green pix with retrace. Zenith A50M91W1 projector.

[Jason D.]

Doing an estimate on this projector with this fault. I know these
possible causes but I wanted to be sure before I condemn it for dud
crt or worth fixing it. This is first zenith projector I come across
with this fault, let alone this model didn't service on. I primarily
work with RCA, JVC and Samsung, occasional Pioneer projectors. This
one I come here for your experiences. Already gave google a whirl on
this model and got results unrelated to this model. Even expanded the
search and still not found what I'm looking for.

Pulled the green CRT board (9-1936) and easily found two 1/4W burnt
resistors, One by the connectors between crt socket & edge of board,
one just inside the heatsink saddle area. None other rest of
components are shorted or opens, tracks are intact. Spark gaps &
capacitors checked ok.

Manufactured: Sept 1998. Chassis part of whole chipboard cabinet, not
the pull out lightbox style.

Thanks,

Wizard

 

[Jason D.]

Once again. I mainly do RCA, JVC, Panasonic, Pioneer projectors and
any TVs. Zenith projector rarely pop up at shop, this is why I ask
for your experiences.

Doing an estimate on this projector with this fault. I know these
possible causes but must be sure by asking your opinions before I
condemn it for dud crt or procced with "fixing it".

Pulled the green CRT board (9-1936) and easily found two 1/4W burnt
resistors. One by the connectors between crt socket & edge of board,
one just inside the heatsink saddle area. None other rest of
components are shorted or opens, tracks are intact. Spark gaps &
capacitors checked ok. Zenith of this model uses odd CRT board
circuit design so I'm bit confused.

Does these burnt resistors mean green CRT is knackered? Few days ago,
I diagnosed RCA projector with bad CRT because I know their design
well. Also Samsung flat CRT tv with leaking CRT (arcing purple
"lightnings" in the gun area. Confirmed both RCA & Samsung with HV
probe.

Zenith projector is manufactured: Sept 1998. Chassis part of whole
chipboard cabinet, not
the pull out lightbox style.

Thanks,

Wizard

 

[ed]

jpero@sympatico.ca (Jason D.) wrote in message news:<3ffdfba9.4086692@news1.on.sympatico.ca>...

Once again. I mainly do RCA, JVC, Panasonic, Pioneer projectors and
any TVs. Zenith projector rarely pop up at shop, this is why I ask
for your experiences.

Doing an estimate on this projector with this fault. I know these
possible causes but must be sure by asking your opinions before I
condemn it for dud crt or procced with "fixing it".

Pulled the green CRT board (9-1936) and easily found two 1/4W burnt
resistors. One by the connectors between crt socket & edge of board,
one just inside the heatsink saddle area. None other rest of
components are shorted or opens, tracks are intact. Spark gaps &
capacitors checked ok. Zenith of this model uses odd CRT board
circuit design so I'm bit confused.

Does these burnt resistors mean green CRT is knackered? Few days ago,
I diagnosed RCA projector with bad CRT because I know their design
well. Also Samsung flat CRT tv with leaking CRT (arcing purple
"lightnings" in the gun area. Confirmed both RCA & Samsung with HV
probe.

Zenith projector is manufactured: Sept 1998. Chassis part of whole
chipboard cabinet, not
the pull out lightbox style.

Thanks,

Wizard

Your tube probably is ok. This set most likely has a projection tube
made by zenith(gray base cap). Zenith tubes tend to arc when the set
is shut off and commonly damages the 120k 1/2w resistor located near
the video output transistor. Extreme cases cause the damage you have.
There are other parts on that board also defective, pay particular
attention to diodes. Usually best to replace board. ed

 

[Jason D.]

Pulled the green CRT board (9-1936) and easily found two 1/4W burnt
resistors. One by the connectors between crt socket & edge of board,
one just inside the heatsink saddle area. None other rest of
components are shorted or opens, tracks are intact. Spark gaps &
capacitors checked ok. Zenith of this model uses odd CRT board
circuit design so I'm bit confused.

Snip

Thanks,

Wizard

Your tube probably is ok. This set most likely has a projection tube
made by zenith(gray base cap). Zenith tubes tend to arc when the set
is shut off and commonly damages the 120k 1/2w resistor located near
the video output transistor. Extreme cases cause the damage you have.
There are other parts on that board also defective, pay particular
attention to diodes. Usually best to replace board. ed

Actually the board is fine, the two resistors are R5145 and R5101 that
fried. The bulk 2W resistor next to heatsink is still good. Replaced
that two and still get green retrace that quickly overwhelms set's pix
(can see menu/picture before green blotted both red & blue out) during
warm up.

Does this helps you with this info?

Cheers,

Wizard