8800c Mainboard problem

Discuss construction, troubleshooting, and operation of the Altair 8800c computer

8800c Mainboard problem

Postby toml_12953 » February 9th, 2019, 12:25 pm

I have the 9-slot mainboard suggested in the Altair 8800c docs. I've finally gotten enough time to try to finish it. I wired up the power supplies (also the ones suggested) and when I flip the Front Panel switch ON, I get the correct three voltages at the female connector to the mainboard (I adjusted the power supplies to +8, +16 and -16v). Before I plug any cards in, I like to check to see if the proper voltages are present at the correct S-100 connector pins. Well, they're not. I get no readings from any pin at all. If I connect the DVM to pin 1 and 50, shouldn't I measure +8V? I only installed the S-100 connectors on the mainboard and none of the active termination components. Do I have to add jumpers or something to bypass the missing components? If so what do I need besides the connectors themselves?
toml_12953
 
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Joined: June 7th, 2013, 12:54 pm

Re: 8800c Mainboard problem Mea Culpa

Postby toml_12953 » February 9th, 2019, 3:54 pm

I was in such a hurry, that I forgot to add the three jumpers in F4, 5 and 6. Of course there'd be no voltages on the bus. Adding the jumpers fixed it.
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Posts: 156
Joined: June 7th, 2013, 12:54 pm


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