Replacing capacitors on Viewsonic monitor power board
I replaced the capacitors
4 x 470uf 25v 1 x 470uf 16v on my Viewsonic VX924 power board, but no joy. Cause? 1. my sad soldering skills 2. problem is elsewhere 3. am I using the wrong type of capacitor? - I don't know what type the old ones were (cross-hatch top) - I bought electrolytic aluminum caps, 565-2449-1-ND and PCE3221CT-ND from digikey.com Any help appreciated. |
Replacing capacitors on Viewsonic monitor power board
What you need is some Vaseline - Sam would knows - He's Dead? - Just a Dumb Hindu "rdr" wrote in message ... I replaced the capacitors 4 x 470uf 25v 1 x 470uf 16v on my Viewsonic VX924 power board, but no joy. Cause? 1. my sad soldering skills 2. problem is elsewhere 3. am I using the wrong type of capacitor? - I don't know what type the old ones were (cross-hatch top) - I bought electrolytic aluminum caps, 565-2449-1-ND and PCE3221CT-ND from digikey.com Any help appreciated. |
Replacing capacitors on Viewsonic monitor power board
On Mar 12, 10:37*pm, rdr wrote:
I replaced the capacitors 4 x 470uf 25v 1 x 470uf 16v on my Viewsonic VX924 power board, but no joy. Cause? 1. my sad soldering skills 2. problem is elsewhere 3. am I using the wrong type of capacitor? * * * * - I don't know what type the old ones were (cross-hatch top) * * * * - I bought electrolytic aluminum caps, 565-2449-1-ND and PCE3221CT-ND from digikey.com Any help appreciated. 1. Do the solder joints look ok? Reflow if not. 2. Sure, you could have another problem, trace the circuit and probe for correct voltages. For example, a transistor may have fried. 3. We are too lazy to goto digikey and input, leave us links and describe where they are in the circuit. Generally, replacements for failed caps tend to be in subcircuits that use very low ESR parts rated at 105C if not higher. Are those? We just don't have enough info, were they in the power supply circuit or elsewhere? If power supply, is the output voltage what it should be? These aren't so much questions for you to answer for us, but rather questions you answer for yourself to decide what to do next. |
Replacing capacitors on Viewsonic monitor power board
rdr wrote:
I replaced the capacitors 4 x 470uf 25v 1 x 470uf 16v on my Viewsonic VX924 power board, but no joy. Cause? 1. my sad soldering skills 2. problem is elsewhere 3. am I using the wrong type of capacitor? - I don't know what type the old ones were (cross-hatch top) - I bought electrolytic aluminum caps, 565-2449-1-ND and PCE3221CT-ND from digikey.com Any help appreciated. Hard to say. What were the symptoms of your failure?? Originally and currently? What made you think the caps were bad? |
Replacing capacitors on Viewsonic monitor power board
On Fri, 13 Mar 2009 16:08:20 -0400, rdr wrote:
On Thu, 12 Mar 2009 23:35:00 -0700 (PDT), wrote: On Mar 12, 10:37*pm, rdr wrote: I replaced the capacitors 4 x 470uf 25v 1 x 470uf 16v on my Viewsonic VX924 power board, but no joy. Cause? 1. my sad soldering skills 2. problem is elsewhere 3. am I using the wrong type of capacitor? * * * * - I don't know what type the old ones were (cross-hatch top) * * * * - I bought electrolytic aluminum caps, 565-2449-1-ND and PCE3221CT-ND from digikey.com Any help appreciated. 1. Do the solder joints look ok? Reflow if not. 2. Sure, you could have another problem, trace the circuit and probe for correct voltages. For example, a transistor may have fried. 3. We are too lazy to goto digikey and input, leave us links and describe where they are in the circuit. Generally, replacements for failed caps tend to be in subcircuits that use very low ESR parts rated at 105C if not higher. Are those? We just don't have enough info, were they in the power supply circuit or elsewhere? If power supply, is the output voltage what it should be? These aren't so much questions for you to answer for us, but rather questions you answer for yourself to decide what to do next.Ww Symptoms were blank pulsing monitor on boot (screen pulsed between black no power, black power, etc). Switching to a working CRT, and switching back to LCD sometimes worked, sometimes not. Power cycling sometimes worked. The caps in question were visibly bulged out. Fix was referenced from he http://www.midnightmods.com/2009/02/...4-vs10162.html Digikey replacement cap links: http://search.digikey.com/scripts/Dk...=565-2449-1-ND http://search.digikey.com/scripts/Dk...e=pce3221ct-nd Caveat: I am electronically ignorant - a complete know-nothing. 1. Joints look ok, for a rookie - I have no way of testing though I'm going to re-solder one more time, and order a replacement power PCB if that doesn't work. Thanks for the feedback! Wow - I re-soldered, and now I'm golden! We'll see how many more years I get out of this - I'm stunned that this actually worked out. |
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