Possible HV Shutdown Happ Vision Pro MTG-1902EN

[zachary_n]

Hello,

I have a Vison Pro MTG-1902EN VGA monitor that I got from ebay unopened in box and it worked well for about a day and then started making a clicking sound when powered on with no image. It didn't stop functioning in the middle of operation, I plugged it in after use the next day and it just clicked. I'm unable to return it.

I turned the High Voltage ADJ (VR502) all the way to the left

I tested the capacitors with an ESR meter and they all seemed ok and physically look ok

When I discharge the tube after having it powered on for awhile, I do not hear a pop

I disconnected everything from the chassis but power and still hear the click. From searching, I found that some monitors will click when they are in HV shutdown.

Can someone please suggest some troubleshooting steps?

I was thinking of testing to see what the B+ voltage is but I'm no sure where to test it. Below are links to the schematic and manual

schematic: http://na.suzohapp.com/pdf/service_pdfs/support/visionpro/49-1345-vp2_schematic.pdf
manual: http://na.suzohapp.com/pdf/service_pdfs/support/visionpro/49-1345-vp2_manual.pdf


This is the first monitor I have ever troubleshot. Any assistance is greatly appreciated.

Thanks!

Zach


 



 

[ed12]

first problem u have,is u touched the hv-control
this with out proper test eq is a very bad move..
best try to get it back to where it was..
your test point's will be labled tp-1/tp101 or such

ed

[MonMotha]

Also check for a shorted HOT or vert IC.  Most SMPS designs will "tick" as they try to re-crank the B+ line if one if these is shorted.

[zachary_n]

I looked over the PCB for labels that say tp-1/tp101 and I didn't see any.

on the schematic, there is a label that says B+. Should I probe that location? Attached is a screenshot of what I'm looking at.

How can I determine what voltage it should be set to? I didn't see anything obvious in the manual.

Thanks!

Zach

[ed12]

right at the output of the smps
u have 2 coils

L802  123vdc
L803  24vdc
then u have
r808 12vdc
chk there,if they are there ? then move on to the hot,the proper way to do this
is with them in circuit under full load...now if 1 or them is missing open 1 side
of it and see if u get it back?,if so smps is fine,if not u have a smps problem..
with that said place the hv-shutdown control back to where u think it was..
it is never refered to in simple term's in the schematic


ed

[MonMotha]

It's worth pointing out that "all the way to the left" could well mean "crank the HV to maximum", if this is an HV adjustment, or it could mean "set the HV shutdown to minimum" if it's a shutdown threshold setting.  When designing these things, they don't always make the pots behave as you might intuitively expect, especially for controls like this one intended to be carefully adjusted only by technicians.  Either of the aforementioned would essentially force the thing into shutdown even if that weren't the initial problem.