Guys,
It's been my experience that these supplies, at least the
PS-3, do not run anywhere near hot enough to need fan cooling. 100% of
the heat damage that I have seen has been due to bad solder joints on
mainly the fuse holders and the pass transistors causing specific
connections to heat up. All a fan will do in that case is possibly
extend the MTBF. Some of the supplies I have rebuilt are in their 7th
and 8th years of nearly constant use.
Best
Ike Zimbel
Zimbel Audio Ltd
416-720-0887
www.zimbelaudio.com
Sent from my iPhone
On 2010-05-16, at 10:36 AM, Mike Thompson <[email protected]> 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]>
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]>:
>>
>>> 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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