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Replacing capacitors on Viewsonic monitor power board



 
 
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  #1  
Old March 13th 09, 02:37 AM posted to alt.electronics
rdr
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Posts: 3
Default 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.
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  #2  
Old March 13th 09, 03:54 AM posted to alt.electronics
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Posts: 3
Default 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.



  #3  
Old March 13th 09, 06:35 AM posted to alt.electronics
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Posts: 40
Default 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.
  #4  
Old March 13th 09, 12:05 PM posted to alt.electronics
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Posts: 259
Default 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?
  #5  
Old March 13th 09, 08:08 PM posted to alt.electronics
rdr
external usenet poster
 
Posts: 3
Default Replacing capacitors on Viewsonic monitor power board

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.


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!
  #6  
Old March 16th 09, 12:34 AM posted to alt.electronics
rdr
external usenet poster
 
Posts: 3
Default 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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