[Techtoolslist] RASTER: FW: Using 8080 pod on Midway 8080 boards (Space Invaders)

[John Robertson]

David Shoemaker wrote:

> Any chance I could have you open one up and look at the ground lead on the

> twisted pin cable?  I have an 8085 pod I tried to borrow the twisted pair

> cable from and it has the shield ground tied to pin 20.  That doesn't work

> on the 8080 as that pin is +5.  Ground should be tied to pin 2.  I am

> wondering how they did that I suspect it is in the potted UUT end as I don't

> see anything on the connector end.

>

> David

>

>   


Hi David,

I've taken these pods apart enough times to tell you this off the top of 
my head. The twisted pair cable is broken out for one row alternately 
inside the pod case, one wire goes to a common metal strip, the other to 
the pin header. The strips are tied together and have a short jumper 
wire that simply goes to the screw on the left end of the connector.

At the encapsulated end all the grey ground wires appear to be tied 
together as well as to any ground pins on the plug.

So you can't exchange shielded cables between different pods UNLESS they 
have the same ground connections on the CPU.

John :-#)#

>

> -----Original Message-----

> From: owner-rasterlist at vectorlist.org

> [mailto:owner-rasterlist at vectorlist.org] On Behalf Of Alex Yeckley

> Sent: Wednesday, February 20, 2013 4:15 AM

> To: 'David Shoemaker'; 'Technical Tools Mail List'; jrr at flippers.com;

> rasterlist at vectorlist.org

> Subject: RE: [Techtoolslist] RASTER: FW: Using 8080 pod on Midway 8080

> boards (Space Invaders)

>

>   

>> Do your pods have the twisted cable or the straight?  Both mine have 

>> the straight.

>>     

>

> Our 8080 pods have the OEM twisted cables.  Our 6502 pods (re: Clay's

> Tempest question) come in both twisted and the flat cables.  I'm assuming

> the flat cable is a non-factory replacement item, but could be totally wrong

> about that.  The 6502 pod that failed just happened to have had a flat cable

> but I'm confident the drive problem was unrelated; we found one specific

> driver output that wasn't going sufficiently high once plugged into a "real"

> target board.  It wasn't a general malaise of the address lines like you

> might expect from transmission line losses or higher EMI susceptibility due

> to the flat cable if that's what you are wondering.

>

>   

>> Are you using a 9010 or a 9100 to drive the pod?

>>     

>

> Both...

>

> Alex

> ----

> ayeckley at elektronforge.com

> www.elektronforge.com 

>

>

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>

>

>   



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