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Is the keyboard interface your own design or do you have more info on it? I'd like to be able to take all the credit, but the keyboard interface is sort of mix and match of bits and pieces from here and there :) I'm also intrigued to know more about the keyboard interface - a regular question on th...

As this is as good a place as any I suppose, I thought I'd share some pictures of my Dragon32. I don't normally give up easily but I've totally given up on trying to repair this. Its not all bad though cos my poorly Dragon32 has now been given a new lease of life and been reborn as the.................

I think that replacing the roms is such a cheap option that may be worth the try OK Rob you talked me into it :lol: Having spent £30+ on replacement parts though I'm at the point where I've got to be sensible and cut my losses :( If its a cheap option then I'll give it a try before giving up comple...

Thought I'd pop by and offer an update and a bit of closure to this post, for my sake more than anything :lol: I got to the bottom of the missing -5v. Because it looked dubious, I redid the solder joints on the only RAM socket installed from a previous owners repairs. The new solder had unfortunatel...

Ive swapped out the 7905 reg this evening and as expected it made no difference to the -5v. But at least I can rule that out :) As pretty much most of the main chips on my motherboard are now socketed I removed them all and then tested the voltage at the RAM sockets and surprise, surprise, the -5v i...

The culprit was the capacitor C5 on the power board, the one between the R5 resistor which gets pretty warm and the row of power diodes. Make sure you get the polarity right if you replace this capacitor! I'm willing to give any suggestion a try so I've ordered some replacements for C5. The screen ...

I would suggest disconnecting the power board from the main board and check if the -5V is OK unloaded. Then see if it can maintain -5V into a 100 Ohm resistor. The -5v is there when the power board is disconnected and is still good through a 100 Ohm resistor. Resist the temptation to fix the -5V re...

I've now socketed all the remaining 4116 ram IC's and in doing that and testing them I did manage to turn up 1 possibly 2 bad ones! Now when I've re-inserted known good chips ( tested them in the lower 16k of a spare speccy 48k ) I'm getting a black and white display, with the same garbage appearing...

Pin 20 is DA11, which shouldn't be used in the Dragon as the SAM generates the video addresses. As I've not worked on a Dragon before, I wasn't sure if the missing pin was down to someone else handywork somewhere along the line :) It is possible that if one of them is bad it is causing the RAM addr...

Just a quick note for the relay test, the command is MOTOR ON (with a space). The space can be omitted it seems to work both with and without. I've tried both with and without spaces and I don't hear the relay clicking. :( Turned out to be a faulty 6847P chip.http://archive.worldofdragon.org/phpBB3...