Fix Double Dragon pcbs

abobo

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Jan 9, 2010
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Arezzo, italy, Italy
Hi all, i have 3 original double dragon pcbs,
all workings but with graphic problems (and sometimes audio problems),
how can identiify video chip?
how can identify ram video?

i tried to swab all ics (eprmos) form different boards,
and i'm sure that it's not an eprom problem

regards

francesco
 
Need more information.

What kind of audio problem? Have you shotgunned the caps in the audio section yet?

On the graphics problems, have you looked at each board for physical damage on both sides? If it's not a gouged trace or smashed component then I'd look at the SRAM chips on the video board. Don't forget about corrosion damage! Any liquid spills, crusty areas, or spots that look like rodent urine?

If it looks like the image is all out of whack timing wise then look at the 2 42 pin chips on the CPU board. <--- EDIT: Scratch that. I'm getting this and another board mixed up. There aren't any 42 pin timing chips on this board.

RJ
 
Last edited:
no corrions, how can identify ram chips?
are they soldered?
cpu is fine...
the problem is on video ram or video chip
 
There is no "video chip" on this board. It's all discreet components.

Look at the 24 and 28 pin chips on the video board that aren't EPROMs and run their chip numbers through http://www.datasheetarchive.com to see if they are SRAM chips. You can download the data sheets on them from there too.

RJ
 
I have 2 that I've fixed... One going back to the person who sent it in for repair and one that I'm about to sell.

They were troublesome to fix, but I did learn quite a bit while troubleshooting them.
 
It would help if you would put location information in your profile.

I know of folks that do some repairs in Italy and in the UK that are on other forums.
 
ok good, i live in italy at Arezzo in tuscany,
do you know any italians that repairs pcbs?


thanks

francesco
 
dragon

First of all check the ground or 5 volts jumper(i forget which it is) that goes from one side of the board to the other connecting all the ground or 5 volt lines. They get cold soder and crack joints. that usually solves most problems.
 
i have 3 boards with 3 different graphic problems...

http://www.mondoarcade.it/download/d1.jpg

http://www.mondoarcade.it/download/d2.jpg

http://www.mondoarcade.it/download/d3.jpg

http://www.mondoarcade.it/download/d4.jpg

i found ram chips they are on the bottom board marked as toshiba tmm2018d-45,
do i have to change it? where can i find it?

Just fixed my DD board which had the same fault as yours in picture D2.JPG. Problem was the 74LS273 chip IC53, it had a lot of dead pins.
 
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