DIY Power Supply Repair

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Cband55

Cband55

Thread Starter
SatelliteGuys Pro
May 14, 2008
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Does anyone know of help pages to do this, is it as easy as unsoldering a bad Capacitor and soldiering a new one and your done?

If this is it, sounds very easy I hope I dont insult any tv/video rapirmen forum member but anyone could do that.
 
USDownlink

USDownlink

SatelliteGuys Pro
Mar 19, 2008
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Oregon
I suppose if your starting point is knowing that the bad part is indeed a capacitor, and you already know which one, then sure, the next step to fixing it is to replace that part. It's not always a trivial task getting to that point, however.

A service tech would/should have the experience to know that in a particular power supply, a certain part is prone to failure, and can fix many if not all of the ones that come his way. Or, perhaps in the case of an electrolytic cap, one that has 'outgassed' is rather easy to spot even for the untrained eye. But the more subtle the problem becomes, the more experience in troubleshooting circuits becomes a requirement.

So let's say you are looking at a cap that has obviously failed. Sure you can replace it as easy as you suggest, but the next question might be what caused it to fail, and will that be an issue with the replacement cap as well? Fortunately this question is easily answered: the replacement cap either works for a long time or it blows up again quickly. The "real" repair in the latter case is much more involved, naturally.
 
qwert1515

qwert1515

SatelliteGuys TheList
Sep 26, 2005
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It is fairly easy if you have ever done soldering before, otherwise you should practice a little bit on a board that you do not care about.

First you have to de-soldering the old capacitor using a soldering iron and a de-soldering wick or gun and then solder a new one in its place, with the same values (The voltage rating of the capacitor can be higher (as long as it fits in the same place) but you want to have the same capacitance rating (usually in micro farads "uF").

If you send me a PM with your email address I can email a fairly good guide for replacing capacitors in the Pansat 3500. (I believe the guide came from a hack site so that is why I am not posting it to this thread.)
 
ynnedibanez

ynnedibanez

SatelliteGuys Pro
Dec 7, 2009
536
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Greeneville, Tennessee
a couple things to consider first,
it is quite common that if an electrolytic capacitor in a power supply has died, it is because 1 or more diodes have failed and if you just replace the capacitor, it will fail again.
also, mind your polarity, electrolytic capacitors can explode quite violently if wired up backwards.
also, make sure that the max voltage of the replacement capacitor is as high or higher than the original.
hope this helps,
Denny
 
Last edited:
Inno

Inno

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Aug 13, 2006
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NW Ontario, Canada
Does anyone know of help pages to do this, is it as easy as unsoldering a bad Capacitor and soldiering a new one and your done?

If this is it, sounds very easy I hope I dont insult any tv/video rapirmen forum member but anyone could do that.

I'm sure there are help pages that will teach you the basics but if you are looking for equipment specific info you probably won't find it.
I guess if we knew just what it was you were looking at there are a number of us with some experience in this field. I for one worked as a tech. for a number of years.
Descriptions, measurements, observations and pictures would be a great start. :)
 
USDownlink

USDownlink

SatelliteGuys Pro
Mar 19, 2008
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also, make sure that the max voltage of the replacement capacitor is at least a little higher than the power supply's output

Gak. Use qwert's approach, please, and use at least the same voltage rating as the one you removed. Some supplies have high voltage intermediate stages.
 
Inno

Inno

SatelliteGuys Pro
Aug 13, 2006
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NW Ontario, Canada
I think what he meant here was that if you remove a 16V cap. replace it with a cap. rated at 16V or a little higher. For example if it is a filter for a 12V circuit, put in at least a 16V cap. Personally I'd put in a 25V in that case just for longevity. Manufacturers often will put in caps that are barely big enough just to save a few fractions of a penny on each unit. Over thousands or millions of units these savings add up.
 
ynnedibanez

ynnedibanez

SatelliteGuys Pro
Dec 7, 2009
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Gak. Use qwert's approach, please, and use at least the same voltage rating as the one you removed. Some supplies have high voltage intermediate stages.
right, just so long as the voltage on the replacement capacitor is at least as high as the original it should be fine.
i should have worded it like that instead;)
 
ynnedibanez

ynnedibanez

SatelliteGuys Pro
Dec 7, 2009
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Greeneville, Tennessee
I think what he meant here was that if you remove a 16V cap. replace it with a cap. rated at 16V or a little higher. For example if it is a filter for a 12V circuit, put in at least a 16V cap. Personally I'd put in a 25V in that case just for longevity. Manufacturers often will put in caps that are barely big enough just to save a few fractions of a penny on each unit. Over thousands or millions of units these savings add up.

exactly, thanks:)
 
dougbrown

dougbrown

SatelliteGuys Guru
Mar 31, 2005
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Southern WI
there has been a rash of bad caps over the past several years which has caused a lot of motherboard failures. Probably caused problems with a few STB's as well.
 
I

Ironsides

SatelliteGuys Pro
Dec 4, 2008
319
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North Carolina
You should

You should talk to McGuyver about this, he is Very VERY smart about power supplies..
 
Anole

Anole

SatelliteGuys Master
Sep 22, 2005
11,819
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L.A., Calif.
A very long time ago, I repaired several computer motherboards that died too young!
Not a lot of fun, due to the problem finding parts the right size.

I forget what brand receiver I fixed last year.
Just identified one or two bad caps, and replaced them.
Problem solved.
There was room to put in larger physical parts without causing any mechanical problems.

Several years back our good friend Linuxman had trouble with his... Pansat 3500(?)
We had him look for suspicious parts and he posted pictures.
With the proper feedback, he was able to install new capacitors and bring his receiver back to life.
You could search on threads he's started, if you think it would be helpful.

edit:
More recently, someone posted internal pictures of a Gbox/Vbox which (if I recall) had a blown power rectifier.
We gave him feedback on replacements and I think he got it running again.
(I seem to recall taking one of his very good pictures, and adding notes and arrows, to help)
 
M

McGuyver

SatelliteGuys Pro
Apr 4, 2007
783
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Nuclear Testing Grounds
Does anyone know of help pages to do this, is it as easy as unsoldering a bad Capacitor and soldiering a new one and your done?

If this is it, sounds very easy I hope I dont insult any tv/video rapirmen forum member but anyone could do that.

What receiver are we talking about here?
What do you suspect caused the failure?
Have you ever connected or disconnected the LNB coax with the power on?
Does the stb have any video at all?
If it does, can you navigate the menu?
If you have video, have you lost only the signal from the LNB?
***Some details would help to narrow down the problem.***
 
Cadsulfide

Cadsulfide

SatelliteGuys Pro
Sep 8, 2008
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Cavalier, North Dakota
If you are kinda new at replacing electronic parts, buy a 12 pack of cool refreshing beverages and go visit with a techie pal who is good at it. The training will be well worth it.
 
T

tvropro

On Vacation
Mar 9, 2007
6,872
0
Regular caps are a piece of cake. When you get onto SMD thats where it becomes a pain
 
Tron

Tron

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May 6, 2005
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Metro New Orleans, LA
Thanks Tron for the valuable source link, I may need it sometime :D

No problem, McGuyver! His prices were reasonable with shipping, and he sold individually or in a kit. Since the motherboard issue I was experiencing involved only six caps, that's all I ordered. The others were from a different manufacturer, and therefore had no issues.

Skjellyfetti's link is also a very useful site. TVROPro is right about the surface-mount caps... They are a REAL PITA. Many of the broadcast-grade VTRs made by Panasonic and Sony have capacitor issues, and they're all surface mount. Rebuilding one of those boards can try one's patience ;) ...
 
M

McGuyver

SatelliteGuys Pro
Apr 4, 2007
783
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Nuclear Testing Grounds
No problem, McGuyver! His prices were reasonable with shipping, and he sold individually or in a kit. Since the motherboard issue I was experiencing involved only six caps, that's all I ordered. The others were from a different manufacturer, and therefore had no issues.

Skjellyfetti's link is also a very useful site. TVROPro is right about the surface-mount caps... They are a REAL PITA. Many of the broadcast-grade VTRs made by Panasonic and Sony have capacitor issues, and they're all surface mount. Rebuilding one of those boards can try one's patience ;) ...

I haven't had any PC cap problems yet but when it comes to FTA receiver PSU's I find that most of the manufacturers use cheap PSU's of much less quality than the mobo's. In every case I've encountered it's always been a PSU failure and I contribute these failures to cheap components. As a rule of thumb I will replace the notorious caps before a failure strikes, this I consider when the STB is about 1 to 2 years old. The caps are commonly rated with a 1000 hr life span and that isn't much for any receiver that is always powered on. I always buy the highest life rated caps available that may be 2000 or 3000 hrs in comparison. Higher temperature ratings is another factor to consider in replacement caps.
 
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