Hi
You could.
It only needs to 'persuade' the air to move a bit so can run slowly.
Put a series resistor (you will have to play with the actual value) and
I suggest a capacitor, say 470 uF in PARALLEL with the resistor. This
would give increased volts to the fan at 'switch on' otherwise there is
a risk it may not start up.
Spacing a fan away from a 'grille' or any other parts reduces the noise.
Matt S
Mike Thompson wrote:
Awesome, thanks guys.
Would it be even better to go a step above and install a quiet fan
into it? Either way this is going to be racked with at least 1U of
space open top and bottom.
--- On *Wed, 5/12/10, Matt Syson /<[email protected]>/* wrote:
From: Matt Syson <[email protected]>
Subject: Re: NEOTEK: Rebuilding a power supply; parts question
To: [email protected]
Date: Wednesday, May 12, 2010, 4:39 AM
Hi
The main killer of power supplies in the long term is HEAT.
Electronic parts are 'happiest' at around 20 - 25 Centigrade and
the closer you can keep ALL the parts to this the better. Of
course to achieve this involves decent airflow and intelligent
placing of parts so that the ones that can tolerate a little more
heat are placed in a suitable position.
Overrating of particularly the 'pass' transistors and the main
rectifier is 'cheap' insurance. In a 'power one' 13 Amp supply
module they run 2N3055 transistors at about 2 Amps per device
which is sensible and I have never seen any failures of these
devices out of what must be over a thousand units. Rectifiers and
occasionally transformers are a different issue.
Remember that heatsink temperature is lower than the temperature
the transistors (and rectifiers) get to so if the heatsink feels
too hot to touch (or hold comfortably) then the transistors are
probably being run a bit hard. Here, having multiple devices helps
spread the strain as the interface between the transistor and the
heatsink, using an insulating washer can allow significant
difference. Make sure you have effective thermal compound in there
and the screws are tight.
With shortage of studio space and the fact these supplies are
silent it is tempting to hide them away somewhere. They MUST have
good cooling airflow.
Matt S
Ike wrote:
> Hi David
> No daggers from this quarter! The only thing I would add
is that what I have found with over a dozen PS-3's that I've known
is that the failures are almost entirely due to assembly problems.
IOW the parts that fail tend to do so because they weren't
soldered and/or mounted properly at the factory. Once these things
are corrected they can and do run for years without any trouble.
> Best
> Ike Zimbel
> Zimbel Audio Ltd
> 416-720-0887
> www.zimbelaudio.com
> Sent from my iPhone
>
> On 2010-05-11, at 11:29 PM, David Butler <[email protected]
</mc/[email protected]>> wrote:
>
>> As a former power supply engineer I will weigh in here, all the
while watching my back for daggers!
>>
>> :-)
>>
>> In general, PSU designers do NOT underrate components enough,
IMNSHO. This is why so many power supplies dies early, untimely
deaths. The capacitors in particular, tend to bake. If higher
temperature caps can be found, so much the better. In general,
going up a little in voltage rating on caps is OK, SOMETIMES going
up in value is OK too, depends on the design. The idea all around
is that heavier is GENERALLY better. You don't want to go
extremely high on capacitor voltages: they are happiest on a diet
of 50% or so of their nominal ratings.
>>
>> The power transistors can sometimes benefit from having higher
voltage, power and current ratings, as long as everything else
(gain especially) is the same. Personally I like rectifiers rated
at at least double, if not triple, the PEAK voltage in the
circuit. Again, rating for higher temperature handling rarely hurts.
>>
>> If the supply in question lasted a long time with no problems,
there is no fault to be placed on using exact replacements
either. My own take is to be conservative by going for heavier
parts if the costs are not excessive.
>>
>> Just my 50 cents...
>>
>> db
>>
>> -- David 'db' Butler
>> AV Wizard, Audio Guru & Team Leader delivering exceptional
>> on-time & under-budget results with cutting edge technologies.
>>
>>
>> Quoting Mike Thompson <[email protected]
</mc/[email protected]>>:
>>
>>> I have a question regarding parts replacement -
>>>
>>> i have a tech who has looked at my Series 1E power supply and
told me he could rebuild it with no problem, but I wanted to make
sure before I handed it off to him if there were any parts that
needed to be specific values (equal to or greater), anything that
should specifically be improved upon when rebuilding, how to make
it compliant to the standard, or any other tips to make sure I
get the most out of it. I know some of you guys had rebuilt them
and I figured this was the best place to ask. Let me know.
>>>
>>
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