RUN & WAIT ON All the Time ???

[Walt Perko]

Hi, 

What things would cause both the RUN and WAIT LEDs to be ON all the time on the Don Caprio mini-Front Panel?  

I've tried with different CPU boards and different RAM boards ... same results.  

https://www.youtube.com/watch?v=AZw6mR6sIBw

.

[Patrick Linstruth]

Would need to look at the schematic. It would tell you what could cause that.

It sounds like PRDY is low and RUN is high or the LEDs aren’t displaying correctly. Have you tried scoping out those signals on the MiniFP to verify the LEDs are displaying correctly?

What happens if you press RUN and then STOP?

Additional information might help. Working before and not working now? New board that has never worked before? CPU cards are known to be good? New backplane?

Sent from my iPhone

On Mar 20, 2026, at 4:56 PM, Walt Perko <r4r...@gmail.com> wrote:

Hi, 

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[Walt Perko]

Hi, 

I hate getting old ... I thought I scanned and checked my soldering the mini-Front Panel, but I guess I got distracted and forgot.  Now the computer is much closer to working.  

Currently, I can EXAMINE and EXAMINE NEXT though RAM, but I can only DEPOSIT into 0000 

https://www.youtube.com/watch?v=pSRwRR2j47s

This is all the doc's I have for the Don Caprio mini-Front Panel and I'm not sure which is exactly correct for the version board I have.  

.

[Walt Perko]

Hi, 

C3 is 0.001µF in the schematic ... C4 is 0.01µF in the schematic ... c8 is 0.1µF in the schematic.  

This BOM on the S100Computers website is wrong for C3 and C8 : https://www.s100computers.com/My%20System%20Pages/Mini%20FP%20Board/FP%20Parts%20List.pdf

After looking at the original BOM and high-resolution images of my other boards and the schematic, I've updated my BOM for the Don Caprio mini-Front Panel board, but I'm still not sure it's 100% correct.  

BTW, the BOM shows RR7 as 4.7KΩ Resistor Array, but I don't know how to identify RR7 on the schematic.  It looks like the schematic wants 47KΩ, but I think it was determined that it should be 4.7KΩ ... This needs to be verified by other working Don Caprio mini-Front Panel boards.  

.

[Patrick Linstruth]

RR7 is located on the bottom left of the schematic. It is 47K (47000).

To view this discussion visit https://groups.google.com/d/msgid/Altair-8800/c71c4d61-aaf7-4fef-ba58-5d18741abee1n%40googlegroups.com.
<Don Caprio mini-Front Panel UpDated.xlsx>