Photos of my TS1500

Discussions about Sinclair ZX80 and ZX81 Hardware
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Kahenraz
Posts: 25
Joined: Mon Feb 10, 2020 2:06 pm

Photos of my TS1500

Post by Kahenraz »

I received a Timex Sinclair 1000 that needed its keyboard matrix replaced. I snapped a few pictures of the terrible innards of my unit to share.

Internal board overview:
IMG_20200725_135842.jpg
Nasty flux all around this chip. Probably drag-soldered the pins:
IMG_20200725_135805.jpg
Heat from a soldering iron melted this keyboard ribbon connector slightly:
IMG_20200725_135643.jpg
Curious but impressive bodge work:
IMG_20200725_135743.jpg
More bodge work on the underside:
IMG_20200725_135627.jpg
Last edited by Kahenraz on Sun Jul 26, 2020 5:57 pm, edited 2 times in total.
Kahenraz
Posts: 25
Joined: Mon Feb 10, 2020 2:06 pm

Re: Photos of my TS1000

Post by Kahenraz »

Crystal is "secured" with double-sided tape that is barely attached to a capacitor. I pressed it down for the photo but the adhesive doesn't stick and it pops back up:
IMG_20200725_135614.jpg
Little wires on this part soldered directly into the board. Cool:
IMG_20200725_135727.jpg
Also. This unit doesn't work. :(
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Ed in SoDak
Posts: 24
Joined: Thu Jul 24, 2014 1:03 am

Re: Photos of my TS1500

Post by Ed in SoDak »

I wonder if that's factory rework? Replacing that big ULA would not be for the faint of heart, though there's many who could pull it off. I'm not in that group, lol.

Compared to the board in mine, it's not as clean as mine around the ULA. Mine does not have the flying lead on the underside, but that may be a production-line change. Mine has that resistor "via" same as yours. Sometimes on these complex, small boards a proper trace simply can't be laid out and a jumper is a must. None of that is too unusual for Sinclair or Timex.

Seems like many of these 1500s are dead in the water. Mine was the same way, a bad RAM chip plus a glass capacitor on the cassette interface and also a broken keyboard ribbon. With the help of my buddy Ian, we sleuthed it out and got it working.

If the ULA was user-replaced, it's possible one or more of the solder joints is dodgy or bridged. During the repair process on mine, I accidentally blew out a transistor. It may not hurt taking a closer look at the rework and verify voltages with a DMM.

Bad RAM can seem to be a video problem as the display can be all screwed up, if it even gets that far. So if you have a 16k pack handy, it might help eliminate a video problem.

One advantage with the 1500 is the RAM layout. If you plug in an external 16k pack, it will remap memory and happily boot from the external RAM, while the internal 16k is moved upwards in the memory map. You can at least use it that way as a 16k machine, though it's not as sleek and elegant as the console running on its own memory without a pack attached. But having the pack attached allows a little machine code/BASIC routine to be run that can read/write to the internal RAM and any errors can help determine which chip is bad.

Normally you'd POKE a new RAMTOP to combine the two 16k into 32k or some smaller amount, which would give you a "safe" space to store ML routines or just write or run a larger BASIC program.

If it's not bad RAM but a genuine video problem, next question is what TV/monitor are you feeding video to? Many LED screens just don't like the minimalist design of the Sinclair RF output. Most of the usual suspects for fails have been discovered and the cures applied, so it's just a matter of learning which fault is the culprit. Took a couple months before we finally figured out my 1500 but it was a great feeling when that cursor showed and it had a pulse!
-Ed
Spinnetti
Posts: 253
Joined: Sat Sep 12, 2020 11:29 pm

Re: Photos of my TS1500

Post by Spinnetti »

whatever happened with this? Hopefully you didn't sell it and I was the buyer, because I have a TS1500 now with no video lol. My board is identical except no jumper on the back. I did find a factory defect - cold solder joint on 1one of the 2 resistors that are cludged together on the topside near the port. I only get .2v at the video signal either at D19 or R20 Could that be ram chip? How do I identify a bad one without a rompack?

Thanks.
Zeddy: ZX80, ZX81/ZXpand, TS1000/ZXpand, TS1500/Zxpand+
Speccy: 48k, +, +2, +3, TS2068, "Bare Metal" Pi, Next KS2, IF1/Microdrives/Vdrive/Light Gun/VGA-Joy
QL: Minerva/QL-VGA/Custom PSU
C5: 24v, LiFE battery, Disc brakes
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