share this information with him.