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Old 08 December 2010, 16:10   #24
Registered User
Join Date: Nov 2009
Location: Blyth England
Age: 60
Posts: 683
Originally Posted by FOL View Post
Its a sad shame, that nearly all manufacturers cut costs / corners.
They have a habbit of using caps with 85Deg rating in stuff like PSU's.
This is the only reason they fail. If they had stuck 105Deg caps in stuff, you would not get this problem.

Other problems that can cause venting, is using under rated PSU. The caps in psu vent, causing ripples on the DC line.
This in turn takes out the caps on the mobo. Not a nice death, even for a PC Mobo, .

Aye, if it aint broke, then dont fix it.
Alot of problems are caused by un-needed messing.

After working 11 years in the electronics repair trade.
I can safely say, radial 105Deg caps will always be my main choice.
Never really get any problems from them.
Hi there Fol,

you are certainly right about the use of lower temperature caps for cheapness, maybe the designers didn't take into account that things like the heatsink and fan on CPU's would get clogged with dust over time which in turn would reduce the airflow around the surrounding components. Or it could be the actual manufacturer who changes the specifications to fit within a given price range for the product, either way it does mean that a component failure will more likely happen at an earlier time compared to what it would have been if the higher temperature range was used.

When you think of PC motherboards and what a buyer is going to fit on it and what level of ventilation would the case have etc, you would think that with all those unknowns, the manufacturers would use the best quality caps fit for the temperatures that could be expected within reason.

I hadn't thought about the extra ripple effect from the power supply when the smoothing capacitors have fractured solder around their connections, add that to the load that the motherboard caps would normally smooth out and its looking pretty bleak for the motherboard.

What you say about not fixing things until they are actually broken is so very true, more problems are caused that way and can sometimes be harder to trace if someone has been tinkering instead of leaving well alone but I know that myself and probably most of the folk here, have found that out the hard way at some point in time

This is something that you will already know but may be handy for others.
Its surprising how hard it can be to remove some of those caps due to the large ground plane even with a pace desoldering station, the trick I learned from a card repair operator where I used to work was to also use a soldering iron near the via to reduce the heat loss so that the desoldering iron could melt the solder and suck it out of the via. That works a lot better than taking too much time and overheating the via and causing damage, still takes a bit of practice now and then though.


I rang the local mental health services and told them of your plight, they said Oh NO not Paul, last time we went to help he had us singing Christmas carols for hours.
Those poor staff members start to twitch and stammer when they hear his name or Christmas or carol but especially Amiga. Oh dear they have heard Paul's name being spoken and have gone into the foetal position under their desks and are muttering something about partridges! After that they just went AAAAAARGGGGGGGGHHH and hung up.

Bloody hell Paul, I wish I was that popular


the TV modulator is also one of the common faults, especially when you buy a second hand Amiga where someone has been trying to tune it into their TV and damages the threads on the tuner. (thank goodness for the RGB side of things)
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