sci.electronics.repair@googlegroups.com

Today's topics:

* Fuse or fusible resistor? - 3 messages, 3 authors
http://groups.google.com/group/sci.electronics.repair/t/2017b4927dae47ef?hl=en
* oops! coffee into the top of TV! - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/927853c231d2a8d2?hl=en

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TOPIC: Fuse or fusible resistor?
http://groups.google.com/group/sci.electronics.repair/t/2017b4927dae47ef?hl=en
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== 1 of 3 ==
Date: Sun, Jun 27 2010 12:08 pm
From: Jamie

Tim Williams wrote:

> "DaveC" <invalid@invalid.net> wrote in message news:0001HW.C84C25A9011554E5B01AD9AF@news.eternal-september.org...
>
>>Used in the battery (-) lead of a handheld scope. Schematics unpublished.
>>
>>Physically similar to a 1/4 W resistor, color light green. Marked "IE7A" or
>>"1E7A".
>
>
> Obviously, it's 10,000,000 amperes ;^)
>
> Tim
>
good one :)

== 2 of 3 ==
Date: Sun, Jun 27 2010 2:14 pm
From: James Sweet

>
> I take it , that its blown and I also take it that its not charred (fusible
> R don't char or even discolour AFAIK)
> Desolder it and scrape an axial line along its length . Then DVM resistance
> check from either end. If a fusible resistor then maximum R read is what its
> value was near enough.
> FR breaks are usually to one end, normal R usually in the middle.
> Although green is often axial inductor.
>
> --
>

They won't catch fire but I have seen them char slightly. It's also
common for them to crack or blow out a small chip of ceramic if
something shorts and exposes them directly to the line voltage.

== 3 of 3 ==
Date: Sun, Jun 27 2010 5:52 pm
From: fly on the wall

On Sun, 27 Jun 2010 00:27:45 -0700, DaveC <invalid@invalid.net> wrote:

>> I take it , that its blown and I also take it that its not charred (fusible
>> R don't char or even discolour AFAIK)
>
>No, I don't have one. I threw it out with the old battery. :-(
>Someone on-line volunteered to describe the one from his scope.
>I'll not ask him to do a post-mortem on a working fuse. ;-)

Surely (s)he can MEASURE the one (s)he has?

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TOPIC: oops! coffee into the top of TV!
http://groups.google.com/group/sci.electronics.repair/t/927853c231d2a8d2?hl=en
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== 1 of 1 ==
Date: Sun, Jun 27 2010 3:12 pm
From: Robert Macy

Did a bad thing to our little portableTV, a Funai, Model FT1371

EVENTS: Set coffee cup on top of TV, jostled the TV's table, liquid
went down through the holes on top, and voila! Screen shrunk, went
black - However, I quickly unplugged just as TV was going black.

DIAGNOSIS: Took apart case to find liquid had run onto the HV
connection, ran down HV cable to where cable was lying against the PCB
on back end of tube. At that location, suspect arc over to
electronics [Electronics was a bare solder tab sticking out with bare
copper wire going to a winding] and what appears as a 1/16 inch
discoloration on side of HV cable. Possibly always touching there and
that was dirt aging, or from an arc caused by the liquid.

ACTIONS: Cleaned everything up, dried off, reassembled. TV came on!
Lit up! Talk about lucky. But...colors went all wonky. At first
everything was all red [must not have been completely dry]. Let run a
couple of hours to dry completely, Colors shifted, but now
predominantly green.

OBSERVATIONS: White appears to contain excessive green. Good news is
that pure red is pure red. pure blue is pure blue. Black and White
programs are green and black, not black and white.

For what it's worth, I think I've seen this type of color once on a
similar inexpensive TV caused by some cheap pots near the CRT. Those
little plastic disk thingies with a metal wiper. All the structure's
are open to the atmosphere and not sealed at all. Simply, ajusting the
color [wiggling the wipers] returned color to original settings,
brought the color back that time.

QUESTIONS:
1) Any schematic for a Funai FT1371 ?
2) Anybody know what got zapped on the top tab of that PCB?
3) Assuming each video color channel is still capable, what adjustment
to bring back color balance?

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