No luck with my purchases

[Dukes909]

So I bought a "working" Timex Sinclair 1000 from the interweb, hopefully can use to test my non-working ZX81 (see previous post).

Plug it in, power it up and... black screen! Boooooo! But it is different than the grey/white screen on my Z. Maybe I can swap chips and come up with something working. Ok, start swapping chips.

Now into the TS1000 I start putting chips from my ZX81.
- Z80 - now I get an all grey/white screen - (putting the "new" Z80 in my old ZX81 I get a black screen that was prevviously grey/white.
- ULA - no difference (all grey/white)
- ROM - no difference (all grey/white)
Plugging in the 16k RAM module that "was" working on my ZX81 - all grey/white.

So all I can determine from this is that the ULA, ROM, RAM, and possibly the 16k module are bad, which seems like extremely bad luck. I think maybe I should go back to using an emulator....grrrrr.

Any ideas? I had to send my scope back to Siglent as it was freezing up, so I don't have access to that right now until they repair. I do have a logic probe, VM.

Cheers

[bola_dor]

A white screen with no cursor usually means ULA is working.. at least the video sync is being created.
Before concluding all the ICs are wrong please check them on the working board..
At least the Z80 was not working. But check it on the other board anyway. You may have something wrong with the board. First check all voltages on the ICs are OK. Then you can check al data and addres lines for continuity. See the pinouts at MAK1024 signature. Look for the ROM "functional" pinout at that post last page..
If you have an oscilloscope you can check other things..