JVC BM H2000PN-K No Picture Anymore

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lettuce

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[font="Verdana, Arial, Tahoma, Calibri, Geneva, sans-serif"]I have a JVC BM H2000PN-K Broadcast monitor and up until last week was working just fine. Have turned it on today and have no picture at all not even the menu OSD shows up, if i press the overscan button i would usually get red, blue and green lines running across the top of the screen now all i get is 4 white lines. I have removed the case and the light emanating from the necktube is extremely dim which is supposed to be fair bright correct?[/font]

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[font="Verdana, Arial, Tahoma, Calibri, Geneva, sans-serif"]Any ideas what the issue could be[/font]

lettuce2018-09-01 16:04:50
 
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lettuce

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Just a quick update, if i press the 'Check Blue' button on front of the monitor which usually changes the whole screen blue all it does now is change the bottom white line (of the 4 whiles running across the top of the screen) to blue.

Its as if the screen display has collapsed!??
 
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obcd

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Some pictures might be helpfull. If the vertical deflection is dead it usually only shows 1 horizontal line in the middle of the picture tube. Donn't let it run like that 2 long as it can burn in the phosfor of your picture tube. (You can reduce the tht screen voltage to make it less bright)
 
Chopper79

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When you put your hand on the PCB, I was waiting for a shock! I was getting nervous watching it. Be very careful, extremely high voltages in there.
 
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lettuce

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Chopper79 said:
When you put your hand on the PCB, I was waiting for a shock! I was getting nervous watching it. Be very careful, extremely high voltages in there.
Click to expand...

I had the monitor turned off at that point and cycled the power also
smiley20.gif
 
TheDaddy

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I was also a little scared. I am a little worried about helping you. Are you electrically minded ?? I don't want to give you advise and you kill yourself !!!

Dave.
 
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lettuce

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TheDaddy said:
I was also a little scared. I am a little worried about helping you. Are you electrically minded ?? I don't want to give you advise and you kill yourself !!!

Dave.
Click to expand...

Ive discharged tubes before back when i used to have my own cab and replaced the screen, i know to stay away from the anode cup area if the monitor hasnt been discharge but ive only ever come across one monitor that never discharged itself, i think anything after the early 90s appear to discharge themselfs on powering off.

So yeah if you have any suggestions please tell

lettuce2018-09-04 10:19:18
 
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obcd

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My first repair attempt would be the replacement of the vertical deflection ic and some of the electrolytic capacitors surrounding it. Maybe if you can figure out some of the voltages that come out of the power supply section, you might check those for a missing one. Usually the vertical deflection ic is bolted to the chassis or attached to it with a clamp so that it gets some cooling. The vertical deflection circuit usually works on one of the lower voltages like 12V or 18V. You might be able to find a datasheet of the chip with some reference schematic of how it should be implemented. It's usually not exactly how it's done in the monitor, but it gives you an idea. Another interesting thing to have is the service manual. If the fault is a HTFE (hard to find error), having it is essential for a good repair.
I assume you know that electrolytic capacitors are polarised and have a maximum operating voltage. If you don't, just find a repair technician and ask him to try to repair it 4 you.

If the vertical deflection ic goes bad, it can take some safety resistor to become bad as well. Sometimes you don't see from the outside that such a resistor burned out. Again, the service manual and schematics come in handy for this.
 
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lettuce

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There appears to be 3 IC type chips inside which are bolted to heat sinks

Im only able to find the service manual for the 14" model....

https://elektrotanya.com/jvc_bm-1400pn-a.pdf/download.html

not sure if everything would be the same between that manual and the 20" that i have?
 
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lettuce

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Actually i noticed further down on that manual pdf it tsupports the BM-H2000PN-K monitor also

I would much rather take it to a TV repairer as they would be able to diagnose the issue 10 times faster than what i would be able to and would have parts on hand to fix it. The only issue is find one in the UK locally anymore
 
TheDaddy

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Hi , Sorry for late reply. I would follow obcd instructions, He is spot on. I am not basing the following on your TV as I have never done one of them but they all have the same parts. I would also first check for dry joints on the vertical control IC (This is normally a 3 pin IC - There will be a couple. Unsure what chip you were looking at in your vid without seeing the circuit diagrams.). Even if they look ok de solder and re solder anyway. There is a cable going to the coils (Red,Green,Blue and yellow I think) check these are all ok and the connectors are ok. Do the same as these normally have dry joints. Do a full cap kit, The TV is old now so would benefit from this either way. If none of the above works then it will be a matter of diagnosing the fault and as you said would probably be quicker sending it to a repair shop. Parts are getting hard to find now.

Hope this help & be careful !

Dave.

P.S this is the second time I have wrote this, First time it errored when I hit ' Post Reply ' !
 
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lettuce

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TheDaddy said:
Hi , Sorry for late reply. I would follow obcd instructions, He is spot on. I am not basing the following on your TV as I have never done one of them but they all have the same parts. I would also first check for dry joints on the vertical control IC (This is normally a 3 pin IC - There will be a couple. Unsure what chip you were looking at in your vid without seeing the circuit diagrams.). Even if they look ok de solder and re solder anyway. There is a cable going to the coils (Red,Green,Blue and yellow I think) check these are all ok and the connectors are ok. Do the same as these normally have dry joints. Do a full cap kit, The TV is old now so would benefit from this either way. If none of the above works then it will be a matter of diagnosing the fault and as you said would probably be quicker sending it to a repair shop. Parts are getting hard to find now.

Hope this help & be careful !

Dave.

P.S this is the second time I have wrote this, First time it errored when I hit ' Post Reply ' !
Click to expand...

Thanks Dave, there is actually a circuit diagram in the manual i posted a link to above, there appears to be 3 IC and 1 IC that isnt bolted to a heat sink, i did reflow solder over the 6 pin IC chip that i highlighted in the video shortly after i took the video but sadly didnt help, i didnt touch the other ICs as the solder looked good.
 
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