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Andy K
Posted: Tue Dec 18, 2007 7:07 pm Reply with quote
Frequent contributor Joined: 14 Jun 2005 Posts: 3520
Yeah I don't think I have heard of this drop over time before on the toppy, or have I ?


When fitting a new cap you could tilt it away from the HDD to prevent heat problems.

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MikeyP
Posted: Wed Dec 19, 2007 10:25 am Reply with quote
Frequent contributor Joined: 17 Jan 2006 Posts: 4818
Andy K wrote:

When fitting a new cap you could tilt it away from the HDD to prevent heat problems.


but then you'd be tilting it towards the PSU Wink

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Andy K
Posted: Wed Dec 19, 2007 2:06 pm Reply with quote
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Is it the PSU ! Wink

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MikeyP
Posted: Wed Dec 19, 2007 2:17 pm Reply with quote
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Laughing

nearer the hot parts of the PSU then ? Wink

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MikB
Posted: Sun Dec 23, 2007 2:51 pm Reply with quote
Frequent contributor Joined: 23 Sep 2006 Posts: 286 Location: West Midlands
MikeyP wrote:

if it's the caps you're after get some decent (nichicons are my favourites usually) quality (usually gauged by how much you pay for them) radial 1000uF/105degree electrolytics in 16V, 25V or 35V should all physically fit in the spot and be perfectly aok.
(16V as a minimum and 105 degree as a minimum)


Also look for "Low ESR" (Equivalent Series Resistance). These are ones that are not only designed for hot use (105'C) but also are very good for high frequency switching power supplies, like Toppy uses. Not all 105'C caps are low ESR too.

This particular failure mode -- where the capacitors just quietly drift off due to age/drying out -- usually causes the PSU to fail to regulate properly under load, and then pack up altogether. The capacitors may measure OK for value (in 1000's of uF) but you need an ESR meter to check for ESR drifting up. It's easier to replace them and be done with it.

Heat will be a major factor here in accelerating this.

I've had it happen to 2 different LG VCR's (both re-capped and working years later), and a number of DELL TFT screens (all shut down and wouldn't play). It's good to know that it's a simple fix if it happens.

Now I'm out of warranty, I'd be in there with a soldering iron at the first sign of trouble Smile

The capacitors should be available from Maplin (if you're lucky), if not CPC and Farnell are guaranteed to have something suitable.
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Andy K
Posted: Sun Dec 23, 2007 3:45 pm Reply with quote
Frequent contributor Joined: 14 Jun 2005 Posts: 3520
If you find any CPC order codes, they would be gratefully recieved.

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MikeyP
Posted: Sun Dec 23, 2007 3:55 pm Reply with quote
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Andy K wrote:
If you find any CPC order codes, they would be gratefully recieved.


if you insist on cpc Very Happy , here you go buddy:
http://cpc.farnell.com/jsp/search/browse.jsp;jsessionid=AOWPN5Q4DUOIPQFIAEXJK0Q?N=411+121267+101684&Ntk=gensearch_003&Ntt=1000uF+25v&Ntx=&_requestid=106506

Out of those I'd go for the rubycons Very Happy

One pack should sort out the main 1000uF culprits (in my view) which are c23, c22, c17, c18, c19 as these mostly are directly next to heatsinks.
If you get another pack - there is only one more location for 1000uF you could use it which is c26)

If you want to change them all further values are 50v/470uF c18 c12 and c10

(These are all for the old power supply - I believe there is a new version?)

HTH

As MikB quite rightly says the lower ESR ones are the ones to choose , but they almost always carry a higher price than others.

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scoobydooby
Posted: Mon Dec 24, 2007 9:41 pm Reply with quote
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If the caps 'go' , is there a likelyhood that something else could be damaged due to the psu outputting wierd voltages, or is that the voltages creep downwards until their below limits for the mobo & HDD?

I guess I'm wondering if an advanced replacement of the capacitors is a good idea, before any trouble starts, bearing in mind that my toppy was purchased May 2005. (one of the first Samsung drive versions).

Used to dabble with electronics years ago, so I'd like to think that I'm fairly handy with a soldering iron.

Tony

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Andy K
Posted: Mon Dec 24, 2007 11:31 pm Reply with quote
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I think it might be a little early to start replacing capacitors as a preventitive measure.


Mike - Thanks for the link.

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Shannock9
Posted: Tue Dec 25, 2007 8:50 pm Reply with quote
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EuphoricL: Want to add my thanks for this excellent post.
EuphoricaL wrote:
Because the problem was present on both the 5V and 12V lines I figured the 16V caps where a good place to start and not the smaller caps.
Do you have a schematic, or did you reach this intuition based on 'typical' 5v/12v PSU design?
Duncan
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EuphoricaL
Posted: Tue Dec 25, 2007 10:20 pm Reply with quote
Joined: 14 Apr 2005 Posts: 21 Location: Lancaster
Shannock9 wrote:
Do you have a schematic, or did you reach this intuition based on 'typical' 5v/12v PSU design?
Duncan


Just guesswork/experience. I'd seen similar faults before (receivers/routers/PC PSUs), so knew it was probably a cap to blame. And as the problem was on both the 5v and 12v lines i figured that it would be one of the 16v caps. After that leap, it just made sense to replace all the 16v caps.

Just as an update, the box has been mostly on since i replaced the caps with no problems. I'm really pleased that people found this info useful, gives you a warm fuzzy feeling Very Happy
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MikeyP
Posted: Thu Dec 27, 2007 2:46 pm Reply with quote
Frequent contributor Joined: 17 Jan 2006 Posts: 4818
Andy K wrote:
I think it might be a little early to start replacing capacitors as a preventitive measure.


Mike - Thanks for the link.


I'm in the business of repairing brown goods, I've had my toppy since jan 2006 (2 years) and I have not felt the need to blanket change all those 1000uF caps.
So I wouldn't bother unless your toppy is acting up regularly, it's a cheap 1st fix to see if you still have problems.

Mine is still running perfectly OK (apart from the odd toppy moment we all have Laughing )

they aren't dying of old age IMO , they are simply ocassional dodgy ones in a batch IMHO
as I also have a scrap PSU here (from someones on here that failed) , the caps do not show any signs of real old age , tops aren't bulged in any way , they don't stink of cat**** and they haven't leaked in any other way. Wink

Quote:
If the caps 'go' , is there a likelyhood that something else could be damaged due to the psu outputting wierd voltages, or is that the voltages creep downwards until their below limits for the mobo & HDD?


If the caps "go" below spec (high internal impedance etc) - I would fully expect the problem to exhibit itself in the very operation of the toppy, so you won't be running the unit for too long without realising something is wrong (unless you're a bit stupid)

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g.lloyd
Posted: Thu Dec 27, 2007 4:56 pm Reply with quote
Regular contributor Joined: 11 Jul 2006 Posts: 36
Unfortunately changing the caps suggested did not cure the fault on my PSU, the voltage is still dropping to 4.7V.

Turbosat appears to be still closed, anyone know when they reopen?

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nwhitfield
Posted: Thu Dec 27, 2007 4:58 pm Reply with quote
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They are open today - I spoke with them earlier. But I suspect there may be fewer people than usual to answer the phones.

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MikeyP
Posted: Fri Dec 28, 2007 1:38 pm Reply with quote
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g.lloyd wrote:
Unfortunately changing the caps suggested did not cure the fault on my PSU, the voltage is still dropping to 4.7V.
?


and what's it like with the drive (just the 4 way connector) disconnected?

and is this the original drive ?
and have you tried the drive in a PC?

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