Digest for sci.electronics.repair@googlegroups.com - 8 updates in 3 topics

9:46 AM Penedão
Jeff Liebermann <jeffl@cruzio.com>: Oct 24 05:34PM -0700


>> Thanks.
 
>-=-=-=-
 
>I've been misunderstood from the get-go.
 
No, you mis-stated the problem. Read your own posting and see how you
would answer your own question. You asked for a "cleaner" and
received several suitable replies.
 
>The rollers are fine. I don't need a restorer. I just want to keep from
>accelerating their hardening over time by using a cleaner that doesn't dry
>them out faster than heat and oxygen do.
 
You could make a fortune if you had a process for doing that.
 
Rubber rollers contain a well controlled percentage of some type of
oil. It's this oil that gives the rubber its flexibility which helps
prevent surface wear. As I vaguely recall and am too lazy to search
for, it's about 10-25% oil by weight. The way the oil is injected
into the rubber is with a solvent carrier. These are usually noxious
solvents such as toluene and xylene. The oil can be almost anything
that doesn't attack the rubber or interfere with the various rubber
additives. Here's a pitch line for soy oil in rubber:
<http://soynewuses.org/wp-content/uploads/44422_MOS_Rubber.pdf>
"Tests have shown that using soy oil in tires can potentially
increase tread life by 10 percent while reducing the use
of petroleum-based oil."
 
When rubber "dries out", it really means that it has lost most of the
surface oil mixed in with the rubber. Smearing some oil on the
surface won't replace the oil. What does work is a mix of oil and a
carrier (tolune or xylene) which expands the rubber sufficiently for
the oil to be absorbed. How much is absorbed will determine the life
of the rubber part. Too much and it might fall apart. Too little and
you're left with a rock hard surface. Using pure solvent, with no
oil, is a guaranteed failure because it expands the rubber, but does
not replace any of the missing oil.
 
Note that this has nothing to do with the vulcanization failure in
rubber, where the rubber de-vulcanizes, reverts back to "natural"
rubber, and turns into a sticky, gooey, tar-like mess.
 
Good luck.
 
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
M Philbrook <jamie_ka1lpa@charter.net>: Oct 24 09:48PM -0400

In article <0001HW.1DBC846A001D9BEA10BE433BF@news.eternal-
september.org>, not@home.cow says...
 
> What alternative cleaner do you use on printer rollers and such?
 
> I?ll take my answer off the air. (c:
 
> Thanks.
 
liter fluid..
 
Jamie
N_Cook <diverse@tcp.co.uk>: Oct 25 12:00PM +0100

On 25/10/2016 01:34, Jeff Liebermann wrote:
> rubber, where the rubber de-vulcanizes, reverts back to "natural"
> rubber, and turns into a sticky, gooey, tar-like mess.
 
> Good luck.
 
Do you happen to know what causes contangion in rubber ?
If one band fails by stretching or going gooey, then the others usually
are failing in the same way. I'm assuming they are not of the same batch
at manufacturing and then the same ageing failure but some gas or
biological vector moving about inside a casing
Michael Black <et472@ncf.ca>: Oct 24 02:04PM -0400

Jeff Liebermann <jeffl@cruzio.com>: Oct 24 12:16PM -0700

>Need help to find any information for replacement, as manufacturer,
>data sheet, possible replacements type, etc.
>Thanks
 
Yep. Junk ceramic filters are an all too common problem. I saw an
ICOM IC-M411 marine radio with an identical filter problem. It was
fixed under the warranty, so I didn't a chance to play with it.
<http://sv8ym.blogspot.co.uk/2010/07/mysterious-case-of-withering-filters.html>
I'm not sure what caused the problem but as I recall, it happened very
quickly after the initial OOB (out of box) experience. Everything was
fine for a few days, then nothing. Sound familiar?
 
The filter is extremely common and you should have no trouble finding
one:
<https://www.google.com/#q=M50FW+filter>
Maybe stock up? 20 pcs for $20:
<http://www.ebay.com/itm/200974082569>
 
 
--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
6dinopaoloREMOVE@gmail.com: Oct 25 08:51AM +0200

On Mon, 24 Oct 2016 12:16:58 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:
 
><https://www.google.com/#q=M50FW+filter>
>Maybe stock up? 20 pcs for $20:
><http://www.ebay.com/itm/200974082569>
 
 
Jeff,
while de soldering one of them, the case fall apart and find green
sign of oxidation inside, as described in the above link.
 
This is a sort of blind repair (no schematic and no RF equipment).
 
Is the LTM 450DW a correct replacement?
Dino
N_Cook <diverse@tcp.co.uk>: Oct 25 11:54AM +0100

On 24/10/2016 16:33, N_Cook wrote:
> hooking up an RF oscillator to test if failed FM receiver. Unfortunately
> not the silver migration, ohmic problem ,something else around an LA1186
> FM front end, all DC are correct by the schematic.
 
In my case it was failed 20 yearold solder at one of those large wire
1.5 turn air cored inductors, presumably from heatsinking of the
original PbSn soldering
DaveC <not@home.cow>: Oct 24 03:22PM -0700

On 24 Oct 2016, N_Cook sez:
 
> turn off ,then on, power at the wall , rather than on the m/c?
 
Turns out the instructions were incomplete.
 
Through trial and error I figured it out.
 
Thanks.
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