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Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4062
Hi all.
Seems that with the support being discontinued these are ideal for turning into basic Linux boxes.
Has anyone run into these before? I have one here which has the "flashing lights of doom" and wont display anything, checked and the connector has come off to the screen inverter. Resoldered but still N/G so suspect a power supply issue.
Registered Member #1408
Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679
MANY "computer oriented" electronics are almost unrepairable these days. I decided to repair a flat screen monitor, & YES, it was the power supply. They (Viewsonic) put in the tiniest electrolytic caps they could find (or had manufactured). The specs appeared to be too high for the size. They almost all puffed-up and died. Repairing was very simple but GETTING the commonly available caps to fit was tough. The company went with a custom design to crowd the PS into a small area...stupid.
We are creating vast waste with our attempts at "disposable electronics" & it makes no sense. Repair has always made sense in the past. Trying to work at home with SMD's or miniaturized passive components is a pain in the ass.
Registered Member #3610
Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506
Manufactures make what the customer demands, and the customer demands cheap. How many times have you seen someone go out and buy something because it was the absolute cheapest one they could get?
I've repaired dozens of flat screen monitors and TVs, most of the time it was capacitors. I did have one that I eventually tracked down to an internal fault in one of the main signal processing ICs, couldn't locate a replacement and probably wouldn't have been able to copy the custom firmware over from the old one so I scrapped it. For every fault like this though, there are many others that are simple problems that are easily repaired.
There are various lines of compact capacitors out there, some are short, some are narrow, I've never had too much problem finding suitable replacements from DigiKey or Mouser.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
quicksilver wrote ...
... They (Viewsonic) put in the tiniest electrolytic caps they could find (or had manufactured). The specs appeared to be too high for the size. They almost all puffed-up and died. Repairing was very simple but GETTING the commonly available caps to fit was tough. The company went with a custom design to crowd the PS into a small area...stupid.
I wonder if you have the same viewsonic I had crap out on me. Electrolytic caps bulged, they clearly were seeing high peak current on the SMPS side, with high ESR, they got hot and burst the X on the aluminum top. this caused a small signal diode to fail scorching the board. i replaced the caps and diode with what i found at radioshack, has worked fine for 1+ year now.
Registered Member #3610
Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506
It's certainly not unique to Viewsonic. I've seen exactly the same problem on many different brands, admittedly they were mostly low end stuff.
I did run into an interesting problem once that was only on the Viewsonic flat CRT monitors. Symptom was a blown vertical output IC, replacing that the monitor would work for a number of days/weeks and then the picture width would start to creep up and the vertical IC would blow again.
After tacking on a wire to a bench DMM and using the monitor for a couple weeks, I finally caught the B+ voltage crawling up. Eventually tracked it down to a 4N35 optoisolator with an intermittent fault in the power supply that would warm up and gradually lose output, fooling the power supply into thinking the output was falling which caused the output to rise. I must have fixed at least 10 of these with the same problem, ran into it in the 17, 19 and 22" sizes. PF790, etc.
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(Hacking) Amstrad Em@iler E3
