T15 mishap

[digimax3]

I purchased and built 7 T15s, one of them I installed U5 and U6 backwards. When I initially tested the unit it worked, however not long. I noticed to power light dimming on the front of the unit. I turned the power off and inspected each unit and found the problem with U5 and U6. I ordered new parts and replaced them. I now have no audio output from that pre. The voltage is 18.05 and -17.98 I checked all the resistors they all seem to be fine.I checked the diodes and they seem to be fine. The T15 is a rev 1.4. all the other units are working fine. Any help would be appreciated.

[digimax3]

I have done some further testing I have no voltage on pin 5 of U2 and U4. I have checked and logged voltages on all the ICs. I have used a signal tracer and have no Audio on U1 pin 4 & 7, U2 pins 1,4,5,and 8, U3 pins ,1,2,3,5,and 6. U4 no audio on 4,5,7,and 8. The trim pot sounds scratchy when i turn it.
Voltage is
U1 1.-18.06 2.-17.31 3.17.85 4.18.32 5.-14.13 6.-16.90 7.18.05 8.-18.23
U2 1.-18.29 2.17.26 3.18.05 4.18.32 5.-011 6.15.33 7.-14.07 8.-18.05
U3 1.1.318 2.1.436 3.-.001 4.13.14 5.-18.32 6.-18.05 7.3.068 8.-11.26
U4 1.-17.80 2.13.14 3.-14.14 4.-19.32 5. 000 6.-13.14 7.18.05 8.17.80

Thanks, Gary

[tpryan]

Replace all of the ICs

[digimax3]

I replaced all of the IC's and it workes fine now.
Thanks, Gary