Replacing capacitors on Viewsonic monitor power board

R

rdr

Guest
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.
 
What you need is some Vaseline - Sam would knows - He's Dead?
- Just a Dumb Hindu

"rdr" <no@email.com> wrote in message
news:0bgjr4hsqaqm0apv50e8f4r01n8o89a034@4ax.com...
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.
Click to expand...
 
On Mar 12, 10:37 pm, rdr <n...@email.com> 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.
Click to expand...
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.
 
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.
Click to expand...
Hard to say. What were the symptoms of your failure?? Originally and
currently? What made you think the caps were bad?
 
On Thu, 12 Mar 2009 23:35:00 -0700 (PDT), emailaddress@insightbb.com
wrote:

On Mar 12, 10:37 pm, rdr <n...@email.com> 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.
Click to expand...
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 here:

http://www.midnightmods.com/2009/02/fixing-viewsonic-vx924-vs10162.html

Digikey replacement cap links:

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=565-2449-1-ND

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=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!
 
On Fri, 13 Mar 2009 16:08:20 -0400, rdr <no@email.com> wrote:

On Thu, 12 Mar 2009 23:35:00 -0700 (PDT), emailaddress@insightbb.com
wrote:

On Mar 12, 10:37 pm, rdr <n...@email.com> 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 here:

http://www.midnightmods.com/2009/02/fixing-viewsonic-vx924-vs10162.html

Digikey replacement cap links:

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=565-2449-1-ND

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=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!
Click to expand...
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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