Bad Capacitors – LCD monitor repaired

Bad capacitors are responsible for a number of electronic device failures. Bad capacitors are faulty capacitors (manufactured 1999 – 2007)  that fail prematurely. Bad capacitors have been used in computer mother boards, LCD monitors and other electronics.

The bad capacitor problem is well documented, for example, Wikipedia “Capacitor plague” and Capacitor Lab.

The bad capacitors cause the device that they are in to fail prematurely.  Typical symptoms for motherboards include the PC not always responding to the power switch, failing POST, general instability and crashing of the PC.  Symptoms for a LCD monitor include a delay between powering on and screen startup.

Here are some electrolytic capacitors (these are new good ones):

capacitors
Electrolytic Capacitors. These are the 4 I replaced on the LCD monitor.

The capacitors we are talking about here are called electrolytic capacitors and look like little cans (cylinders) with 2 leads coming out the bottom that are soldered to the circuit board.  You can open up the problem device and inspect the capacitors.  Bad capacitors may show physical symptoms like a bulging top, tilting due to expansion from the bottom, leakage of material from the bottom, discoloration and, in extreme failure scenarios, explosion of the capacitor.  But a failing capacitor may not show physical symptoms.  Test equipment can diagnose failing capacitors.  Also searching the Internet with your device’s model and “bad capacitors” may turn up a history of this problem.

Here are 2 bad capacitors with physical signs of failure – bulging tops:

Bad capicators
Bad capacitors. Note the bulging tops of the 2 capacitors indicating failure.

The case of the failing Viewsonic VA930M LCD

The client reported that the LCD monitor was taking longer and longer to start up.  An Internet search of “Viewsonic VA930M” led me to numerous references to bad capacitors.  Upon opening up the failing LCD, bulging capacitors were noted.  Replacing the 4 capacitors fixed the problem.  The 4 replacement capacitors cost $5.19 + tax.  The time to repair the monitor, about 1 hour.

Turns out there are excellent references on the Internet for this exact repair – step by step instructions for this exact monitor are at LCDalternatives and a YouTube video showing the entire process on a similar monitor. LCD alternatives sells capacitor kits or check out your local electronics supply store for the parts.

Sacramento, California

Update:  In 2015 Metro Electronics closed.  I will miss them.

Here in Sacramento, California I can help you out and I highly recommend Metro Electronics for parts and advice, these guys will help you out.

4 Replies to “Bad Capacitors – LCD monitor repaired”

  1. I do commercial Fire Alarm and restore/repair ‘boatanchor’ amateur receivers & transmitters. Yes, the bad caps are everywhere – most frequently seen “baddies” are Nichicon and Rubycon. Mouser is a splendid source, with DigiKey coming in second. Find a “Soldapullit” solder sucker – the big ones are better, but tough to find these daze [sic]. They even made a chrome one that dissipated static, that I use. Wife’s problem is that her monitor won’t turn OFF, once she “reboots the 117vac” and it turns on – had an ex-wife like that once.

    Tom – W0EAJ – Denver

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