Digest for sci.electronics.repair@googlegroups.com - 10 updates in 4 topics

Frank Baron <frankbaron@example.com>: Dec 21 04:10PM

How do I decide if these five tires are holed too close to the sidewall?
http://i.cubeupload.com/qD9rZv.jpg
 
Yesterday, for practice in dismounting, patching, and remounting, I patched
these 5 tires above, which a friend and I had lying around.
http://i.cubeupload.com/gCNODb.jpg
 
For the purpose of this thread, we can ignore the tread wear since the
question is being asked about how to decide when a nail hole is too close
to the sidewall.
http://i.cubeupload.com/0X8NfQ.jpg
 
I guess the first question is *WHY* we can't patch next to the sidewall.
Is it that the patch won't hold? Why?
Is it that the patch will flex too much?
Or is it that the belts are damaged and they will break?
"pfjw@aol.com" <pfjw@aol.com>: Dec 21 08:21AM -0800

Horatio Alger/Norman Spruance/John Harmon/Frank Bacon is BAAAAAAAAACK.
 
Please do not dignify his drivel with a response.
 
Peter Wieck
Melrose Park, PA
Wade Garrett <wade@cooler.net>: Dec 21 11:38AM -0500

On 12/21/16 11:10 AM, Frank Baron wrote:
> Is it that the patch won't hold? Why?
> Is it that the patch will flex too much?
> Or is it that the belts are damaged and they will break?
 
Gotta' ask....what is your ongoing fascination with tire
dismounting/mounting/repairing ;-)
 
--
Make America great again? Hell, I'd be happy if you just made it America
again.
- @KelsowFarlander
Phil Allison <pallison49@gmail.com>: Dec 20 04:04PM -0800


> The clear plastic wrap around the transformer is also mostly melted.
 
** So it is a toroidal type ???
 
Should be easy enough to get one made that is near identical.
 
 
.... Phil
Bruce Esquibel <bje@ripco.com>: Dec 21 11:30AM


> Correct - 53VAC - I linked the clear schematic, while still looking at the
> blurry one.
 
Ok, if this is a "for yourself" repair, I'd do what someone else suggested
and use multiple transformers. At least one for the low current pair and
the oddball for the dual 53V side.
 
One suggestion, you can probably find dual 48V ones without too many
problems, those had to have been used by the telcos for charging their
batteries when everything was copper based.
 
I really think the 5V difference is going to make little change, probably
cut a couple watts off peak output but should be totally safe to use.
 
At least you can see if the rest of it still works and if it does, just
leave it like that while in search of something closer to the original one.
 
-bruce
bje@ripco.com
"pfjw@aol.com" <pfjw@aol.com>: Dec 21 04:32AM -0800

On Tuesday, December 20, 2016 at 7:04:33 PM UTC-5, Phil Allison wrote:
 
> ** So it is a toroidal type ???
 
> Should be easy enough to get one made that is near identical.
 
> .... Phil
 
Not a toroid. Remember, this is a Revox - never use one part when three-or-more will do better. There is a clear plastic clam shell over the windings but under the end bells. It is also a 'double C' core.
 
I am trying to avoid multiple transformers - the on/off switching scheme is complicated enough without introducing additional connections. But, if I must go that way eventually, I will.
 
Peter Wieck
Melrose Park, PA
Jon Elson <jmelson@wustl.edu>: Dec 20 04:01PM -0600

Stephen Wolstenholme wrote:
 
> wrote:
 
>>I do not know where to post this but there are plenty of smart forgiving
>>folks here.
Well, I had a crazy one some years back. One of the classic freezer on top,
refrigerator below, with a wide mullion between the doors, that held the
evaporator coils. The refrigerator started condensing water and dripping
all over the food below. I tore the mullion apart, and there was a
compartment that looked like a picnic cooler, just a bare styrofoam box,
with the coils and defrost heater inside. there was some ice there, but it
was clear the defrost heater was working, as there was no ice near it.
I took out the styrofoam, and the lower part weighed about 20 LBS!! I left
these out, and ended up putting them in a trash bag with a vacuum pump for
several hours a day to draw the water out. I'd weigh it every day, and when
it stopped getting lighter, I reinstalled it, but wrapped it in trash bag
material to try to keep the foam from getting waterlogged again. This de-
watering process took over a week. It did fix the problem.
 
Jon
etpm@whidbey.com: Dec 20 04:45PM -0800

On Tue, 20 Dec 2016 16:01:55 -0600, Jon Elson <jmelson@wustl.edu>
wrote:
 
>material to try to keep the foam from getting waterlogged again. This de-
>watering process took over a week. It did fix the problem.
 
>Jon
That styrofoam waterlogging is a problem with hot tub covers. The last
cover I replaced took two peope to lift it off of the tub when it was
replaced. Really one person could have done it except it was so big
AND heavy that it was really awkward. I paid extra for the new cover
becuase it has extra wrapping to slow down how fast the styrofoam
absorbs moisture. Your vacuum pump idea is a good one. I wonder how
long it would take to dehydrate a hot tub cover. Maybe wait 'till the
middle of winter and freeze dry it. Yeah, right.
Eric
"pfjw@aol.com" <pfjw@aol.com>: Dec 20 09:15AM -0800

On Tuesday, December 20, 2016 at 11:11:50 AM UTC-5, N_Cook wrote:
> 4 IRF740 and 4x RFPN06 and a 7812 complete the main active stuff, what
> would be most likely mechanical failure inside? DIP IC, transistor,
> diode, other?
 
Look wherever something heavy is attached to something light, and at some angle other than aligned to the drop force. Anywhere there is heat at such a connection, irrespective of the angle-of-force.
 
This will be something that bright light and a magnifying glass will reveal along with the usual 'wiggle-it-a-little". And, as you are not getting _any_ symptoms, I suspect more towards the input side of things.
 
Peter Wieck
Melrose Park, PA
N_Cook <diverse@tcp.co.uk>: Dec 20 06:26PM


> This will be something that bright light and a magnifying glass will reveal along with the usual 'wiggle-it-a-little". And, as you are not getting _any_ symptoms, I suspect more towards the input side of things.
 
> Peter Wieck
> Melrose Park, PA
 
error in title, renamed model.
First one of these things I've looked at, no SMD but lots of on-end "6
transitor radio" fashion minor comps.
First thing to try is cleaning and refitting the 2 TL494 as they're in
sprung sockets for some odd reason
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