LA210 Schematics - test-drb@ccmp.vtda.org

12 Nov 2005

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Subject: Re: LA210 Schematics
   From: ard at p850ug1.demon.co.uk (Tony Duell)
   Date: Sat, 12 Nov 2005 01:54:04 +0000 (GMT)
     To: cctalk at classiccmp.org

  Easiest
starting point is to check operating voltages.  If during 
printing they drop or go flakey it's the PS.  The fact that it 
prints at all says most of the logic is solid and working.

Allison

  One of the reasons I want some kind of schematic.

 So I can know what voltage levels should be where, and if I find 
There pretty much has to be a +5V line for the TTL, microprocessor, etc. 
You can find that from data sheets on some of the ICs. I'd start by 
checking the voltage between that and logic ground (found on the gnd pin 
of similar ICs). 

-tony 
Easier than that Tony.  Pick a voltage on any line and when it start 
printing see if it changes when the printer fails.  No need to know
what the correct voltage is when it prints because it is likely correct
at that time.  However if the printing stops and the voltage does too
then there is a clue.

FYI: LA210 has a main logic with everything and a power supply unit
of the switching variety.  I do believe there is a power Ok signal
...
 from that supply.  I believe it's derived on the
logic board. 
How if I knew which DEC prints box of the four it's in I could go 
further.

Allison