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  1. S

    Kaypro 4: Boschert XL53-3601R PSU: Trying to find replacement switching transistor (Q1)

    That's actually a generic Boschert PSU from 1979 and doesn't actually match the XL53 from 1983. I've looked into this previously.
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    Kaypro 4: Boschert XL53-3601R PSU: Trying to find replacement switching transistor (Q1)

    Well, I guessed that it was a 2N2222A as that generally fits the frequency range and probable voltages but that changed nothing. I'm guessing that something else has died. I think that I'm going to have to fit a modern supply, such as the Mean Well RT-85B.
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    Kaypro 4: Boschert XL53-3601R PSU: Trying to find replacement switching transistor (Q1)

    When the main RIFA delayed smoke generator popped on the Kaypro 4 power supply (Boschert XL53-3601R) it took out the switching transistor, Q1, so I need to replace it. However, the only part of the transistor can with any corrosion is the part with the type number. All I can read are the final...
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    Apricot PC finished at last

    Have a look here: http://actapricot.org/support/
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    Apricot FP/Portable

    I've got the "mouse" working. The Portable needs a later version of the driver than that for the other F Series. The disk images I shared above have that driver installed. (You can write the images to real floppies using RawWrite on PCs or dd on Linux/macOS. They are standard 720K.) With...
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    Apricot, Research Machines, etc., British computers in general

    I've an A4000. I think that of all the Acorn ARM machines it must be the most limited in terms of expandability. It can only take a mini-podule, it can't have a second floppy drive, it maxes out at 4MB of RAM and the ARM250 isn't quick and can't be upgraded and the IDE interface is so dumbed...
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    Apricot, Research Machines, etc., British computers in general

    I've currently been fixing a "barn find" F1, an F2 which got sent to me bouncing around in a box with no padding via Parcel Farce and a recently acquired FP (Portable). Amazingly, after cleaning off the rotted leaf litter (and changing out the RIFA smoke generators in the power supply) the F1...
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    Apricot Fi Mono Monitor

    The F Series Monitor is not pin compatible with the Portable. The F Series DB9 socket is wired very differently and has a 17V DC power pin which powers the monitor. The power for this doesn't come from the main PSU, instead it uses an external 17V AC supply plugged into the back of the...
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    Sun 3/80: Bad "decode1" chip: Need system schematics or at least pinout.

    I've a Sun 3/80 which whilst in storage developed a fault in the decode1 chip meaning that it can't output the /RD signal to the serial SCC. Given that this is required at an early stage in the boot the machine just flashes the LED briefly and sits there polling writing to the status register...
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