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**Harvey** · 10-30-2007, 06:24 PM

Re: Q-Tec 550W Dual Fan Gold

Originally posted by JEWilson

What is the correct next step?

Throw it away and get a decent PSU ?

**Super Nade** · 10-30-2007, 10:01 PM

Re: Q-Tec 550W Dual Fan Gold

Perhaps you can post a few pics?

**JEWilson** · 10-30-2007, 11:58 PM

Re: Q-Tec 550W Dual Fan Gold

This is and now was, an exercise in doing the right thing and
not taking any short cuts, such as;

Resweating old, dry joints and thinking, ha! it'll be ok - no prob.

Had another go at it - only this time, I cleaned all the joints
and resoldered them and cleaned the board after the job
was done.

Heh! This PSU is up again!

Of course, I haven't checked the PSU with PSU testers and/or
load tested it.

Before anybody comments, I only use these testers to establish
if there is an immediate problem such as a rail voltage
not within regulation or the hold up timer and standy voltage
are not in spec etc.

Given the original signs of distress were bad caps, the fact
I have recapped it with a view to the application scenario
I envisaged, that is, replace the crapper Bestec with something
arguably, a little better and I emphasise little!, I will give the
PSU a run out and test if, even though like most of these low-end
budget PSU - the PSU output specs are ambitious, it is up to
doing the job in the PC which will be it's new home.

Thanks for the input

**RoadKill** · 11-02-2007, 03:20 PM

Re: Q-Tec 550W Dual Fan Gold

why would you waste time with a qtec

**JEWilson** · 11-03-2007, 10:31 AM

Re: Q-Tec 550W Dual Fan Gold

Number of things really

I have been away from servicing and repair for a while
So... better destroy low quality kit than better quality kit.

Also, I am repairing a number of OEM mobos. These come
from HP, Advent, Acer and others.

Inadvertently, they are all powered by Bestec 250W units

The nature of the fault appears to be an overvoltage fault
due to the mobos being paired with these PSU units.

I re-sell these with Q-Tec which I repair and upgrade (to the extent,
I replace the O/P filters with Panasonic FCs) and accrue numbers
where, contingently, I can accuarately assess risk of refailure and
extend a limited warranty - at least that's the plan.

Of course, once you've done five of these Q-TECs, you can get the
job done quick - 'nuff said?

**Harvey** · 11-03-2007, 10:50 AM

Re: Q-Tec 550W Dual Fan Gold

I'd of thought it would be cheaper just to bung in a new PSU - how long does repairing/checking/soak testing a PSU take?

Q-Tec PSU's aren't much better quality then Bestec, and even after going through the whole process of replacing caps and FETs and whatever, you'll still end up with an unreliable PSU.

**JEWilson** · 11-03-2007, 11:40 AM

Re: Q-Tec 550W Dual Fan Gold

Well...

This particular PSU was old and so had solder joint probs...

Nonimally if the PSU does not exhibit problems immediately...
as a preventative meaure, I upgrade the O/P Filters with
better quality cap, such as Panasonic FCs.

This can take about two hours.

For what it's worth (excuse the pun), the Bestec 250W PSU are
put in PCs with Mobos that require more power, at least that is,
where the PC is under heavy load.

Most of the trigem and other OEM boards I have came across have
the 3.3V rail s/c to ground as a consequence of no overvoltage protection
in the Bestec - at least this is what I believe. Net result are symptoms
such as PSU will not start or where it does and/or is forced PS-ON,
s/bridge getting hot, USB problems and the like.

The 3.3V is not regulated on the mobo per se, rather this is delivered
direct by the PSU. The s/bridge and other logic devices are powered
by this rail and will or may have some further regualtion to realise
downstream regualtion requirements such as 1.5V etc. If the
3.3V rail goes overvoltage, the lytics and/or power devices will get
fried and go s/c - the genesis of the problem.

This is my personal observation and hence, I supply these 550W Q-TECs
as they address, what I perceive to be the problem, that is, the Bestec
units are entirely inadequate and barley suffice to power these mobo,
at least that is, those that are Barton or Northwood class boards.

More modern mobos still, of course, may require further power.

Of course, I do not use these myself I should emphasise!

**Harvey** · 11-03-2007, 03:41 PM

Re: Q-Tec 550W Dual Fan Gold

Hmm.. so your supplying crappy PSUs that your not prepared to use yourself...fair enough... but on your head be it when your nice Q-TEC's go bang (which they do) and take out not just the motherboard but everything connected to it and the drives and any USB devices plugged in.

I've seen it happen twice with a Q-Tec, and as far as I'm concerned Q-Tec's are just as much of a time bomb as the Bestec 250W's are.

**gonzo0815** · 11-03-2007, 06:04 PM

Re: Q-Tec 550W Dual Fan Gold

Last 400w Q-Tec i got in my trash pile has not harmed the other components.
The caps where heavily bulged an the system won`t start.

But no way i would put it into my system.

**JEWilson** · 11-03-2007, 06:26 PM

Re: Q-Tec 550W Dual Fan Gold

Fair enough...

Y - I have used these in the past with no problems.

However, most recently, I have had to harden desktop and
server infrastructure as a requirement to meet the (ever
more stringent) standards; audit and insurance requirements
working within this industry incurs, certainly that is, within elements
of the private and public sectors.

And so, I should underline I have to refer to a plethora of
published device characterisitics, design schemas and make
informed judgement calls taking account of marketing, hype
and plain mis-information. So far as fora, such as here,
accrue personal experiences, insight and advice; as with
caveat emptor (buyer beware), the reader is at liberty to
consider the views and opinions of contributors, as frankly,
these views are given freely concomitant to a point,
said views do not establish or determine legal conditions.

As always, securing any/all kit supplied against tamper will prohibit
the worst cases of customer misadventure. As to failures,
the fact I replace the O/P filter caps and do establish the PSU
is functioning within spec., gives me confidence enough to put these in systems
where formerly, Bestecs resided. Albeit low end PSU O/P specs are ambitious,
like for like, the Q-TEC offers better O/P and hence, addresses,
the major fault the Bestec's (in my experience for what that's
worth) create.

Suffice to say, if you consider one against the other, then ex post
facto a recap, I consider the modded QTECs are better and would
risk these going in PCs where less than stringent requirements
are the reality such as kid's PCs etc.

Comparatively, even so, this is (my) largely subjective assessment
as opposed to objective, engineering assessment. It may be for
contributors, a formal engineering risk study, for example,
running the numbers on failures and brands might provide an
instructive, empirical record for subsequent reference?

Anyone - thoughts on this?

I don't think anyone can guarantee against catastrophic
failure can they?

**Spacedye69** · 11-03-2007, 07:13 PM

Re: Q-Tec 550W Dual Fan Gold

ANY power supply that has been completly gone through and tested is much safer than buying a $20 pos off the shelf and just installing. At least you know it works.

**starfury1** · 11-04-2007, 05:11 AM

Re: Q-Tec 550W Dual Fan Gold

Really more a general comments on psu's this post

well know stuff all about them but I guess if a design is crap its crap

on the other hand there are psu's that the short comings of, can be rectified by a recap or possibly an upgrade of FETS whatever.....

Basically the design is sound just the production was crap.

So I suppose it depends which side of the fence the Qtec falls on design wise, if its really worth the time and trouble.

As a learning exercise I suppose its ok even if it is crap, but I am not sure I want to be retro fitting potential crap PSU's to other people's computers myself.

I understand what your saying JEWilson, but as Harvey said "its your choice"
Mediocre it might be but so long as its a "safe" supply in my book

Sure true, any supply could suffer catastrophic failure but you want to make that as a remote chance as possible if you can

me I dont know them so can't really comment on the Qtecs
As I said not the guru,
but there are those that post here that know there nuts an bolts so I do take there comments under serious advisement.

There are some supplies that should just be binned for safety's sake.
Some that should never have been sold in the first place and had anyone
(as in a proper Electrical Authority testing mob...like we use to have)
really been checking these things coming into the country, they probably would never have been allowed in.

I agree spacedye69,
A reworked checked one is better then a $20 POS,
provided it isn't a potential Fire hazard or deathtrap or MB killer type psu thats been reworked

Hopefully we have seen the last of them with newer designs and tighter regs
(I don't know but would like to think so)

Just my thoughts on it.

Cheers

**linuxguru** · 11-04-2007, 08:00 AM

Re: Q-Tec 550W Dual Fan Gold

I don't know about Q-TEC, but generally a known dog is better than an unknown one. For instance, I understand the most common failure modes of L&C/Deer/Allied, and I know how to pre-emptively replace caps, rectifiers, fans, etc. to prevent the most catastrophic cascading failures with those units. So far, it has worked well enough (0 failures on 10+ rebuilt Deers) to have a level of confidence in my rebuilt Deers, which I don't yet have (and may not ever have) for Bestec or Leadman/Powmax, even after rebuilding. Similarly, for Hipro, where I'm batting at 0 fails out of 4 recapped.

My guess is that once somebody has groked the most common failure modes of the Q-TEC, they can also confidently refurbish it without fear of future failures.

**JEWilson** · 11-04-2007, 08:00 AM

Re: Q-Tec 550W Dual Fan Gold

Fair Comment,

These retail new at about 50 dollars US here in the UK.

**gonzo0815** · 11-04-2007, 06:53 PM

Re: Q-Tec 550W Dual Fan Gold

Sure, anyone can do what he want to do by it`s own responsibility.
I think a recapped Q-Tec or L&C can do it`s job in the usual less demanding systems.
And it is probably more responsible then just deploying a new POS without any verification.

I can source Seasonic Ss400FS for abouth 10 -20€ from ebay, some FSP`s for about the same price.

I usually recap (only the critical big o/p caps) those units right before they go into any system.
I know, that in those PSu`s OVP, OCP and OPP is working without problem and their UL / VDE etc. certs are not a bad joke.

I see no reason to use a recapped L&c or similar, if not someone really want it.
Personally i have no problem if people want a cheap POS, after i have explained them the risk and who would bear it.

From my experience, most people thankfully accept my recommendations .
The others follow soon, if their crap PSU has fried all their components.

For newer builds, i recommend & use Seasonic S12 series PSU which are in the range of 50€ to 100€

**JEWilson** · 11-05-2007, 01:57 PM

Re: Q-Tec 550W Dual Fan Gold

As to the Seasonic S12

There are, I believe two flavours, the S12 and the S12 II

I believe the S12 has been phased out per;
http://www.seasonicusa.com/s12.htm but
the S12II is not, as with;
http://www.seasonicusa.com/S12II.htm

Is the latter a revision or new(er) model?

**gonzo0815** · 11-06-2007, 06:11 AM

Re: Q-Tec 550W Dual Fan Gold

It`s only a revision, some minor component tweaks and probably some marketing regroup due to the introduction of M12 and S12 Energy +.
SPCR has done some detailed comparisons.

http://www.silentpcreview.com/article596-page2.html

The heat sinks in the S12 II are now a little less beefy, but on the other side all caps are now from high quality brands, even the smallest one (Rubycon, UCC).
The fan is a little higher RPM model and the cables are now sleeved.

The S12 was equipped with Ost and similar caps. at least the lower power versions.
For the S12 II this is not the case.