20 Mar
2005
20 Mar
'05
2:58 p.m.
I finally found the info on suggested TU-56 cap repair from the guy who
actually did it with these parts. Here is what he had to say:
The capacitors are from www.newark.com part number
89F2059 with bracket
81F3218
These must be replaced in pairs.
Attached is a JPG of the mounting plate made from a 1/16" thick aluminum
plate. The image should be to scale. The height is 5" and width is 4.3"
The plate is attached using 0.5" 8-32 standoffs from www.digikey.com part
number 8427K
You will also need 1/4 and 3/8 8-32 screws.
Note that the caps he found & used are slightly different size than the
originals, hence a different mounting plate and brackets.
Hope this helps everyone! I can put the .jpg file refered to up if people
want to see that too.
Jay West
20 Mar
20 Mar
3:46 p.m.
It would appear they are cheaper than $70 bucks each.
I think what had stuck in my brain was I knew they needed to be replaced in
pairs, and with one bad one I knew I'd need two - so my brain recalled the
total price ($70 for two, not one).
Regards,
Jay
5:22 p.m.
From: "Jay West" <jwest at classiccmp.org>
I finally found the info on suggested TU-56 cap repair
from the guy who
actually did it with these parts. Here is what he had to say:
> The capacitors are from www.newark.com part number 89F2059 with bracket
> 81F3218
>
> These must be replaced in pairs.
Thanks! The capacitors seem to be basically the same as the ones currently
on eBay (auction 7500675454 or 7501263567) for about $10.
It is interesting to see a part number for the mounting clamp (though $1.80
each seems a little steep).
> Attached is a JPG of the mounting plate made from
a 1/16" thick aluminum
> plate. The image should be to scale. The height is 5" and width is 4.3"
>
> The plate is attached using 0.5" 8-32 standoffs from www.digikey.com
part
> number 8427K
>
> You will also need 1/4 and 3/8 8-32 screws.
I assume we screw the plate into place in the TU56 using the standoffs, and
it has holes in it for the capacitor clamp? Or does it bolt directly the
TU56, with the clamp on standoffs?
Seems like the Ebay caps, the mounting plate, and the clamps would make for
a pretty affordable solution.
Newark has a $25 minimum order (to escape the $5 penalty). If desired, I
could order enough of the clamps to meet the minimum order, then ship them
to people who want them. Or someone could try to find them at Home Depot or
somewhere . (A 2.5" inside diameter circular clamp shouldn't be impossible
to find.)
(I think I will order a few capacitors and experiment with mounting
hardware.)
Vince
7:06 p.m.
vrs wrote...
Thanks! The capacitors seem to be basically the same
as the ones
currently
on eBay (auction 7500675454 or 7501263567) for about $10.
...snip...
Seems like the Ebay caps, the mounting plate, and the
clamps would make
for
a pretty affordable solution.
Note that the caps in my TU56 are electrolytic. They are not oil filled. The
two on ebay you mentioned are oil filled.
I have no idea if that makes a difference or not.
Jay
7:20 p.m.
On Sun, 20 Mar 2005 18:06:48 -0600, Jay West <jwest at classiccmp.org> wrote:
Note that the caps in my TU56 are electrolytic. They
are not oil filled. The
two on ebay you mentioned are oil filled.
I have no idea if that makes a difference or not.
Probably not as long as the oil stays on the inside... :-)
-ethan
21 Mar
21 Mar
6:48 p.m.
On Sun, 20 Mar 2005 18:06:48 -0600, Jay West <jwest at classiccmp.org> wrote:
This is not really my field, but I would think you could always replace
an electrolytic by a non-electrolytic (such as an oil-filed capacitor),
but not necessarily the reverse.
-tony
Note that the caps in my TU56 are electrolytic.
They are not oil filled. The
two on ebay you mentioned are oil filled.
I have no idea if that makes a difference or not.
Probably not as long as the oil stays on the inside... :-) 
8:15 p.m.
Tony wrote:
This is not really my field, but I would think you
could always replace
an electrolytic by a non-electrolytic (such as an oil-filed capacitor),
but not necessarily the reverse.
Assuming the capacitance and voltage ratings are the same, that would
probably be true unless the circuit required a minimum or maximum ESR.
Electrolytic capacitors generally have a much higher ESR than
non-electrolytic types, though there are some new (expensive) low-ESR
electrolytics.
Most of the time it is OK to replace a capacitor with one that has
lower ESR. An example where that is not true is filter capacitors on
low-dropout (LDO) linear voltage regulators; LDOs have both minimum and
maximum ESR requirements for the output filter capacitor, and in some
cases the input filter as well, and exhibit oscillation and other
instabilities outside the specified ESR range. That's why I still
prefer normal (non-LDO) linear regulators wherever LDO is not required.
Typically where moderately high capacitance is required with low ESR,
solid tantalum capacitors are used, however there are some potential
problems with tantalums so they are best avoided when not necessary.
(And they are relatively expensive.) Tantalum capacitors will fail
in a particularly spectacular fashion if reverse-biased. One day
when we arrived at work, there was a 3/4-inch hole burned through our
multi-thousand-dollar prototype PCB, and a charred spot on the
workbench below it. Although there was not enough evidence left to
prove it, we believe that a tantalum capacitor had been installed
backwards.
Eric
22 Mar
22 Mar
6:52 p.m.
(And they are relatively expensive.) Tantalum
capacitors will fail
in a particularly spectacular fashion if reverse-biased. One day
when we arrived at work, there was a 3/4-inch hole burned through our
multi-thousand-dollar prototype PCB, and a charred spot on the
workbench below it. Although there was not enough evidence left to
prove it, we believe that a tantalum capacitor had been installed
backwards.
May not have been.... I've had tantalum capacitors 'go up' for no good
reason, they burn spectacularly give off a large cloud of smoke, and
often the remains on the boasrd is glwoing red-hot at the end.
When I say 'no good reason', I mean I've had PCBs that have been used for
say 5 years, then stuck on the shelf for a few months, then they go up a
day or so after putting the board back in service.
They certainly weren't fitted backwards.
-tony
25 Mar
25 Mar
9:20 p.m.
On Tue, 22 Mar 2005 23:52:00 +0000 (GMT)
ard at p850ug1.demon.co.uk (Tony Duell) wrote:
I'll second that notion; tantalums are really nasty parts. Used incorrectly, any part
might fail, but as time has gone by, my impression of tantalum parts is about like
'ticking time-bomb'.
I've seen more than several burninate for no real reason.
--
---------------------------------------------
-. William W. Layer .- -. St. Paul, MN USA .-
---------------------------------------------------
-. Cheif bottlewasher, Atma-Sphere Music Systems .-
-. http://www.atma-sphere.com .-
--------------------------------
Although
there was not enough evidence left to
prove it, we believe that a tantalum capacitor had been installed
backwards.
May not have been.... I've had tantalum capacitors 'go up' for no good
reason, they burn spectacularly give off a large cloud of smoke, and
often the remains on the boasrd is glwoing red-hot at the end.
20 Mar
20 Mar
7:26 p.m.
vrs wrote...
I assume we screw the plate into place in the TU56
using the standoffs,
and
it has holes in it for the capacitor clamp? Or does it bolt directly the
TU56, with the clamp on standoffs?
the plate jpg is located at www.ezwind.net/jwest
Jay
7:56 p.m.
From: "Jay West" <jwest at classiccmp.org>
Interesting. Seems like there should be more holes (assuming the one plate
is for both caps). What's the resolution on that picture? 300dpi? (Maybe
if I could print it to scale it would help me visualize how it is used.)
Vince
vrs wrote...
> I assume we screw the plate into place in the TU56 using the standoffs,
> and
> it has holes in it for the capacitor clamp? Or does it bolt directly
the
TU56, with the
clamp on standoffs?
the plate jpg is located at www.ezwind.net/jwest
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10 comments
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participants (6)
-
ard＠p850ug1.demon.co.uk -
eric＠brouhaha.com -
ethan.dicks＠gmail.com -
jwest＠classiccmp.org -
vrs＠msn.com -
william.layer＠comcast.net