Hi,
Apologies for delay in providing an update — seems work can get in the way
of things sometimes.
As of now, still no change in life of the little M102 - no home screen
menu, no beep, contrast runs through full range from light to dark. LCD
cable tested and retested.
I have validated that
h the boot sequence wants to see.
---
From: M100 On Behalf Of perhaps...@gmail.com
Sent: Friday, July 17, 2020 1:15 PM
To: m...@bitchin100.com
Subject: [M100] Troubleshooting M102 (Was: M102, Black Screen, Help!)
Thanks Jeff. I have rev
my 2 cents;
Worth it to see if you have valid signals at both the main ROM and at each
of the installed rams but most importantly the "top 8k". meaning the 8K RAM
that is closest to the system socket.
if there happens to be a cracked track on the PCB, that affects the memory
subsystem, you will
Thanks Jeff B, & Bert P.
I will review the note from Ian, and in the meantime did recheck the CPU
(using a logic probe and my BK Precision multimeter).
Crystal Oscillators
- X1 = 32.76 khz
- X2 = 4.916 mhz
M19/CPU
- #1 = constant signal
- #2 = 4.916 mhz
- #12-19 (AD0-7) =
>>Cheers,Bert (not Jeff :-)
There can never be too many Berts, Birts, Burts,
Jeff Birt
i.e. the machine will not boot. If the screen is blank, blind type in
‘beep’ and press return. If this works you know the machine is booting
Press Enter once to get into BASIC first.
--
bkw
nts to see.
---
From: M100 On Behalf Of perhaps...@gmail.com
Sent: Friday, July 17, 2020 1:15 PM
To: m...@bitchin100.com
Subject: [M100] Troubleshooting M102 (Was: M102, Black Screen, Help!)
Thanks Jeff. I have revisited all the documented diagnostics in the servi
Hi Alan,
I'm with Jeff on this one. So far you've shown that you've tested
voltages, cables, even the LCD contrast pot, but you haven't really
talked about the logic side. You mentioned you replaced all the RAM
(even installing sockets), as well as re-capping the board, but so far I
haven't
Hi Matt
Thanks. I have found similar issue with the LCD cable on the ends,
corrected and carefully reinserted. I will take another look, and redo
continuity from connector to connector.
If I can find a flat ribbon with the correct specs, I’ll also try to order
a replacement.
Here’s to hoping I
Hi Alan,
I was working through a similar issue recently. Fortunately, I had access
to a logic analyzer and was able to confirm that the CPU was operating
properly, and even where in the ROM it was looping. Once I was able to
determine it was waiting for the LCD status to change, I rechecked the
Thanks Jeff. I have revisited all the documented diagnostics in the service
manual, and checked/re-checked all the voltages, reset circuit and LCD.
The current state is that the system has correct voltages in both
power-on/memory-on and power-off/memory-on modes. The LCD works, in as much
as it
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