Trouble issue 6A

[yo3]

Hi guys, I need your help!
I bought faulty Zx+, issue 6A with many problems, the voltages on the board were not correct, I did a recap, I changed TR5-defective, zenner diode-defective, changed 7805 with Traco, I also found 7 out of 8 TMS4352 defective I replaced with: KM4164 (which were double tested and in Spectrum issue 2 and with the DRAM Tester) and at some point it worked, I had the startup logo
I wanted "bual-boot" and that's where the nightmare started (according to the saying: the best is the enemy of the good!).
I suspected low-ram, I unsoldered it and double checked in another Spectrum issue 2 and it works, as well as with DRAM Tester, I changed ULA6-7 in issue A- which had ULA5-3 and it works. I tested the integrated 74LS04 with Xgecu T-48 - it's ok
I also changed the Z-80 and it works, the only one I didn't change is the PCF1306P!
If I remove it from low-ram, the image on the monitor changes, if I remove it from upper-rom, nothing changes
I have:
ic13 (and all of the other 4116 chips too)
vbb (top left): -5,17V
vdd (bottom left): +12.14V
vcc (bottom right): +4.98V

voltage regulator
input: +11.55V
output: +4.99V
I am attaching some pictures
Thank you and best regards!

[sP1d3r]

Can you revert to a standard rom to check?

[1024MAK]

Those voltages are all okay.

The PCF1306P (also known as ZX8401 or Amstrad part no. 40058) are a common cause of faults in issue 6 boards.

They are obsolete and unattainable, but modules that perform the same function can be bought or made.

When using the normal Sinclair BASIC ROM does the border go white? If not, the Z80 is not able to run the ROM code.

Mark