It could also be M14 or the flux on the PCB has become slightly conductive. 

A friend had M14 act wonky on his T102 recently. Time was screwy until it 
warmed up, replacing M14 fixed it. A M100 I just did was doing silly things 
with respect to the LPT strobe signal which (which comes from M14). M14 was 
swapped, no changed. Pulled T8 (strobe output transistor) and it tested fine. 
Reinstalled it and things ran fine. 

 

The flux used gets slightly conductive over the decades and I’ve seen it cause 
everything from phantom keypresses to PS not starting up, reset button not 
working, and the latest is the T8 issue.

 

Jeff Birt

 

From: M100 <[email protected]> On Behalf Of Stephen Adolph
Sent: Friday, July 4, 2025 7:58 AM
To: [email protected]
Subject: SPAM-LOW: Re: [M100] M100 garbled screen

 

looks to me like the 32768 hz crystal is dead.

 

On Fri, Jul 4, 2025 at 8:56 AM Thomas Morehouse <[email protected] 
<mailto:[email protected]> > wrote:

Friday update:

 

Batteries replaced with fresh AA alkalines yesterday (Thursday).  Left powered 
off overnight to recharge backup battery.  Powered up this morning, but no 
change.  See attached screen photo.

 

The screen clock seems to be working, but date never changes from 1/1/1900.

Top four lines of screen appear normal, but below that, definitely not normal.

 

The "center" screen line consists of constantly changing characters.  Lowest 
screen line appears to be reiterations of "Bytes free" - without the "Byt".

 

None of the keyboard keys have any effect; when "cursor" is over BASIC, hitting 
Enter changes nothing - screen remains unchanged.

 

I've done several Cold Starts (CTRL+Pause/Break+Reset) and 
(CTRL+Pause/Break+Power switch), but no apparent change.

 

Note:  when I do a Power On, the screen quickly shows the correct original 
default M100 screen, then immediately changes to the garbled screen.

 

Onward through the fog!

Thanks.

Tom M.

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