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Type: Posts; User: Hugo Holden

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  1. Replies
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    974

    If you measure a range of IC pins with a...

    If you measure a range of IC pins with a micrometer you will find even though some DIL IC pins seem to look a little different they are very closely the same size, except some IC's came with tinned...
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    974

    Mike, It is very important to use nothing...

    Mike,

    It is very important to use nothing other than an actual IC pin taken off an actual IC, I just took one off a cmos IC in my junk box, cut it off close to the IC body, Clamped it so solder...
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    974

    As I mentioned in post #5, to deal with the...

    As I mentioned in post #5, to deal with the sockets requires that an IC pin is soldered to a wire to make a handle so the pin (never anything else of any other geometry) is inserted into each socket...
  4. For these faults , if you could attach a...

    For these faults , if you could attach a schematic of the monitor on one if your posts, it makes a huge difference to anyone trying to help you with the fault.

    As I recall from the monitor...
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    974

    I'm guess from what you said that you have wire...

    I'm guess from what you said that you have wire wrapped your pcb's with wire wrap IC sockets with the usual long rectangular pins. While the wire wrap itself is pretty reliable as a long term...
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    296

    It does appear that electronic surplus stores all...

    It does appear that electronic surplus stores all around the world are closing down, very few left in AU and NZ now. The kinds of places where you can browse and buy small amounts of components.
    ...
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    It looks like a heat sink was previously attached...

    It looks like a heat sink was previously attached to the top of that IC and what you are seeing there is the usual white thermal coupling grease. If that is the case, then the IC could possibly run...
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    It is much easier to help if you can post the...

    It is much easier to help if you can post the schematic of the particular monitor you are dealing with then also indicate where on the schematic you have tested it and how you have tested it.

    For...
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    I just looked at the monitor schematic. The...

    I just looked at the monitor schematic. The monitor has its own H scan osc. It will run with no H sync and no V sync input either. The V oscillator and H oscillator only synchronize to the sync...
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    Often devices with small coils and fine wire fail...

    Often devices with small coils and fine wire fail after time. Its usually due to the residual flux not being cleaned off the connection points internally at the time of manufacture. They can suddenly...
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    The hole on the upper part of the panel might be...

    The hole on the upper part of the panel might be for a power ON LED. There is a SOL on ebay that has a lamp in that position. It would also help hold the acrylic sheet and logos over that area at...
  12. yes it could be, but the slow motion of it means...

    yes it could be, but the slow motion of it means its changing over a number of frames too, the first move would be to look at the v sync on the scope and if that was stable, lock the scope to that...
  13. Wow, that is a doozy. Firstly, likely there is...

    Wow, that is a doozy.

    Firstly, likely there is nothing wrong with the video monitor, it is just showing you what signals it is being presented with. It is like a visual window, or a scope, that...
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    Dave, The only SOLs I have seen have the two...

    Dave,

    The only SOLs I have seen have the two piece cover, but that one piece one looks like a Processor Technology part to me, it has identical splatter style paint that they used. Its not a bad...
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    It can sometimes be hard to find genuine vintage...

    It can sometimes be hard to find genuine vintage old stock IC's, with all the fakes coming out of the far east.

    To get around this I have some trusted suppliers that often have very difficult to...
  16. It is almost certain that the resistor had the...

    It is almost certain that the resistor had the power supply across it, in other words feeding a dead short, to glow and burn up like that, otherwise something else would have likely heated up too,...
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    Thanks Mike, it had me a little concerned,...

    Thanks Mike, it had me a little concerned, especially since when I got the MM5204 module the clear windows were not sealed to light and I had wondered if they might have partially erased over the...
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    Solos rom question

    I'm in the process of building a replica personality module for the SOL-20 using 4 MM5204's.

    I have inspected the dump of a solos that came on a disc with a replacement personality module from...
  19. Ilpaninaro, I think Dwight and I are...

    Ilpaninaro,

    I think Dwight and I are distracting you from your current computer problem. We are just talking about the theory behind the capacitor and its circuit on the lower right of the...
  20. Though I think in this case there is only a small...

    Though I think in this case there is only a small voltage "window" where the capacitor is not effectively connected and there is no charge or discharge pathway. The equivalent circuit is close to a...
  21. Dwight, Off the topic of this thread (but...

    Dwight,

    Off the topic of this thread (but shouldn't matter as the OP's computer is fixed now) it is amazing what kind of interesting and oddball and sometimes downright brilliant circuits turn up...
  22. Dwight, As far as I can see with this circuit,...

    Dwight,

    As far as I can see with this circuit, maybe, the capacitor is charged by the transistors emitter current and would reach the peak value there, plus the average DC component there and...
  23. ...I should have said a 5A slow fuse after the...

    ...I should have said a 5A slow fuse after the capacitors are back to good order (I keep thinking of 230V systems) but as Dwight noted you should have a 5A fuse for 120V and a 2.5A fuse for 220V.
  24. One issue with these types of supplies is that...

    One issue with these types of supplies is that due to the massive capacity of the filter capacitors, at turn on there is a large initial surge current. The power transformer's secondary is...
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    It wouldn't surprise me if it was the IC being...

    It wouldn't surprise me if it was the IC being defective. It is a bit of a hard ask for the IC , without a heat sink, to fully vertically deflect the crt, it takes 3 to 6 Watts of power to do it,...
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