viewsonic viewpanel vg150 bad sm caps

[kc8adu]

this unit came in dead.
noticed the dc-dc converter stage wasnt running.traced it to an open 22@16 sm lytic.
tested every sm lytic on the board.all open.
replaced all with sm tants and works perfect now.

[arneson]

Re: viewsonic viewpanel 150 bad sm caps

I know how bad this question is but,, What could have been the cause?

[gonzo0815]

Re: viewsonic viewpanel 150 bad sm caps

I know how bad this question is but,, What could have been the cause?

Cheap components and bad caps or i am wrong there? may be some bad & quick engineering too. Today it is not that hard to find the cause of problems in SOHO elektronics.

[kc8adu]

Re: viewsonic viewpanel 150 bad sm caps

just cheap junk parts in a hot unit.
lg is the worst for these cap deaths.i see plenty of lcd displays from strongarm robots at a local brewery.2 years and they are sick.
i did some of these 4 years ago with tantalums and they are the only ones in the plant that look good.

[gonzo0815]

Re: viewsonic viewpanel vg150 bad sm caps

Wich tantalums you are using on that units, IMHO some tantalums are not suited for SMPS as they can`t stand rapid charg & discharg cycles.

Some good quality AL caps should last long i sutch a circuit, or are they getting that hot?

[samm]

Re: viewsonic viewpanel vg150 bad sm caps

hi everyone,
First post in here after along search. I have the same monitor VG150 and the same problem of no power.
I have the tools and the background to work on circuit boards, best i can with out schmeatics best i can.
My problem is i am not familiar with the lingo used on this site, so i would like someone to help.
for exapler "lytic" i persume means electrolytic cap, "sm" is surface monut but what is 22@16??
After doing some measurments i noticed that i have 12V at the source and the gate of the first mosfet in the dual mosfet chip IC18,
however at the drains i do not have voltage at all and neither do i have any voltage at the Vcc of any of the chips.
Also what is the STZ0c041, IC20 could not find out waht that was or any datasheet.
If someone can help with answers some or all i know i can do this with some help thanks.

[ketterling]

Re: viewsonic viewpanel vg150 bad sm caps

Samm,

I'm looking for the same information. I thought someone would have responded to your question.

FYI: My ViewSonic ViewPanel VG150 has power and a screen but doesn't have the backlighting. Troubleshooting (swapping parts with a good monitor) tells me it's the high-voltage board (yep, that makes me sound ignorant).

If anyone has comments or suggestions, please post them.

Thanks,
Carl

[gonzo0815]

Re: viewsonic viewpanel vg150 bad sm caps

SM lytic 22@16 means chip type surface mounted aluminium eleltrolytic capacitor with 22uF and 16v.

In generall, i would just replace all those badcaps and any other mediocre cap in there.
Even if you succesfully cheked the voltages with a DVM, badcaps can disturbe the digital circuits on the PCB.