If you want to know what 40 year old RIFA cap looks like, I got you covered. This specimen is from a Kaypro 2 switched mode power supply.
First time in 35 years I’ve used CP/M “pip” to copy a file. Nailed it first time! First refurbished Kaypro floppy drive is working !
I need some 4700pf/300v RIFA caps for Kaypro power supplies, so I ordered replacements from element14.
However, I’m not sure these parts are suitable as they are somewhat smaller than I was expecting. What’s the consensus of the hive mind – can I use them?
UPDATE: consensus was that they are OK to use, provided they fit physically!
Kaypro #1 wouldn’t boot from a Gotek, but Kaypro #2 is up and running!
Update: the problem with Kaypro #1 was the WD9216 data separator. Swapped this chip with one from another system and disk reads started working.
Kaypro #1 lives! Power supply has had RIFA caps replaced, and rejumpered to 240V. Need to clean, lubricate, and test drives before continuing.
I’ve started unpacking the shipment from the US.
2 x Kaypro II, 1 x Kaypro2 , 2 x Kaypro 4, 1 x Kaypro16, and more boxes yet to be opened.
Carefully sliding cable ties under the DRAM sockets and inserting a pad of high density foam results in a firm attachment for the Drastik board.
And the end result – fully assembed and 48k!
This poor System 80 has been subject to cruel and unusual punishment at the hands of previous owners.
I’ve got the Ready prompt (the equivalent of the TRS-80 Memory Size) but it’s been hard work. All of the 2102 video RAMs needed replacing, as well as several LS157 muxes. I managed to link A4 and A5 when replacing a mux – that cost me a few days.
Pressing Enter gives a screen of full graphics blocks – I think the video RAM read is not working fully. But to debug that, I need to understand what is left of a lower case support mod and (I think) software switch for 32 col mode
The battle for the System 80 has begun!
I started with no video, no CPU activity, and a very bodgy looking 64k DRAM upgrade using 4164s
Fixed the CPU issue by replacing a dead electrolytic in the reset circuit. Video came back when I replaced the cable between the boards.
I’ve reversed the 4164 upgrade and am working on the Drastik.
The time honoured “ROM of NOP” is generating square waves on the lower 8 address lines. Now I need to find where they stop being square!
The Model 1 is reporting 48k memory without a DRAM in sight. Only two solder wires required, plus adjustments to the two sets of jumper pads which I have replaced with DIP switches for ease of testing.
I’m still working on the solder-less 16k upgrade. May not be possible. Will look at this tomorrow (maybe).
Two minor issues with the board. Seems I can demux 14 bit DRAM addresses but have forgotten how NOR gates work.
Also had to rewire the keyboard cable as the janky job performed by the previous owner died when I opened the case.
I’ve also 3D printed some replacements for the rubber-ish board standoffs that crumbled to dust when I flattened the boards. If anyone wants the files, let me know.