BK Precision 875B LCR meter repair attempt

[henas]

I am looking for schematic for BK Precision 875B LCR meter or perhaps someone has some experience repairing them.
By mistake I connected nearly twice the voltage to its external power socket. Now, after turning the unit on, plus power rail is slowly floating down. In a minute or so the display starts showing low battery status. Minus power rail is OK. Steady -6 Volts. Without the schematic I can't see what regulates plus power rail. I can't see any regulator??
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[antimatter503]

You will probably be out of luck with finding a full schematic.
Have you taken the unit apart yet?
If you post good HQ pictures of the pcb, people will be much more likely to help.

EDIT:
You can trace out the board to find what regulates the positive rail by going backwards from input. It wont be far away in fact it really should be obvious. I highly suggest posting pictures. Also, probably not a good idea to continue powering the board when you know regulation is fried.

[henas]

Thank you for your time. Yes I agree it will be hard to get schematic but I searched archives and someone claimed on another blog he got one but it was more then 10 years ago.
I opened the unit. Nothing is visually fried. The unit has two boards and after disconnecting the second board the symptoms stayed the same so I suspect the problem is on the first board. It is the mixture off CMOS logic and a few TL061/062/27L2C op-amps. So far what I can see -6V is derived directly from the battery through -6V regulator and serves as negative rail for op-amps only. Battery plus appears to be connected directly to plus op-amps rail and serves as Vdd for CMOS I suspect, there is some circuitry somewhere which creates phantom  GND and possibly serves as Vss for CMOS logic. I checked some transistors and ICs for shorts. So far no success.
I will get some pictures as you suggested.

[henas]

Missing Ic is TL061 which I tested off circuit as inverting amplifier and nothing connected to offset pins 1 @ 5. It appears to be OK. Q2 is 3906 and Q3 3904 both tested OK on curve tracer.