I've started a thread on another forum regarding a poorly Dragon 32 that I've been given.
I've tried a few things in the hope that I can bring it back to life. All the details and a few pics are posted here....
http://stardot.org.uk/forums/viewtopic. ... 97#p123697
I'm totally unfamiliar with the Dragon 32, but I'm hoping someone with more technical insight into how or what the problem with it might be could offer any advice.
Many Thanks
Mart
Dragon 32 Repair
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Re: Dragon 32 Repair
Hi Mart, welcome to the archive!
By looking at the picture you posted on stardot, and assuming the ram chips are ok, my guess would be that the sam chip is damaged or maybe there's a shorted track somewhere.
Sam chips can be found relatively cheap, so I'd start by replacing it and see what happens.
Best of luck!
By looking at the picture you posted on stardot, and assuming the ram chips are ok, my guess would be that the sam chip is damaged or maybe there's a shorted track somewhere.
Sam chips can be found relatively cheap, so I'd start by replacing it and see what happens.
Best of luck!
Re: Dragon 32 Repair
Just a quick note for the relay test, the command is MOTOR ON (with a space).
Re: Dragon 32 Repair
The space can be omitted it seems to work both with and without.Alastair wrote:Just a quick note for the relay test, the command is MOTOR ON (with a space).
Cheers.
Phill.
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- Location: Mansfield, Notts
Re: Dragon 32 Repair
I've tried both with and without spaces and I don't hear the relay clicking.prime wrote:The space can be omitted it seems to work both with and without.Alastair wrote:Just a quick note for the relay test, the command is MOTOR ON (with a space).
I've gone through some of the tests outlined in the post above and I've drawn a blank with those also. I have noticed however that Pin 20 on the MC6847P is broken off right at the body of the chip and theres no way it can make contact with the socket. Is it supposed to be broken off or lifted?acsi wrote:Turned out to be a faulty 6847P chip.viewtopic.php?f=5&t=1889
I've got the another 7 RAM chips to take off, socket and test but I don't think they've gone bad(Famous last words!!! ) Can anyone suggest a good place to pick up replacement SAM and 6847 IC's?
Mart
Re: Dragon 32 Repair
Pin 20 is DA11, which shouldn't be used in the Dragon as the SAM generates the video addresses.martinjharvey wrote: I've gone through some of the tests outlined in the post above and I've drawn a blank with those also. I have noticed however that Pin 20 on the MC6847P is broken off right at the body of the chip and theres no way it can make contact with the socket. Is it supposed to be broken off or lifted?
It is possible that if one of them is bad it is causing the RAM address lines to become "corrupted" for example if it was pulling it perminently high or low.I've got the another 7 RAM chips to take off, socket and test but I don't think they've gone bad(Famous last words!!! ) Can anyone suggest a good place to pick up replacement SAM and 6847 IC's?
It should also be possible to run the machine with just one bank of 4116s installed though obviously you'll only get 16K or RAM.
Which of the boards do you have, pictures here :
http://archive.worldofdragon.org/index. ... d_Pictures
Cheers.
Phill.
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- Posts: 11
- Joined: Tue Oct 27, 2015 4:55 pm
- Location: Mansfield, Notts
Re: Dragon 32 Repair
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 lineprime wrote:Pin 20 is DA11, which shouldn't be used in the Dragon as the SAM generates the video addresses.
Took the first bank of RAM out and powered on and all the garbage on screen has gone but theres nothing much of anything else happening. No prompt, cursor or anything. Just a solid border with a blank solid orangey centre.prime wrote:It is possible that if one of them is bad it is causing the RAM address lines to become "corrupted" for example if it was pulling it perminently high or low.It should also be possible to run the machine with just one bank of 4116s installed though obviously you'll only get 16K or RAM.
Its a MKII Issue 6 PC10087 with 16x16 RAMprime wrote:Which of the boards do you have, pictures here :http://archive.worldofdragon.org/index. ... d_Pictures
I'll get all the RAM socketed and tested then. I did piggyback a good 4116 on the ones soldered in to see if that showed anything up, but I suppose if more than ones gone kaput then that test would have missed it.
Thanks
Mart
Re: Dragon 32 Repair
Thanks, after all these decades (eek!) I still don't know when you can and cannot omit a space.prime wrote:The space can be omitted it seems to work both with and without.Alastair wrote:Just a quick note for the relay test, the command is MOTOR ON (with a space).
Cheers.
Phill.
Re: Dragon 32 Repair
The way I understand the tokenization and parsing you don't need spaces anywhere.