HP no backlight

[davg]

Re: HP no backlight

Any way, this is the resistance reading of the OZ9930 with the help of lestr:
https://www.badcaps.net/forum/showth...771#post280771
So I am not sure which reading is correct, yours or lestr.

I have rechecked the resistance on I101 using a fluke meter and they are more in line with lestr
pin 1 - 5.54m
pin 2 - 5.57m
pin 3 - GRN
pin 4 - 5.08m
pin 5 - 5.08m
pin 6 - 138 ohm (stable)
pin 7 - 123 ohm
pin 8 - 1.36m
Any concerns in these readings?

[davg]

Re: HP no backlight

Ha you are right what am I thinking and with Q101 removed the reading is
S-G - 0L
S-D - .67m
G-D - 0L
So I can re solder that back in and start over?? Shoot

[jetadm123]

Re: HP no backlight

Am I reading your chart wrong? For Q101, you're showing 0L, 0L and 20M. "0L" means "out of range". In other words, I don't see anything that reads less than 30 ohms, indicating a short.

[davg]

Re: HP no backlight

If a reading is less than 30 ohms, then it is shorted.

Thanks retiredcaps just wondering about switching action?? I will attempt to locate one locally but I suspect it will proberly be easier to go to China and bring one back lol

[retiredcaps]

Re: HP no backlight

If a reading is less than 30 ohms, then it is shorted.

[davg]

Re: HP no backlight

I notice that on some of your resistance readings for transistors, you use "M" versus "m". What's the difference?

Delete

[davg]

Re: HP no backlight

I notice that on some of your resistance readings for transistors, you use "M" versus "m". What's the difference?

Just a slip of the finger caplock on?? No difference. My meter is auto and most of the readings were megaohms? I just borrowed a fluke 87 lll from my son and some of the readings are different "not much" Am I correct in thinking that Q101 is shorted because I am not reading 30 ohms or is this normal? I believe Q101 may be a switching transister?? Would that make a difference to the reading?

[jetadm123]

Re: HP no backlight

I notice that on some of your resistance readings for transistors, you use "M" versus "m". What's the difference?

[davg]

Re: HP no backlight

Thanks retiredcaps I can see what you mean so sorry. Hope the attachment is easier?

[retiredcaps]

Re: HP no backlight

Your readings would be a lot easier to read if they were like this

S-G - 0L
G-D - 0.5M
D-G - 0.7M

instead of everything on one line.

[davg]

Re: HP no backlight

I have taken Q101 of the board an it would appear that it is shorted. S-G 0L S-D .67m G-D 0L Q101 is a 2N7000 same as Q109. I don't have a replacement so I can't try it

[davg]

Re: HP no backlight

Transistors Q101 S-G 0L S-D 20m G-D 0L Q109 S-G .98m S-D .92m G-D 4.62m Q107 EC 0L EB 99.2k CB 15.7m Q102 EC 29.5m EB 29.5m CB 0L Q103 EC 51K EB 31M CB 0L Q106 EC 99K EB 98K CB 197K Q108 SG .90m SD .90M GD 4.5m I have not removed the suspect ones and all test done as per your instructions post #19

[davg]

Re: HP no backlight

Thanks retirecaps here are the results for the diodes D116 .948 - .547, D111 .546 - 0L D107 .842 - 0L, D 108 .537 - .696, D114 .549 - 0L, D103 .543 - 0567, D101 .543 - 0L, D120 .547 -.951, D121 .547 - .951, D118 .549 - 0L, D105 .547 - .573, D109 .543 - 0L, D112 .543 - 0L, D113 5.37-.696.
D 116, 108, 103, 120, 121, 105, & 113 look suspect and I have not removed them?? I am checking the transistors first and will report when complete.

[davg]

Re: HP no backlight

Any way, this is the resistance reading of the OZ9930 with the help of lestr:
https://www.badcaps.net/forum/showth...771#post280771
So I am not sure which reading is correct, yours or lestr.

Thanks budm neither am I not sure if the test method was the same because there are great differences.

[retiredcaps]

Re: HP no backlight

@davg. If you are game, I circled a number of diodes in yellow and transistors in red. See if any of them are shorted.

It should take you about 10 minutes to test them all.

[budm]

Re: HP no backlight

Any way, this is the resistance reading of the OZ9930 with the help of lestr:
https://www.badcaps.net/forum/showth...771#post280771
So I am not sure which reading is correct, yours or lestr.

[davg]

Re: HP no backlight

Ya I know what you mean Thanks pal appreciate the support from yourself, budm, retiredcaps and others on this great site. I did keep a file on the test conducted and may revisit it sometime down the road. In the meantime I have several of these that I will revisit, some with the same symptoms.

[jetadm123]

Re: HP no backlight

Well, I'm stumped. I can't think of anything else.

[davg]

Re: HP no backlight

Thanks jetadm123 made the connection + side of C122 to pin 3 Q104 no difference?

[jetadm123]

Re: HP no backlight

Actually, connections are shown using a red dot. Therefore, the "+" side of C122 is connected to pin 3 of Q104.