Dragon's Lair Fans - Arcade Lifestyle
General Chat => Technical Area => Topic started by: simplesi on May 15, 2013, 06:27:15 PM
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Hey. I was lucky enough to pick up a rather glossy looking Sega/Gremlin Astro Blaster.
It's in nice condition, but there seems to be an issue. The machine lights up, monitor powers up, etc. However, there is no sound and what looks like garbled squares on the screen. I assume that the problem is board related. Does anyone have this cab and knows of this problem. Can't find a manual, except for the larger cabs. Does this matter? It contais the G60 cage.
Could it be the boards not getting the appropriate voltage?
Any advice would be appreciated.
Many thanks in advance.
Si
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Most likely a PCB problem, but voltages could be a factor too, easy to test to be sure. Try swapping the main CPU board around into another of the G80 sockets. I take it it doesn't coin and play blind?
Dan
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Hi Dan,
I will swap round the boards and see what's what.
No coining and doesn't play blind.
:)
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I have a manual i think you can use.
http://www.mediafire.com/view/?xmxg9v0405ou1dc
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I have a manual i think you can use.
http://www.mediafire.com/view/?xmxg9v0405ou1dc
Thank you.
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I just checked the voltages as follows:
1. -12v ... -12.07V
2. +12V ... +11.71V
3. AC ... 2.6V
4 GND
5. GND
6. GND
7. -5V ... -5.03V
8. +5V ... +5.01V
9. +5V ... +4.74V
10. +5V ... +4.49V
Are pins 9 and 10 too low?
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Hello simplesi,
I think they are too low.
You could test/change the capacitors c29 / c26.
They are certainly old and don't do their job..
Dev
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Many thanks. Will do.
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Ok, I understand that C26 and C29 are from the EPROM board. I've looked through the manual and found the following:
C29 = 10uf 25V (It says CAPE... what is that?)
C26 = 0.1uf 16V AX (CAP CER = Ceramic?, what is AX?)
Sorry for the silly questions... when I visit Farnell there are literally 1000s of capacitors and I'm not sure which to get. Aluminium, Lead, Ceramic, etc.
Thanks in advance.
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Ax = axial = laying down
Rad = radial = standing up
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Ok, I understand that C26 and C29 are from the EPROM board. I've looked through the manual and found the following:
C29 = 10uf 25V (It says CAPE... what is that?)
C26 = 0.1uf 16V AX (CAP CER = Ceramic?, what is AX?)
Sorry for the silly questions... when I visit Farnell there are literally 1000s of capacitors and I'm not sure which to get. Aluminium, Lead, Ceramic, etc.
Thanks in advance.
and in addition to Laszo, "CAPE" i think its CAP-Electrolytic ;)
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Ok, I understand that C26 and C29 are from the EPROM board. I've looked through the manual and found the following:
C29 = 10uf 25V (It says CAPE... what is that?)
C26 = 0.1uf 16V AX (CAP CER = Ceramic?, what is AX?)
Sorry for the silly questions... when I visit Farnell there are literally 1000s of capacitors and I'm not sure which to get. Aluminium, Lead, Ceramic, etc.
Thanks in advance.
These caps are very common, don't you have a local electronics shop, these caps cost less then a euro together. C29 will probably not be available in 25v, but everything higher will do.... 63 volt should be widely available.
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Simplesi,
Did you tried
http://www.maplin.co.uk/store-locator/Edinburgh ?
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Thanks guys. I've bought the capacitors from Maplin.
Will be soldering them now and should have the board tested tomorrow.
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Morning. Both C29 and C26 were replaced and I've just tested the boards. Unfortunately, things haven't worked out and I am still seeing the same problem on screen.
Do you think this could now potentially be a microchip problem?
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I dont know if you have a eeprom reader / writer ?
If you do , you can verify the content of the roms and see if they are right.
did you reseat and cleaned the legs of the chips already ?
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Hi Etienne,
How are you? All good I hope.
I don't have an eeprom reader/writer. I will reseat the chips. How best would you clean the legs?
Thanks,
Si
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Hey, long time no PM ;)
I am fine
By the way, i looked through the manual and page 15 & 16 describes a selftest.
did you executed that procedure yet ?
As for the legs of the chips, it usually is working when you just reseat them, the "scraping" from reseating many times cleans the legs and make contact again.
if not, try some alcohol on a qtip but becarefull not to break off the legs!
if its really corroded, you can use very fine sandpaper and sand the legs.
After that you also need to check if the sockets are corroded, and maybe replace them.
whatever you decide to do, it never hurts to check continuity by putting one probe from your multimeter on the leg of the chip and the other on a trace on the board and check continuity.
although that is some work, you are sure that the legs make contact with the corresponding points on the board
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Hi Etienne,
Just reseated the eeproms... a little graphic difference, but nothing major. The voltages across 9 and 10 are still the around 4.48 and 4.64V
Also, I noticed that the schematics show that the bottom row of eeproms should have only one chip in them (to the far right). On my board I also have 3 to the left 904-6. Is this normal?
I will check continuity as well.
Thanks.
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I dont know about how many eeproms on which board, but i know that +- 4,5 volt is too low
you need 5 volts there, sou it could be that that is your problem, or maybe you got a bad rom or something
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Yep that's way too low.
How's the condition of your edge connector ? if you can slide it on and off easily it's gone too far and replacement is required....
Here's my little video showing the difference between a worn out and a new edge connector: http://www.youtube.com/watch?v=FV1Bb5s8pRU&list=UUn47kbEAlRBSmWmdae45P2w&index=57
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Here's my little video showing the difference between a worn out and a new edge connector: http://www.youtube.com/watch?v=FV1Bb5s8pRU&list=UUn47kbEAlRBSmWmdae45P2w&index=57
I have exactly the same edge connector problem with one of my SWs. :-*
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I have 5 boards in the G80. Some are loose like you mention. The problem I see is that all 5 boards connect to a masterboard. I'll need to replace these connectors. I can swap boards around. I think there are 7 or 8 slots. Maybe I can rearrange the boards and see if that makes any difference? The boards do not have an order.
Thanks again for your advice.