YuT666 Posted August 13, 2016 Share Posted August 13, 2016 Hi,well, i repaired some of my other Thomsons and now i got a TO8 with a cut power cord.Ok, i replaced the power cable and the suppression capacitor. I powered on the TO8 and and he brings up the normale red light, but i only get this noisy picture ... Strange, 'cause i don't know, where to start searching for the failure. The scart cable works with all my other homecomputers (the ones with a scart connector) and i get the regular +5V and +12V from the power supply.I little help would be great.Thanks & regardsTom Quote Link to comment Share on other sites More sharing options...
zmame Posted August 13, 2016 Share Posted August 13, 2016 I was trying to locate diagrams for this particular machine, couldn't find anything. I would recommend checking your output voltages at the pinout connector at the motherboard while under load (board connected). If you find any diagrams/schematics i would be glad to help. Quote Link to comment Share on other sites More sharing options...
zmame Posted August 13, 2016 Share Posted August 13, 2016 also you might want to try UV method too for trying to find faults.. it dose not work with all colours of boards but this one looks like it might work. here is a good tutorial on UV pcb inspection method. https://youtu.be/g0qTOLBhlVs i have had good success with this method when it can be used. 1 Quote Link to comment Share on other sites More sharing options...
JamesD Posted August 13, 2016 Share Posted August 13, 2016 Power supply, and clock crystal would be my first two guesses. Quote Link to comment Share on other sites More sharing options...
CatPix Posted August 13, 2016 Share Posted August 13, 2016 It's the answer you got on system-CFG I think? Quote Link to comment Share on other sites More sharing options...
YuT666 Posted August 14, 2016 Author Share Posted August 14, 2016 Thanks for your answers ... Yes, i'm on system-cfg too and i hoped to get some more solutions. You know ... more eyes, more brains ... more possible solutions. The UV method looks interesting, so i will check this one when i've repaired my broken power supply ... it falls of the table yesterday. Quote Link to comment Share on other sites More sharing options...
zmame Posted August 14, 2016 Share Posted August 14, 2016 (edited) that sucks Edited August 14, 2016 by zmame Quote Link to comment Share on other sites More sharing options...
zmame Posted August 14, 2016 Share Posted August 14, 2016 I was thinking to earlier you mentioned the outputs where 12v+ 5v+. If you figure out the pinout for the PSU ribbon cable i would strip back the wires on ribbon cable and solder in a old AT power supply or Micro pc PSU unit. De solder the ribbon cable at the board (if possible). you can use a ATX PSU too just have to make a switch to trigger it on. 1 Quote Link to comment Share on other sites More sharing options...
YuT666 Posted August 14, 2016 Author Share Posted August 14, 2016 Yes, that would be an idea ... I'm not so much into that electronic things like reading shematics and soldering complicated pcb stuff (i repaired some easier things), so i've to learn some more of that crap first. I've some older ATX PSUs in the basement. Quote Link to comment Share on other sites More sharing options...
carlsson Posted August 14, 2016 Share Posted August 14, 2016 Unless it draws terrible amounts of power, you might get away with one of those cheap standalone power supplies meant for powering hard drives, the kind that sells on eBay for $2 or so. A friend of mine has a Sinclair PC-200 where the power supply section of the mother had broken off, similar to yours. He carefully desoldered and bridged wires across the broken traces, and replaced with a smaller PSU that however was too big to fit the case. I traded him a $2 drive PSU (rated for 5V @ 2A + 12V @ 2A) which fits very well and apparently is enough to power a 8088 computer. Quote Link to comment Share on other sites More sharing options...
CatPix Posted August 14, 2016 Share Posted August 14, 2016 Oh there is those indeed! I was looking for a solution for out old computers, since using an AT/ATX PSU seemed overkill, and hooking two different supplies seemed too clunky. I think the Colecovision need a negative voltage too, but I guess you can add an inverter into the console in this case... Quote Link to comment Share on other sites More sharing options...
carlsson Posted August 14, 2016 Share Posted August 14, 2016 As for the Colecovision, I understand that you can mod it with different RAM chips to remove the requirement for -5V. Something like a Mean-Well PT-65A would also work, although it requires a case. Btw, we ran the PC-200 on said hard drive PSU for 8 hours and the power supply didn't get particularly warm at all, while you might fear overheating if you pull maximum power from a cheap (switched) device. Quote Link to comment Share on other sites More sharing options...
Osgeld Posted August 15, 2016 Share Posted August 15, 2016 (edited) Course if it is drawing an obscene amount of current causing the rails to droop and you hook up a beef cake to it it may fry Which would let you know where the problem is, in a bit of a violent way Last thing I would do is hook it up to an atx supply without current limiting (it would limit but at what, my computer supply can provide 30 something amps at 12 volts and it's only 650 watts) Edited August 15, 2016 by Osgeld Quote Link to comment Share on other sites More sharing options...
YuT666 Posted August 15, 2016 Author Share Posted August 15, 2016 Well, maybe this could be another possibility: Some guys used a Meanwell PSU ... https://www.reichelt.de/Power-Supplies-up-to-150-W/SNT-RD-35B/3/index.html?ACTION=3&GROUPID=7300&ARTICLE=137089&OFFSET=500&SID=11V03F36wQATMAAGskb@g38212397c5915f0973ca3a204b6dbce9&LANGUAGE=EN ... to replace a faulty Atari 1040ST internal power supply, which also needs 5V+12V. Or an original 1040 internal power supply, 'cause i've some for spare parts. Quote Link to comment Share on other sites More sharing options...
carlsson Posted August 15, 2016 Share Posted August 15, 2016 I saw from the other thread at system-cfg (after a round through Google Translate) that you're recommended to put back the old, linear power supply. As I understand you measured its output voltages before it snapped, I suppose that is not the real problem with your computer, so getting another power source would just skip the element of repair. For reference, the PT-65A that I mentioned above is rated +5V @ 5.5A, +12V @ 2.5A and -5V @ 0.5A. I downloaded the service manual for the Thomson TO8 and it says the computer will use 25W without expansions. There are plenty of schematics and documentation in both French and English in the service manual, including details how the PSU works but it doesn't say how the power consumption is distributed. I can only compare with different systems (e.g. a C64C is rated 15W, a two-prong VIC-20 is rated 25W) so perhaps those 25W would be divided as 5V @ 2A + 12V @ 1.25A? In that case, the switching mode HDD might be on the weak side. For reference, I looked up a service manual for the Sinclair PC-200, but it didn't say anything about its power use. Quote Link to comment Share on other sites More sharing options...
CatPix Posted August 16, 2016 Share Posted August 16, 2016 (edited) I asked on the System CFG forums, and the answer is there : http://dcmoto.free.fr/documentation/schemas/alimentation-to8.html 5V=1,7A 12V=0,18A Maybe those numbers are to be confirmed. Or the Thomson design is wasteful? The early TO7 machiens were know to get burning hot to the touch after an hour of use and some machines stopped working from overheating. The issue was solved on TO-7 lmodels, but it doesn't mean they improved it so much ^^ Edited August 16, 2016 by CatPix 1 Quote Link to comment Share on other sites More sharing options...
carlsson Posted August 17, 2016 Share Posted August 17, 2016 Hm yes, the 25W is on the primary side, not the effective power the computer will use. Quote Link to comment Share on other sites More sharing options...
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