exxos's Atari, Amiga & retro forum

Well, I got given a couple of Kaypro 4 machines, but only one keyboard and no keyboard cables.


As an experiment I turned on the machine which I had been told had been tested... Bang! Flash! Crackle! The smoke generator was activated! :-)

Oh well. I won't have space in the car this visit to take them back to Cornwall. They'll have to await the next trip.

stephen_usher wrote: 31 Jan 2024 20:30 Well, I got given a couple of Kaypro 4 machines, but only one keyboard and no keyboard cables.


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As an experiment I turned on the machine which I had been told had been tested... Bang! Flash! Crackle! The smoke generator was activated! :-)

Oh well. I won't have space in the car this visit to take them back to Cornwall. They'll have to await the next trip.

That is so awesome!! Kaypro's I mean, not the smoke generators :)

Nice, always wondered about those old Kaypros and what they were capable of.

These two had been kept in an out building. One without a keyboard is obvious by how much dirt is on the screen.

My friends have four more Kaypros in better condition acting as a printer stand in their living room but don't want to get rid of them.

PhilC wrote: 31 Jan 2024 20:46 Nice, always wondered about those old Kaypros and what they were capable of.

They're merely bog standard CP/M machines. Twin 360K floppies, 64K RAM, generally 2.5MHz Z80 (The X variants are 4MHz) with a green screen CRT. ADM3A display emulation.

Looked inside the other Kaypro now. This one has an Aztec PSU. Both smoke generators are intact.

It turns out that the difference between the Kaypro 2 and the Kaypro 4 is merely the type of floppy drives installed. The 2 has single sided drives and the 4 double sided. Otherwise they're identical.

stephen_usher wrote: 31 Jan 2024 20:50

PhilC wrote: 31 Jan 2024 20:46 Nice, always wondered about those old Kaypros and what they were capable of.

They're merely bog standard CP/M machines. Twin 360K floppies, 64K RAM, generally 2.5MHz Z80 (The X variants are 4MHz) with a green screen CRT. ADM3A display emulation.

Ah right ok, another CP/M machine then. makes sense.

Got back to Oxford yesterday evening.

Having brought one of the Keypros home, the one with the explodified RIFA, I had another look.

I replaced the exploded and the other three RIFAs and gave the PSU a test... nothing. Looks like the exploding RIFA took something else out. It's not the fuses as I'm getting 120V on one of the heatsinks so there's power. I wonder if it's the low voltage switching transistor as that's the most vulnerable to spikes, though it's supposed to be protected by a zener diode.

stephen_usher wrote: 03 Feb 2024 09:04 Got back to Oxford yesterday evening.

Having brought one of the Keypros home, the one with the explodified RIFA, I had another look.

I replaced the exploded and the other three RIFAs and gave the PSU a test... nothing. Looks like the exploding RIFA took something else out. It's not the fuses as I'm getting 120V on one of the heatsinks so there's power. I wonder if it's the low voltage switching transistor as that's the most vulnerable to spikes, though it's supposed to be protected by a zener diode.

Could the Zener have died? Is it possible to run it off bench PSUs for testing or does it have too wide a variety of voltages?

I'm slightly fascinated by these old CP/M portables I must admit.

It needs the PSU's 12V to power the display. I could potentially lash up a luminance+sync->composite sync cable but far better to get the PSU working.

It's quite possible that it's the Zener. I'll have to see.

I've had to go into work this morning as the virtual infrastructure lost connectivity to the new storage, on which all the VMs reside. The two Dell 10Gb switches had both reverted to an older set of settings for some reason and lost the new VLAN configuration I set six months ago and definitely saved.