Author Topic: Sega/Gremlin Astro Blaster  (Read 12017 times)

Etienne MacGyver

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Re: Sega/Gremlin Astro Blaster
« Reply #15 on: June 03, 2013, 01:03:37 PM »
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 ?

simplesi

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Re: Sega/Gremlin Astro Blaster
« Reply #16 on: June 03, 2013, 01:10:04 PM »
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

Etienne MacGyver

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Re: Sega/Gremlin Astro Blaster
« Reply #17 on: June 03, 2013, 01:15:00 PM »
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
« Last Edit: June 03, 2013, 01:21:44 PM by Etienne MacGyver »

simplesi

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Re: Sega/Gremlin Astro Blaster
« Reply #18 on: June 03, 2013, 02:01:28 PM »
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.

Etienne MacGyver

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Re: Sega/Gremlin Astro Blaster
« Reply #19 on: June 03, 2013, 02:32:14 PM »
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

level42

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Re: Sega/Gremlin Astro Blaster
« Reply #20 on: June 03, 2013, 05:33:49 PM »
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

Belike

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Re: Sega/Gremlin Astro Blaster
« Reply #21 on: June 03, 2013, 05:52:21 PM »

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. :-*

simplesi

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Re: Sega/Gremlin Astro Blaster
« Reply #22 on: June 04, 2013, 09:19:42 AM »
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.