Digest for sci.electronics.repair@googlegroups.com - 7 updates in 4 topics

Mike S <mscir@yahoo.com>: Jul 22 08:56PM -0700

On 7/22/2019 7:07 AM, root wrote:
> because it has no output. At least that is how I figure it to
> work. With this arrangement, and a new video card, the system
> is working very well.
 
Your analysis makes sense, glad you solved it.
Stu jaxon <stankowalski02@gmail.com>: Jul 22 03:59PM -0700

On Sunday, July 21, 2019 at 9:21:18 AM UTC-4, John-Del wrote:
 
> > with the new tcon board installed, ON FB to ground both sides are .3-4m ohms. with lvds unplugged 400k one side other 300k ohms.. TV on testing pins closest to FB the highest was 1.4v - 0v..
 
> > Old Tcon board... .4 ohms both sides,.. lvds unplugged .3 ohms... TV on .2mv on FB TV lvds unplgged pins closest to FB 2v- .3 mv.. hope i covered everything...
 
> Standby till Monday. I have a donor set of boards for that model but it's for the version with a separate TCON and FRC, so I don't have the combo TCON that you do. Still, the voltages from the main should be the same on the LVDS harness. I'll put the boards together and get some voltage readings.
 
I found both fuses on the main boards are open f701,.. circled in yellow, the fuses are next to cn701 harness from the power supply. https://imgur.com/a/yf8cz7v
tabbypurr@gmail.com: Jul 22 03:01PM -0700

On Monday, 22 July 2019 11:01:31 UTC+1, Phil Allison wrote:
> tabbypurr wrote:
 
> > What you don't understand is that you're in your own world.
 
> ** What the lunatic Thornton Troll does not understand is that he is completely out of his fucking head.
 
that's one way to confirm what I said
plonk
etpm@whidbey.com: Jul 22 10:34AM -0700

On Mon, 22 Jul 2019 05:06:05 -0700 (PDT), "pfjw@aol.com"
 
>The chemistry in that battery had "flipped over" such that it was producing current opposite to the marked poles. Not uncommon with cheap batteries that often blow up even before being unwrapped.
 
>Peter Wieck
>Melrose Park, PA
I know the chemistry somehow reversed. What I would like is an
explanation of what happened in detail. How the chemistry reverses.
Eric
Fox's Mercantile <jdangus@att.net>: Jul 22 12:47PM -0500


> I know the chemistry somehow reversed. What I would like is an
> explanation of what happened in detail. How the chemistry reverses.
> Eric
 
Completely discharged batteries can be reverse charged.
So, imagine, a dead cell in series with others, there's your
reverse charging potential.
 
 
--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com
"pfjw@aol.com" <peterwieck33@gmail.com>: Jul 22 11:33AM -0700

> I know the chemistry somehow reversed. What I would like is an
> explanation of what happened in detail. How the chemistry reverses.
> Eric
 
OK:
 
Parts and pieces, simplified:
 
Zinc anode current collector.
Manganese Oxide Cathode.
Potassium Hydroxide Electrolyte/Anode
 
Chemical Reactions = power + heat.
External Heat will increase the completeness of the reaction.
When that heat is removed, there is an opportunity for the reaction to reverse.
When the expansion seal fails (the chemical reactions increase internal volume, and so will cause cheap batteries to leak), oxygen added to the system will react with the other chemicals and start that reverse reaction.
 
Notice that the reverse reaction is a very tiny fraction of the primary reaction, and needs a considerable and elaborate sequence-of-events to take place:
 
a) Over Reaction
b) Leak
c) Oxygen
 
Peter Wieck
Melrose Park, PA
John-Del <ohger1s@gmail.com>: Jul 22 01:03PM -0700

On Monday, July 22, 2019 at 1:47:53 PM UTC-4, Fox's Mercantile wrote:
> Jeff-1.0
> WA6FWi
> http:foxsmercantile.com
 
 
Yep. You see this a lot when people mix batteries in a device. Almost invariably, one will be die before the others and get reverse charged.
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