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Dragon Spirit

RandomRetro

RandomRetro

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So admittedly I am newer to the pcb repair scene. All suggestions and guidance welcome.

My new Dragon Spirit PCB is causing me heartburn.

Initial boot:
1DE1CB71-EDD3-4687-B1B4-3223B7FC6A06.jpeg

Switch DIP1 to test:
FC9DF618-C6C5-48AF-80EE-387822035428.jpeg

Switch DIP1 back off:
F522C76F-A01B-4EC3-965A-EF24E2C9F1C4.jpeg

Issues:
A) when board boots there is no audio.
B) honestly not sure what chip is RAM6
C) manual is worthless
D) super confused why the board boots after that above steps/sequence

Next steps:
1) Find RAM6
2) check voltage on audio chips and circuit
 
It's probably upset that it's sideways. If you make it vertical it may behave better.


RandomRetro said:
C) manual is worthless
Click to expand...
But really: the manual tells which RAM to check given a RAM 6 error, so it can't be that useless. :P

Per the manual: "RAM at location B2, D2, or E2 on the CPU PCB"

Also per the manual: "CPU PCB is the smaller circuit board"

Start by testing those guys, and replace what isn't working properly. Easier to focus on one issue at a time, and who knows, maybe it'll solve the other issue too.

EDIT: Further reading of the manual confirms the issue is with D2. Try piggybacking a known good RAM, or just replace it and see where you're at.
 
Man crow tastes so good... thanks @rewrite for not just responding RTFM. I totally missed it and it was right there.
3E253A2F-F26D-4F4E-AD58-472813518FB5.jpeg

Now I need to order one of those bad boys up and try the piggyback and swap.

Funny enough The current chip in D2 states clearly in sharpie that it is ok... why does it have to lie like that!
8D64FC35-7F35-46CF-BC45-88A2321D44D6.jpeg
 
RandomRetro said:
Funny enough The current chip in D2 states clearly in sharpie that it is ok... why does it have to lie like that!
Click to expand...
lol, that's great.

Those are socketed, so no sense piggybacking, just swap 'er on out.

For fun, you can try swapping it with E2 or B2 and see if the error follows the chip.
 
rewrite said:
For fun, you can try swapping it with E2 or B2 and see if the error follows the chip.
Click to expand...
Ok, so I am glad I tried that...

Cleaned the legs on the chips and swapped D2 and B2 (E2 is a different type chip). Things booted up cleanly without having to do the test mode DIP switch dance. But when I went into test mode I got a ROM4 error. Based on the manual; see @rewrite I am already learning that reading is not overrated, that is an issue with N10. N10 is on the program board and an EPROM which looks original and consistent (both chip look and label) with the other ROM chips on the board.

Swap D2 and B2 back to original sockets, and I get a clean boot, but test mode shows RAM6 Error again with an different 4-digit number '080C'. This still points to an issue with D2.

So I think I am going to order a new RAM chip for D2 (TMM2064P-70), and a ROM chip for N10 (MBM27C512-25). Maybe I could just erase and reprogram N10, but likely best to have a backup/replacement on hand regardless.

I could send the board back to the original owner, but I fear that may just risk more damage and I think this is more than fixable with a couple chips and a little time. Agree/disagree?
 
RandomRetro said:
Swap D2 and B2 back to original sockets, and I get a clean boot, but test mode shows RAM6 Error again with an different 4-digit number '080C'. This still points to an issue with D2.

So I think I am going to order a new RAM chip for D2 (TMM2064P-70), and a ROM chip for N10 (MBM27C512-25). Maybe I could just erase and reprogram N10, but likely best to have a backup/replacement on hand regardless.
Click to expand...
So we know D2 is definitely bad. It's possible N10 is fine, but with B2 being bad (because you swapped in the bad D2) you're getting a false error. But I suppose it's also possible it's bad.

27c512 is a super common eprom, you should have no trouble finding one. If you don't have a programmer, send it my way and I'll get it out to you pre-programmed.
RandomRetro said:
I could send the board back to the original owner, but I fear that may just risk more damage and I think this is more than fixable with a couple chips and a little time. Agree/disagree?
Click to expand...
Rule of thumb usually is to contact the seller and ask them how comfortable they are letting you work on the board before messing around with it.

In this case though, they're socketed chips, and I can't see how you'd cause any damage.

I would, at a minimum, reach out to them, tell them the issues, and let them know you're going to order a new RAM chip and an eprom to see if you can get it up and running again for a few bucks.
 
rewrite said:
27c512 is a super common eprom, you should have no trouble finding one. If you don't have a programmer, send it my way and I'll get it out to you pre-programmed.
Click to expand...
Thanks I will let you know. Yeah, I sent a note to previous owner, but I suspect they will say have at it. Will follow up later...
 
First replacement chips apparently got lost in the mail, but finally have more on their way. Itching to get back to fixing this board. But first package I have lost in the COIVD era so I guess not the worst thing.
 
Replacement RAM chips arrived. Swapped D2 and B2, but now I just get a black screen. Time to investigate further...
 
i have a cpu board, it works perfectly. If you are interested, send me a message.
 
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