Applevision 1710 M2935 monitor dead

[Les Garwood, D.O.]

Hi,
I used to be an electronics repair technician in a former life, and continue
to do repairs for friends and families.

I have an otherwise pristine-looking Applevision 1710 monitor that is as
dead as a cement block. I want to resurrect it b/c my son needs it for his
home/school computer and because I hate to discard potentially salvageable
gear.

So far: Fuse OK, AC traceable on main board, power switch completely OK
(Power LED does not light, incidentally). There is not a millivolt of D.C.
anywhere on the chassis that ought to have some. I have tested it both
attached and unattached to a PowerPC 8500 Mac which is known good, via
another monitor. I can't tell if the CRT filament is burning. And, of
course, Apple being what they are, there is no schematic available outside
of the CIA headquarters.

I've read some interesting snips from anatekcorp.com site that speak about a
Sencore adaptor that is supposed to allow the unit to power-up (providing
it's capable of it otherwise), and about a Triac optoisolator, MOC2A60. The
latter widget has to be turned on in order to power up. Apparently, the
whole thing is a complex loop consisting of a microprocessor, Triac thingy,
and a sensing circuit. An article suggests jumping the settings, and refers
to "Apple's Service Source Companion CD".

So part of my problem involves what to do about the above info, and what
else can I do? I don't have a companion CD or a Sencore adaptor.

Any suggestions would be appreciated.

TIA

Les Garwood

 

[Zeljko]

I repaired one with same symptom...I think I have some manual or schematic.

Problem was in power supply - I forgot where - I will see tommorow.

You can short this opto triac (there is datasheet somewhere on the net).

Use an 100W lamp in series with mains power for the first switching on !!!

Do You hear any quiet c..c..c.. noise...?

Zeljko

 

[Zeljko]

I had a problem that PTC resistor in power supply primar circuit was broken.

This is square blue J29P190 for supplying TDA4605 and TL431, not the big PTC
for degauss!
It has a 1.5K/2W resistor in series, and You must have 11.5V at the cathode
of TL431. I think that this PTC alone has a resistance of 5kohm when cold.

Before giving up also check rectifier diodes in secondary of power supply
for shorts. Check HOT for short also, and other power components - fets,
diodes and transistors!

You can short optotriac and try, even when You check this PTC. Optotriac has
4 pins - two close on the left (LED) and two rather distant on the right
(A1/A2 of the triac). Short this two distant pins on the right.

I started with shorted optotriac and later (after PTC change) removed short,
and it works even today....

Monitor needs an signal in order to turn on.

Zeljko