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Thread: replacement Lamp?

  1. #1
    Join Date
    Oct 2007
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    Default replacement Lamp?

    While working on the 16B , the "power on" red panel lamp bulb on the front has decided to call it a day, Can anyone point me to a supplier of these small bulbs,these are the same lamp bulbs as used in the 5, 12, 15, meg , trs 80 external HD units, used in the red, and green, square indicator lights, There are no markings on these bulbs,( just too small I quess) I have looked at digi- key, and tried to look at radio shack spare parts list for various hard ware, they do give there own part no. but no details? any help would be great. Thanks,

    Harry

  2. #2

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    I don't know the answer yet, but here are some pictures for reference. The DIP is for scale, as I don't have any bananas handy.

    IMG_3479.jpg IMG_3480.jpg IMG_3478.jpg

  3. #3
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    Hi NF6X

    Hey thanks for putting pics up, pictures sometimes better than words! Hopefully these are still available somewhere?

  4. #4
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    I don't know either, but Roy T. Beck suggests,

    "Connect a 470 ohm, 1/2 watt resistor across the red lamp socket on the front of each drive. The purpose of this is to allow the write protect to function regardless of the lamp. Without this, you may suddenly discover your hard drive has become write protected for no obvious reason; the real reason being either a burned-out lamp or one which makes poor connection in its socket."

    https://archive.org/details/TRS-80_H..._Repair_19xx_-

    Mike

  5. #5

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    Quote Originally Posted by MikeModifed View Post
    I don't know either, but Roy T. Beck suggests,

    "Connect a 470 ohm, 1/2 watt resistor across the red lamp socket on the front of each drive. The purpose of this is to allow the write protect to function regardless of the lamp. Without this, you may suddenly discover your hard drive has become write protected for no obvious reason; the real reason being either a burned-out lamp or one which makes poor connection in its socket."

    https://archive.org/details/TRS-80_H..._Repair_19xx_-

    Mike
    Yes, the Tandy cheapos using the lamp filament as part of the write-protect circuit.

    I would like to find a source for these lamps as well.

  6. #6

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    It's been a while since I was inside my Apple IIe, but I seem to recall that the burned out power indicator lamp in mine is of a similar style. It's also a two-pin lamp, but I don't recall whether it has the plastic base insulator like the one in the TRS-80 machines. I don't have time to open it up at this instant, but maybe this will give somebody a hint that leads in the right direction?

    I had considered seeing if I could make a substitute (in the IIe) using an LED and a very small leaded resistor, but I haven't tried it yet.

  7. #7

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    I'm reminded that I have some military CUCV trucks, based on 1980s Chevy Blazers, whose charging systems don't work if the alternator warning lamps burn out.

  8. #8
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    Default

    Looks a lot like a T-1 3/4 7381 bi-pin lamp. Shouldn't be hard to locate--6.3V


  9. #9
    Join Date
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    Maybe one of the Chicago Miniature (VCC) Bi-Pin lamps would be an appropriate replacement?

    http://www.mouser.com/catalog/catalogusd/648/152.pdf

    Measure the lead spacing, lamp diameter, and operating voltage and current and see if there is anything that matches close enough.

  10. #10
    Join Date
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    Quote Originally Posted by Chuck(G) View Post
    Looks a lot like a T-1 3/4 7381 bi-pin lamp. Shouldn't be hard to locate--6.3V

    Hi Chuck, I have been looking at the T-1 lamps, and they are very close, the two wire pins on the originals are aprox 9.5mm long ( 3/8"), where as the T-1 range all seem about 6.3mm long( 1/4"), maybe snipping them off, and soldering longer pins will have to do, or maybe the 6.3mm pins might just reach, a case of checking the depth of the contacts in the holder I quess.

    gslick... Thanks for link, some of those listed do look promising, and have long pins,

    thanks

    Harry

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