Hello,

I'm quite new to electronics repair but I believe I do have a basic
understanding of things. I've spent the better part of today
troubleshooting a dead monitor. The monitor is an HP Pavilion v70,
model number: P3209S, chassis: Tatung C7Es.

I've followed the FAQ a bit and tried to determine what I should do but
I've gotten stuck. Over the past couple of weeks the horizontal
deflection would cut out occasionally (wouldn't come back with a gentle
whack) and would be fine after shutting it off to rest for a few
minutes. Also, the picture's vertical deflection would squash down
about an inch on top and bottom, but this could be fixed with a gentle
tap, so I suspect it was just a loose connection.

A couple days ago it decided that it would not power up at all. There
are no indications of power (no static, no clicks, no lights, etc.)
Upon opening the case and plugging it in, if I listen closely I hear it
clicking quietly like a clock (as in the FAQ.) I've tested the HOT and
it appears to be shorted out and I don't measure voltage on it. I'm
not sure I'm measuring it correctly, but I'm putting my black lead on a
ground and the red lead on each leg of the HOT. I read 0V on each one.

Now, I've come to the conclusion that I should replace the HOT, but I'm
not sure if this is the right course of action, nor am I sure if it's
the full problem. I'd like to know if I've done everything correctly
and what I should do next. I have access to a multimeter, 100MHz
oscilloscope, and an ESR meter. If there is any information that I'm
missing, I'll be happy to give more details if I'm able. I'd
appreciate any help in repairing this monitor.

Thanks!
James Bailey

You have a long way to go, but you sort of have the right idea. It would be
beyond the scope of emails to fix your monitor using emails.

You can heat the caps with a heat gun, and when warm, you can do the ESR
testing. Many of the caps go high in ESR when they are warm. The ESR test
is best done when both warm and cold.

Just keep in mind, that if you have a piece of equipment, and it is changing
specs over a period of time, from when it was turned on, this means that
there is something that has become thermo sensitive. If you give something a
wack, and it starts to work, this is an indication that there is a cold
solder connection, or something is making poor contact.

The horizontal output transistor (HOT), is best removed for testing. There
are very low resistor values, and components of low resistance that are
connected to the HOT, and thus, your ohm meter will not be practical to use
to test it properly. Use the diode test option on your DVM to test
semiconductors. If the HOT is a FET device, then it can get a bit tricky to
do a simple test. Most of the time, when a HOT goes bad, it is usually
shorted from the emitter to the collector. In the case of a FET, this would
be from the source to the drain.

When troubleshooting any piece of equipment, start with the power supply
first. In the case of a monitor, the next step is the high voltage (HV)
area, and the scan amplifiers.

As for learning, TV equipment is about the worse to start with. The modern
day TV sets and monitors, are very complex to start with. Even the sets of
many years ago were not very simple.

Working on computer monitors is even worse than standard TV sets. The
manufactures will not sell any service parts, and service manuals to any non
contracted service people. In many of the cases with the new monitors, they
are servicing them mostly at the modular level now. The cost of the labour,
parts management, and the added training is too great in relation to
changing a complete board while the unit is under warranty. After warranty,
for the end user, a monitor can be too expensive to service.

Just take care for proper safety issues when working on display equipment.
The power supply in a monitor or TV set can easily badly injure someone, or
take their life. This type of work is a serious matter.

--

JANA
_____


wrote in message
ups.com...
Hello,

I'm quite new to electronics repair but I believe I do have a basic
understanding of things. I've spent the better part of today
troubleshooting a dead monitor. The monitor is an HP Pavilion v70,
model number: P3209S, chassis: Tatung C7Es.

I've followed the FAQ a bit and tried to determine what I should do but
I've gotten stuck. Over the past couple of weeks the horizontal
deflection would cut out occasionally (wouldn't come back with a gentle
whack) and would be fine after shutting it off to rest for a few
minutes. Also, the picture's vertical deflection would squash down
about an inch on top and bottom, but this could be fixed with a gentle
tap, so I suspect it was just a loose connection.

A couple days ago it decided that it would not power up at all. There
are no indications of power (no static, no clicks, no lights, etc.)
Upon opening the case and plugging it in, if I listen closely I hear it
clicking quietly like a clock (as in the FAQ.) I've tested the HOT and
it appears to be shorted out and I don't measure voltage on it. I'm
not sure I'm measuring it correctly, but I'm putting my black lead on a
ground and the red lead on each leg of the HOT. I read 0V on each one.

Now, I've come to the conclusion that I should replace the HOT, but I'm
not sure if this is the right course of action, nor am I sure if it's
the full problem. I'd like to know if I've done everything correctly
and what I should do next. I have access to a multimeter, 100MHz
oscilloscope, and an ESR meter. If there is any information that I'm
missing, I'll be happy to give more details if I'm able. I'd
appreciate any help in repairing this monitor.

Thanks!
James Bailey

wrote:
Hello,

I'm quite new to electronics repair but I believe I do have a basic
understanding of things. I've spent the better part of today
troubleshooting a dead monitor. The monitor is an HP Pavilion v70,
model number: P3209S, chassis: Tatung C7Es.

I've followed the FAQ a bit and tried to determine what I should do but
I've gotten stuck. Over the past couple of weeks the horizontal
deflection would cut out occasionally (wouldn't come back with a gentle
whack) and would be fine after shutting it off to rest for a few
minutes. Also, the picture's vertical deflection would squash down
about an inch on top and bottom, but this could be fixed with a gentle
tap, so I suspect it was just a loose connection.

A couple days ago it decided that it would not power up at all. There
are no indications of power (no static, no clicks, no lights, etc.)
Upon opening the case and plugging it in, if I listen closely I hear it
clicking quietly like a clock (as in the FAQ.) I've tested the HOT and
it appears to be shorted out and I don't measure voltage on it. I'm
not sure I'm measuring it correctly, but I'm putting my black lead on a
ground and the red lead on each leg of the HOT. I read 0V on each one.

Now, I've come to the conclusion that I should replace the HOT, but I'm
not sure if this is the right course of action, nor am I sure if it's
the full problem. I'd like to know if I've done everything correctly
and what I should do next. I have access to a multimeter, 100MHz
oscilloscope, and an ESR meter. If there is any information that I'm
missing, I'll be happy to give more details if I'm able. I'd
appreciate any help in repairing this monitor.

Thanks!
James Bailey

I'm sure you are right about the HOT shorted. If it uses thermo grease,
be surer to use a thin even amount (not the liquid y stuff when you
first squeeze it out of tube). Next find the cold solder joint that took
out the HOT. Since you were tapping or whacking it, look at the flyback
for bad solder joints since it's heavy and more susceptible to movement,
look for broken traces on board and check the electrolytic capacitors
for bulges on top and an ESR meter for the others. Good Luck.

Okay, what I've gathered so far:
- Remove HOT and test properly, replace if necessary
- Heat caps and test ESR, replace bad caps

Is this generally all I need to do? Do I need to check for blown
fusable resistors, etc.? I figure I need to do that considering I
don't have voltage running to the HOT (if I'm measuring this correctly
- probe to ground and probe to leads of HOT).

Thanks again!
James