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Type: Posts; User: Dwight Elvey

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  1. Replies
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    Speaking of dark room. Make sure you are not...

    Speaking of dark room. Make sure you are not blasting the area of the sensor with a really bright, especially a incandescent light. The drive normally runs in a closed case. There is some...
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    Locating a capacitor shorted on a power rail is...

    Locating a capacitor shorted on a power rail is not the same as locating a faulty RAM or interrupt controller.
    Isolating the faulty power rail doesn't take much effort. Locating which is the bad...
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    I'm not sure how that leads one to the faulty...

    I'm not sure how that leads one to the faulty capacitor?
    Dwight
  4. [QUOTE=djones1960;614358] I spoke to Jeff...

    I spoke to Jeff about it. It seems he doesn't synch with the index. I explained to him how it needs to work but he'd have to change how he deals with it to keep track of the sectors. I looked at it...
  5. Hi A couple things that can help here. First,...

    Hi
    A couple things that can help here. First, make sure the punch parts are well aligned. Make sure the punch is sharp. It gets dull. Finally, make sure any burs are flat and not sticking out. I...
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    Check that the metal part that the disk rides on...

    Check that the metal part that the disk rides on is not swelled. If these were in a moist environment the pot metal hub can swell. If you put a disk on one of these it will damage the center. I've...
  7. It may be in a buffer some place. You might just...

    It may be in a buffer some place. You might just do a search to see if you can find it. It is possible that it is lost because some buffer space is reused that might have held it.
    Dwight
  8. It is like a disease. One person makes it work by...

    It is like a disease. One person makes it work by replacing a bunch of capacitors and it spreads to maybe 10 or 20 others.
    None of them, including the original one have no idea how to trouble...
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    It is clearly the keyboard. One wonders why they...

    It is clearly the keyboard. One wonders why they brought so many pins out. It may have been a combination keyboard and monitor data. I can't quite make out the letters on the chips to the right but I...
  10. The NC4000 implementation of CMForth would of...

    The NC4000 implementation of CMForth would of course need low level fixes for the RTX2000 parts. I don't think all of the bit fields are the same. Most of the operations are the same though.
    Dwight
  11. Once done replacing the capacitors, you'd need to...

    Once done replacing the capacitors, you'd need to actually trouble shoot the power supply. It is clearly a good idea to replace the RIFA anyway. As always, I'd recommend finding out what failed first...
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    I have to get back to working on the disk...

    I have to get back to working on the disk controller of my Nicolet. There is a board in it that has a several IC's that are flops, as I recall. Some don't have pullup resistors but are just floating....
  13. A rare one to look for would be the KTM-2/80....

    A rare one to look for would be the KTM-2/80. These were made by Synertek. They are typically an open PC board with keyboard attached. They require a standard B/W video 60Hz monitor and power supply....
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    It might be a SYM-1 or even a SYM-2 as well. The...

    It might be a SYM-1 or even a SYM-2 as well. The SYM-2 is small enough to fit into the space. The SYM-1 is a little large.
    Dwight
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    I have a rare Polymorphic keyboard with the same...

    I have a rare Polymorphic keyboard with the same affliction. If it is only one corner busted, careful snipping can remove part of the broken corner but the other corners are easily broken. Someone...
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    I don't think it was a keyboard. It was more...

    I don't think it was a keyboard. It was more likely a single board computer stuffed in a large generic keyboard case. Maybe a Commodore or similar.
    Dwight
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    I really depends on the length between drivers...

    I really depends on the length between drivers and receivers. Technically it is a transmission line problem. Still, in most cases, it is just replacing the typical pull up of the the circuit designed...
  18. To bad, it was looking like an interesting...

    To bad, it was looking like an interesting problem.
    Dwight
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    I enjoyed the hunt. Here and at work, I always...

    I enjoyed the hunt.
    Here and at work, I always try to clearly convey my thoughts, in a clear way. It is difficult but I am learning as well. As I'm getting closer to retiring, my boss wants me to...
  20. Another possible problem is the voltage swing of...

    Another possible problem is the voltage swing of the tach. If it is weak, the motor will run faster because there will be less voltage to drive the amplifiers. I'm not sure what they used for a tach....
  21. Few fuses would blow fast enough to save diodes...

    Few fuses would blow fast enough to save diodes from a hard short.
    Dwight
  22. I'm more of an analog guy. Humor me and make the...

    I'm more of an analog guy. Humor me and make the measurement.
    Also, the high side of the pot adjustment looks wrong. It should be over 5 Volts. I suspect the adjuster is broken inside. The...
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    I was working for a company called speed call (...

    I was working for a company called speed call ( before some reading this were born ) and we made touchtone decoders for taxi cabs ( and cement trucks ). I was probing one board for some failure when...
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    For unused inputs, I typically use 5K( actually...

    For unused inputs, I typically use 5K( actually 4.7K ) or 10K. The reason for using a higher value is that if there is a high load on an output, you don't want the input pin driving the power rail....
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    If I recall correctly, the wire was related to...

    If I recall correctly, the wire was related to blocking the read of the video RAM while the external board video board RAM was attached.
    It sounds like you might need some soldering lessons. You...
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