Re: Stuck output(s) on G80 X/Y Cards / CPU no LED.

When I worked on G80 stuff, I used a backplane board from
a spare cage. I would place the 'test' board all the way
to the right for easy access via scope or logic probe.

Too bad somebody didn't make an extender card like they
used on the S-100 systems.

Todd

----- Original Message -----
From: "Chris Brooks" <armis@pcdochouston.com>
To: vectorlist@vectorlist.org
Sent: Tuesday, January 17, 2012 3:14:32 PM GMT -06:00 Central America
Subject: RE: VECTOR: Stuck output(s) on G80 X/Y Cards / CPU no LED.

CPU will take clocking from the XY boards IF the crystal oscillator on the XY boards is functioning AND plugged into the card cage – that’s really all there is to the clocking circuit to the CPU in G80 systems.

I find it most helpful to solder-tack a set of test leads to various points on a board that are then terminated to a barrier strip, and then insert the board into the cage.  You can then scope/test them as needed.

Thanks,

Chris Brooks

713-341-9850

From: owner-vectorlist@vectorlist.org [mailto:owner-vectorlist@vectorlist.org] On Behalf Of Arcadius Stempak
Sent: Tuesday, January 17, 2012 8:47 AM
To: vectorlist@vectorlist.org
Subject: Re: VECTOR: Stuck output(s) on G80 X/Y Cards / CPU no LED.

Anyone have any ' good ' methods for troubleshooting SEGA G80 CPU

and / or - X/Y Timing / Control - Cards?

I also wonder if I may have a Watchdog issue on the CPU Board itself?

But if the X/Y Cards provide clocking to the CPU Board and if these are

not functioning correctly, then I suspect the CPU may never come up.

Again appreciate any ideas that anyone can offer.

Thanks,

Sent: Tuesday, January 10, 2012 9:59 PM
Subject: VECTOR: Stuck output(s) on G80 X/Y Cards / CPU no LED.

>I have three sets of Sega G80 X/Y Timing and Control Cards. 

>All three sets of the ' Timing ' Cards remain stuck a constant voltage 

>output in the range of 1.50 to 1.66 VDC. Also the ' Control ' Card output 

>remains at 0.16 to 0.22 VDC on all three ' R G B ' ouputs. I suspect that 

>this may be the reason that my CPU card will not come up, and the CPU's

>LED remains off. I have replaced the crystal, on the CPU card, Z80 CPU

>along with memory (2114) on both the X/Y and CPU Cards. I also replaced

>the LED, itself. So far I get no output and the CPU seems to be non functional.

>As a sidenote, I am using an Original Sega G80 power supply / transformer.

>All voltages(including the Reset power on voltage) measure as ' Good ' .

>Appreciate any ideas that anyone can offer.

>Thanks,

 
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Received on Tue Jan 17 19:24:42 2012