Re: Slots not working

[supertimer@aol.com (Supertimer)]

Rubywand <rubywand@swbell.net> wrote:
>
>Supertimer writes ...
>> 
>> I had a ROM 1 GS motherboard which worked fine except the slots
>> did not work.  When a card was plugged in and the control panel was
>> set to YOUR CARD, the slots were still seen by the GS as empty.
>> ALL the slots had this problem EXCEPT the memory expansion slots.
>> What was wrong with this motherboard?
>
>
>    If you are saying that, whatever the card and whatever the Slot, the
>cards plugged into the GS's Slots did not work, then, there are a few
>halfway decent suspects on a GS that, otherwise, seems to work okay:

Yes, cards do not work in any slot.

> 1. A break in the trace which is supposed to supply +5V to each Slot
>card would shut down nearly any Slot card.

The LEDs on cards that have them light up, so I think power is still
getting through.

> 2. Most Slot cards need to receive and/or send information over the
>Slot Data bus. A defective 74HCT245 (IC UF2) or one with a loose/broken
>pin connection would be likely to kill Slot Data bus transfers.
>
> 3. A defective Slotmaker chip (IC UE11) or one with a broken trace on
>any of several inputs would render most Slot cards non-functional.
>
> 4. A break in any of several traces supplying signals to the Slots
>would disable many Slot cards.

I'm leaning towards one of these suspects.

> 5. Many Slot cards would not work should any of several Slot traces be
>shorted to another trace or to ground. (Sources of shorting include bent
>case shielding below or behind the motherboard, a Slot socket into which
>a shard of metal, solder, or bit of wire has fallen, a shorted bypass
>capacitor, and, possibly a Coke, etc. spill leaving conductive residue
>beneath several Slot sockets.)

Nothing shorted the traces based on visual inspection.

> 6. If a defective Slot card is plugged into one Slot while other Slots
>are being tried with other cards, the defective card could short or
>corrupt critical bus lines and render other cards non-functional.

The cards all work when plugged into a working GS, so this is not the
problem.  Overall, I suspect one of the ICs you mentioned is the
problem.  Too bad the ICs are machined soldered in such a fine way
that I can't imagine anyone could hand desolder the chips and hand
solder replacement ones on them.  Thank you for the information!