Very interesting, thanks for the video. I just bought one of these with the exact issue you mentioned, but it has all the original manuals, documentation, and software so I went for it. I think I've found a shorted capacitor on the motherboard.
That is good, hopefully an easy fix! There are a multiple capacitors on the same same voltage rails, so you may have to de-solder all of them to determine which one has failed. Also confirm the issue is isolated to the mainboard first by removing the accessory cards and testing again.
@@ANTandTEC Yes, I'll be giving all that a go, though I feel a bit out of my depth being a programmer not an electrical engineer. I do believe it's the motherboard as the issue persisted when every other component was unplugged from the power supply. Please could you let me know if you know any more detail about the file card? I heard plus 3.5" 10MB file card but I'm having a tough time searching for it. I'd love to find one for my computer to get some storage. Do you think you'll do more vintage computing content? Big appetite for it on youtube these days! Thanks again
@Ed unplug the power supply and measure resistance on the main board between ground and each voltage rail. If one is short then unsolder every tantalum cap on that rail, one will most likely be shorted. The unit will operate without the hard drive. It originally was sold with 2 x floppies or 1 floppy and one hard drive in the front bays. Any 8 bit ISA controller and hard drive should work with the Compaq. Either all in one card or separate controller card and a full or half height hard drive in one of the bays. I do have a video I need to make with a Commodore PET repair.
-5v is present on the ISA bus. If the cards in the machine are not using that pin then you can probably run it without. You can always derive a -5v rail from the -12v using a 7905 regulator if required.
@@ANTandTEC Thanks for getting back to me. That is very helpful, as there are a number of things about this computer that are quite difficult to get information about online.
@@jtype2426 No problem. If the ISA cards do use -5v it will be very low current, and a 7905 will be more than capable. Or you could try and source an old AT power supply like I did that will already have -5v.
@@ANTandTEC What I had in mind was to use a modern motherboard and power supply but maintain the ability to run ISA devices in order to operate the ISA display adaptor (rather than to adapt signal from a VGA or HDMI device). This would mean being able to retain the CRT, the floppy drives, but replacing the internals of the keyboard and the the mobo. The more modern PSU would certainly help in that ambition. I am still trying to understand how feasible this is. I am a little torn. The machine is lovely as it is, but little more than an ornament. Turning it into a usable (and incredibly stylish!) home server seems a much more useful and dignified way for it to be put to use.
@@jtype2426 If the mobo you are putting in it has ISA slots (which it will need to have if you want to keep the existing cards), then you will already have -5v, either from the PSU or the mobo might derive it itself.
20 megabytes was a lot back then haha, how far weve come.
Cross your fingers i get one soon!!
New channel with great english, nice
Glad you liked it 🙂
Very interesting, thanks for the video. I just bought one of these with the exact issue you mentioned, but it has all the original manuals, documentation, and software so I went for it. I think I've found a shorted capacitor on the motherboard.
That is good, hopefully an easy fix! There are a multiple capacitors on the same same voltage rails, so you may have to de-solder all of them to determine which one has failed. Also confirm the issue is isolated to the mainboard first by removing the accessory cards and testing again.
@@ANTandTEC
Yes, I'll be giving all that a go, though I feel a bit out of my depth being a programmer not an electrical engineer. I do believe it's the motherboard as the issue persisted when every other component was unplugged from the power supply.
Please could you let me know if you know any more detail about the file card? I heard plus 3.5" 10MB file card but I'm having a tough time searching for it. I'd love to find one for my computer to get some storage.
Do you think you'll do more vintage computing content? Big appetite for it on youtube these days!
Thanks again
@Ed unplug the power supply and measure resistance on the main board between ground and each voltage rail. If one is short then unsolder every tantalum cap on that rail, one will most likely be shorted.
The unit will operate without the hard drive. It originally was sold with 2 x floppies or 1 floppy and one hard drive in the front bays. Any 8 bit ISA controller and hard drive should work with the Compaq. Either all in one card or separate controller card and a full or half height hard drive in one of the bays.
I do have a video I need to make with a Commodore PET repair.
Would you know what the -5v rail runs to inside the system? I was hoping to replace mine with an modern ATX type supply.
-5v is present on the ISA bus. If the cards in the machine are not using that pin then you can probably run it without.
You can always derive a -5v rail from the -12v using a 7905 regulator if required.
@@ANTandTEC Thanks for getting back to me. That is very helpful, as there are a number of things about this computer that are quite difficult to get information about online.
@@jtype2426 No problem. If the ISA cards do use -5v it will be very low current, and a 7905 will be more than capable.
Or you could try and source an old AT power supply like I did that will already have -5v.
@@ANTandTEC What I had in mind was to use a modern motherboard and power supply but maintain the ability to run ISA devices in order to operate the ISA display adaptor (rather than to adapt signal from a VGA or HDMI device). This would mean being able to retain the CRT, the floppy drives, but replacing the internals of the keyboard and the the mobo. The more modern PSU would certainly help in that ambition. I am still trying to understand how feasible this is. I am a little torn. The machine is lovely as it is, but little more than an ornament. Turning it into a usable (and incredibly stylish!) home server seems a much more useful and dignified way for it to be put to use.
@@jtype2426 If the mobo you are putting in it has ISA slots (which it will need to have if you want to keep the existing cards), then you will already have -5v, either from the PSU or the mobo might derive it itself.
Where did you find this
Got it from the US. There are usually several for sale there. This one is on eBay at the moment.