Re: Gravitar Weird Start up / hi score save

Hmmm, well then. Im guessing the only other problems might be related to
the EAROM being bad (I think they do have a limited lifespan).

You can buy them for $8 at...
http://www.mikesarcade.com/cgi-bin/store.pl?sku=ER2055

Datasheet is at... http://www.jrok.com/datasheet/ER2055_EAROM.pdf

Bob Langelius wrote:

> Jess,
> I checked the voltages and the -28V measures -27.95V at the test point
> and at the leg of the chip. It seems steady with a DMM. Do you think
> the caps could still be problematic? Btw 5V is running at 5.05V.
>
> I also noticed that on the weird graphic issue. cycling the power to
> the cab fixes it., but jumping the reset test points doesn't. it will
> come back up with the disjointed vectors and klingon text.
>
> Thanks,
> Bob
>
> ------------------------------------------------------------------------
> *From:* owner-vectorlist@vectorlist.org
> [mailto:owner-vectorlist@vectorlist.org] *On Behalf Of *Jess Askey
> *Sent:* Tuesday, September 20, 2005 7:35 PM
> *To:* vectorlist@vectorlist.org
> *Subject:* Re: VECTOR: Gravitar Weird Start up / hi score save
>
>
> The EAROM uses a capacitor doubler circuit to produce something like
> -28V for the EAROM. It runs off the -15V supply I belive. Im doing
> this from memory so it may be +28V running off the +15V supply.
>
> anyway, when the doubler caps dry out, the supply drops back down to
> +/-15V and the EAROM won't work that way. There a diode as a part of
> the doubler but I have never seen that go bad, just the electrolytics.
> Try replacing both of those and I bet you will be good to go.
>
> I guess first measure your voltage to see if it is low tho. :-)
>
> good luck
>
> Bob Langelius wrote:
>
>> I just got Gravitar running in my Space Duel cab. At cold start it
>> has weird letters and vectors. A power cycle fixes it.
>>
>> Also the Hi scores don't save after a power-down. I changed Earom -
>> same situation. How does the earom work? Do they fail from age or use?
>>
>> Self test shows no failures.
>>
>> Thanks,
>> Bob
>
>

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Received on Thu Sep 22 10:13:22 2005