Sinclair ZX80 / ZX81 / Z88 Forums

Discussing with other people I have discovered that at least some EU TV "can see" NTSC programs!!! I have tried with some of my TVs and my beloved fullHD dvbT2 LG TV could do the job (it's the same TV that "can see" a rev. 1 and 2 ULA in a very good way!!! Impressive!!!). Some photos: first picture!...

Ok. Thank you. The ZX80 is working. Sadly I remembered badly and my TV does not sync @ 60 Hz... but I have been able to see something. The most important thing is that the ZX80 seems to works and all keys are ok ("obviously" I have not been able to run anything). DSC_0001.JPG DSC_0002.JPG DSC_0003.J...

Yesterday I received the ZX80!!! It is branded ZX80 USA so I suppose is prepared for 60 Hz.
I have only one doubt (not solved looking over internet...). The ZX80 is like ZX81, right? 9V central+ 0.65A, right?

Hello, if I understand well, if D11 is present, the ZX81 is ready for NTSC (USA) while, if D11 is NOT present, the ZX81 is ready for PAL (EU), right? Only this mod? D11 should be here, right: Senza nome.jpg Another thing is that probably a 4k ROM ZX80 could be able to handle a 60 Hz screen but this ...

Dear All, I have bought a ZX80 from USA supposing the mod from NTSC to PAL would be simple, like it is in the ZX81... but, since I am not a real technician and the motherboard does not have the easy welding point like the ZX81, I am stuck. :( I am still waiting for the ZX80 so I am not able at the m...

Heppy to help!
Tell me the results!

Obviously the RAM is ok. Having no more ideas I have decided simply to change the two transistors and the two capacitors and... the ZX81 is not perfectly working! I have chenged them all together so I will never know if it was a cold welding and which component was the bad one. The strange issue is ...

Let's wait for the RAM chips and let's cross the fingers...

A faulty Z80 CPU, a faulty ULA, a faulty ROM or a faulty RAM chip could and would prevent start-up. A poor connection (socket, dry joint, broken/cracked track) in any of the many critical circuits could also prevent start-up. Mark The two transistors, unmounted and professionally tested, are good. ...

The transistors used in the ZX81 are fairly robust and failure of them is very, very rare. So unless you have a good reason to suspect them, my recommendation would be to leave them alone. Mark The ZX80A and the ROM are good since I have tested in the working ZX81. The resistors are ok (they are vi...