Sega/Gremlin Astro Blaster

[simplesi]

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

[DanP]

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

[simplesi]

Hi Dan,

I will swap round the boards and see what's what.

No coining and doesn't play blind.
 

[bartie]

I have a manual i think you can use.

http://www.mediafire.com/view/?xmxg9v0405ou1dc

[simplesi]

I have a manual i think you can use.

http://www.mediafire.com/view/?xmxg9v0405ou1dc

Thank you.

[simplesi]

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?

[devpsx]

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

[simplesi]

Many thanks. Will do.

[simplesi]

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.

[Laszo]

Ax = axial = laying down

Rad = radial = standing up

[Etienne MacGyver]

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  

[Laszo]

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.

[devpsx]

Simplesi,

Did you tried

http://www.maplin.co.uk/store-locator/Edinburgh  ?

[simplesi]

Thanks guys. I've bought the capacitors from Maplin.

Will be soldering them now and should have the board tested tomorrow.

[simplesi]

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?