Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Old September 23rd 05, 11:03 AM
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Default Viewsonic P810 Clicking

Make: Viewsonic
Model: P810-2E
Chassis: HV8SA
Other #: TNPH0089-4 (on chassis)

I get a relay clicking sound from RL571 on power-up. No lights, no screen etc'.

I'm relatively new to monitor repairs and would like some help on where to start.

I only have a basic multimeter.

I noticed that certain capacitors (C580, C582, C709) registered +3.8volts on their can tops, whereas no others do.

Is this normal?

Any and all help greatly appreciated.

Regards,

Kev

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Old September 23rd 05, 02:00 PM
 
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99% of the G810 and P810 failures are the flyback.
Do a google groups search for those model numbers and how to test the
most common failure mode of the flyback. It runs about $80 plus S&H.
About 10% of the time when the flyback fails, it takes out other parts
in the hv and power supply.

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Old September 23rd 05, 03:29 PM
 
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kvonb wrote:
Make: Viewsonic
Model: P810-2E
Chassis: HV8SA
Other #: TNPH0089-4 (on chassis)

I had a P810-1M monitor. Im not sure if it is different from yours.
Check the FCC number. Mine is GSS21001 August 1996
It has the same chassis number.
I do have a service manual and schematic for mine.
Check the FET transistor that drives the flyback transformer.
E-Mail me if you need more info.
John

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Old September 24th 05, 07:33 AM
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Quote:
Originally Posted by
kvonb wrote:
Make: Viewsonic
Model: P810-2E
Chassis: HV8SA
Other #: TNPH0089-4 (on chassis)

I had a P810-1M monitor. Im not sure if it is different from yours.
Check the FCC number. Mine is GSS21001 August 1996
It has the same chassis number.
I do have a service manual and schematic for mine.
Check the FET transistor that drives the flyback transformer.
E-Mail me if you need more info.
John
Thanks for the reply John,

My FCC ID is GSS21001 August 1997, so same number but a year younger if that makes a difference.

I've done some testing against a manual that I found on the 'net and it seems that I am getting only 14vDC at Q820 (2SC4620) where I should be getting 125vDC!

This transistor seems to drive IC820 (STR-S6531) which I can't seem to find any information on.

However, when I connect my multimeter between any side of R806 (336vDC) and earth (on volts DC scale), the clicking stops and the degauss circuit seems to operate as normal!

I have the thing in a million pieces right now so I don't know if the screen is actually working when the clicking stops so I can't say for sure, but it seems to temporarily cure the problem.

I'm going to investigate this a little closer but any further help would be greatly appreciated.

Regards,

Kevin
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Old September 24th 05, 09:58 AM
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I got power back to the mainboard, but as predicted the flyback is now the problem.

I'm running through all the supporting components to see if it is merely a supply problem.

Kevin


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Old September 24th 05, 11:27 AM
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I tested the secondary side of the flyback with both diode and resistance tests (+ve and -ve directions), both show open circuit.

The primary side is good.

So I guess it's new flyback time

Any suggestions on where to get one?

Kev.
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Old September 24th 05, 08:02 PM
James Sweet
 
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"kvonb" wrote in message
...

I tested the secondary side of the flyback with both diode and
resistance tests (+ve and -ve directions), both show open circuit.

The primary side is good.

So I guess it's new flyback time

Any suggestions on where to get one?



Actually it sounds like your flyback is just fine, the HV rectifier diode
has a forward drop quite a bit higher than a multimeter can supply, so it'll
test open circuit. If it's testing low impedance then you have a problem.


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Old September 25th 05, 07:23 AM
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Well that's good news about the flyback.

My greatest problem right now is that I cannot test a pulsing voltage.

I have a problem flow chart but I need to be able to test a 0 to 47v pulse and I only have a standard DMM.

Any suggestions on how to do this?

Regards,

Kev.
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Old September 30th 05, 03:42 AM
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Well after a week of messing around I replaced Q690 (IRFPF50) with a 2SK1217 and got power back to the mainboard (power LED on, degauss then into power down mode but no CRT).

I found a blown resistor (r861 .33 1/2w) which supplies 210volts from the secondary side of the main xformer to q855 and the (I think) horizontal & vertical driver (pulse?) circiut, and also to q680 which somehow connects to the flyback EHT_+B and q690.

So now the new q690 is blown and I'm back to the clicking and no power!

Back to where I started.

The flyback seems to test as good after following instructions from people who replied here earlier (thanks for all your help).

Any ideas anyone?

Regards,

Kevin.


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