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directive0
March 28th, 2014, 08:30 AM
Hi there,

I just got this TS 1500, and I'm trying to get it working but I'm new to computers of this era so I need some advice.

Using a multimeter here is what I know:

-The power supply provides 9 Volts.
-The computer exhibits voltages internally, which (perhaps naively) suggests to me that the internal powersupply is functioning.

When I plug the computer into my >40" Samsung LED TV through RCA cable I get no signal; no change or static, just black. Tv says "weak or no signal". Using a NES coaxial adapter (just cause I had it lying around, I didn't think it would work) I get intermittent static on channel 2, unplugging the adapter changes the static. This forces me to assume that there is a video signal being produced, it's just too weak for my TV.

I am pretty confident with modifications (soldering, etc) and have tried looking around for how to mod this computer for Composite video like the zx80 or the zx Spectrum, but I can't find anything specific.

I am seeking advice from experienced users, or links to pages I may have missed.

Thanks in advance for the patience with my noobetry, and any assistance you can provide.

deathshadow
March 29th, 2014, 12:03 AM
Silly question -- where are you? Are you trying to plug a PAL into NTSC or vice-versa? Don't suppose you tried channels 3 or 4?

jltursan
March 31st, 2014, 07:25 AM
Also try setting the bright control to the max and check if you can see what you type. Some ULAs are know to generate a incompatible signal (very dark display is the symptom).

directive0
April 4th, 2014, 07:30 AM
Okay, so I'm in Canada (NTSC?).

I managed to get a scope and a friend who was a video tech to take a look at some of the output from this thing; the signal was as expected; it pushed video. I managed to get an old TV and a VCR and plug it in using a RCA->Coax adapter; on channel 2 I get a grey screen with no "K" prompt. Its just grey. Waveform shows no characters when we press buttons. I tried using a different power supply as the one I have is at ~11volts DC. At 9 volts I get some pretty strange video noise, so that's probably not it.

Tried reseating the chips, no joy there.

I should have taken pictures but I didn't. Basically I'm lost. No idea where to even begin to assess the problem.

I'm just wondering whether this is worth my time or if I should sell it forward as is. Either way I've learned my lesson and from now on I'll ask the seller to produce a picture of it operating.

jltursan
April 7th, 2014, 11:49 PM
My TS-1000, being very close to the TS-1500, also showed a light grey screen when connected. It turned out being simply an ULA incompatibility with the monitor, no ULA blowed or related faults. As you have already tested it on an old TV set, seems that your fault it's a bit serious than mine.

Have you checked the 4116 RAM voltages?

directive0
April 8th, 2014, 04:51 AM
My TS-1000, being very close to the TS-1500, also showed a light grey screen when connected. It turned out being simply an ULA incompatibility with the monitor, no ULA blowed or related faults. As you have already tested it on an old TV set, seems that your fault it's a bit serious than mine.

Have you checked the 4116 RAM voltages?

Thanks for responding.

Not having any idea where to get the nominal values I have not checked those voltages. Can you please provide me with a link to any kind of reference for these?

directive0
May 6th, 2014, 08:03 AM
I've been playing around with this thing long enough now. Can't get anything but grey screen. Time to move on.

If anyone wants a donor unit PM me and I'll see what shipping is like.

Ed in SoDak
July 20th, 2014, 08:13 PM
Sent you a PM, if you still have this and haven't gotten it going yet.
-Ed

vwestlife
July 21st, 2014, 07:26 AM
Modern flat-panel TVs are well-known to not like the signal put out by the ZX81 and its derivatives. Before giving up, try it with a CRT TV -- preferably an old one that shows static instead of blanking out to a blue screen when it can't detect a signal.

And just in case yours happens to be a PAL model (although I don't know if they ever made a PAL version of the TS1500?), try tuning the TV to UHF channel 34 (if it's cable-ready, make sure the TV is in "air" mode instead of CATV). British Sinclairs put out a signal on U.K. channel 36, which uses the same video frequency as American UHF channel 34.