Timex Sinclair 1500 problems

[nama]

I've had this machine for ages, but I've never had it working and I thought it was about time I try to give it a go.

I can tune the computer in nice a clear on my TV, but the image is just blank (white). Sometimes there is a kind of strafing flashing that shoots across the screen in repeating intervals.

I have uploaded an video here:

http://web.me.com/lord_philip/sinclair/Timex1500.html

Not much to see really.

I have replaced the CPU, tried a ZX81 rom in place of the Timex ROM (hoping they are compatible), and piggy backed some of the RAM with some spare 4116 chips. Nothing really changes. Tested the voltages. Haven't spent much time doing any of this thoroughly yet though, as this was just an initial pass at seeing if I could get it working quickly. I think I'll need to go back and perform these tests again and spend a little more time doing it.

Can anyone point me in the right direction as to what I should test next?

Cheers

Phil

[Neil]

Could the issue that you are experiencing have anything to do with the fact that the 1500 was designed to be run at 60hz and not 50? Thats the first thought that comes to mind when I read your post. Good luck.
neil

[nama]

Hi,
Well that could certainly have something to do with it. However, from memory I had no issues getting a TS1000 (I don't have the TS1000 anymore) working on one of my old B/W TV sets here in Tokyo. Tokyo power is 100v 50hz. Would the issue be the same for a TS1000 as a TS1500?

Cheers
Phil

[Bill H]

Did you ever figure this out? It does look like it could be the 50 hz, I do not think the 1500 can run at 50hz, where as the 1000 can technically since it was designed to do it from the start.

Bill H

[Andy Rea]

TS1500 Can run at 50hz with a patched rom so that the test for UK/US always returns the UK value, of course your TV needs to be able to display 50Hz too.

there is a solder bridge on the board marked 50/60 Hz but in my tests it seemed to have no effect.

the ts1500 is also quite happy to run with a ts1000 rom although i never tried it on the main board, just as an external rom, with the internal rom dusabled.

it sounds to me, either a RAM issue faulty chips or bad voltages, or but i hope not the timex ULA is buggered.

Andy

[Bill H]

I didn't know that Andy. I do know it can run with a ts1000 rom, I switched it once to test if it picked up on the internal 16 k on power up, I did. It also, I believe, allowed me to switch the tv channel holding the 3 and 4 key with the ts1000 rom on power up.

Bill H

[BrunoFlorindo]

Simon from the zx81stuff website was able to get it working in the U.K. I think he has an article about it on his website.