sci.electronics.repair@googlegroups.com

Today's topics:

* Microwave advice - 3 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/cf0cdf1a15cc7e64?hl=en
* 60/40 vs. 63/37 Solder - 4 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/4620260930cd06a7?hl=en
* Zenith 25CC25 horizontal sweep problem - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/f0f84fb8db596265?hl=en
* Weird telephone problem - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/5b67728e19c05524?hl=en
* whoesale lebron james nba jersey - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/41a73c0e9539e0f3?hl=en

==============================================================================
TOPIC: Microwave advice
http://groups.google.com/group/sci.electronics.repair/t/cf0cdf1a15cc7e64?hl=en
==============================================================================

== 1 of 3 ==
Date: Sun, Jul 18 2010 4:34 pm
From: mike

Mr. Land wrote:
> OK, I see there is a long history of microwave over repair questions.
> But I don't seem to see a thread that has my question:
>
> So I have an older GE JVM1190 over-the-stove microwave unit.
>
> Symptom is no heat.
>
> When powered up and programmed to cook, the unit makes the expected
> humming noise (the same it's always made) but a cup of water in the
> chamber will not heat up.
>
> I've studied the microwave FAQ repeatedly and I believe I understand
> the dangers.
>
> I constructed a long wooden-stick-based discharger for the HV cap,
> discharged it (didn't get any spark at all), then ensured there was no
> residual voltage on either of its terminals. Then I shorted the
> terminals.
>
> First I "tested" the magnetron: infinite resistance from either
> cathode connection pin to ground, very low resistance between the two
> pins themselves. Seems OK.
>
> Then I tested the HV diode by placing it series with a 390 ohm
> resistor and applying 15 VDC, and meauring the voltage drop across the
> device. -15V negative biased, about 10 VDC forward biased...this
> seemed to be within range.
>
> Finally I tested the HV cap. It reads infinite resistance to the
> chassis from either terminal. Between the terminals my capacitance
> meters reads around 0.86 uF... which seems to be correct.
>
> I've heard mention of a possibly bad HV fuse. AFAICT, this unit
> doesn't have one of those.
>
> So...the HV cap seems good, the mag seems good, the diode seems good,
> the unit seems to draw appropriate current when in cook mode,yet the
> over won't heat food.
>
> What am I missing???
>
> Could the magnetron still be "bad" despite the fact that it doesn't
> read shorted/open?
>
> Thanks.
I just fixed mine.
The push-on wire connection to the interlock switch had developed
some resistance, melted the wire and trashed the connector.
Had the same problem at the wire from the power cord to the main switch.
It hadn't failed...yet...

== 2 of 3 ==
Date: Sun, Jul 18 2010 10:54 pm
From: "Mr. Land"

I have new info.

Firstly, though THANK YOU ALL for taking the time to try to help. I
appreciate it.

So....I have replaced the magnetron in this before. AND, I read that
there seems to be a rash of
problems with these magnetrons.

But, the new info: my wife told me she'd heard the uWave emit this
"loud arcing noise" just before it
stopped heating food.

I couldn't find any evidence of arcing within the HV section itself,
however, when I removed the magnetron and
inspected the "antenna" (?) it looked as though it had been arcing:
there is a brass-colored conical tip that's flattened at the top
with a hole in it. That extends down towards the body about 1/2", then
there is a violet-colored band of some
material I can't identify...it appears to be some sort of insulating
material. Then under that is the RF braided gasket.

Well, where the purple insulating bushing and the copper tip
meet..there is a slight blackening and pitting...as
though arcing had occurred part of the way around that seam.

Does it make sense that the magnetron would arc there?

Ordering a new one tomorrow...

Thanks!

== 3 of 3 ==
Date: Sun, Jul 18 2010 11:38 pm
From: "Mr. Land"

On Jul 16, 7:04 pm, Cydrome Leader <prese...@MUNGEpanix.com> wrote:
> Mr. Land <grafton...@yahoo.com> wrote:
> > OK, I see there is a long history of microwave over repair questions.
> > But I don't seem to see a thread that has my question:
>
> > So I have an older GE JVM1190 over-the-stove microwave unit.
>
> > Symptom is no heat.
>
> > When powered up and programmed to cook, the unit makes the expected
> > humming noise (the same it's always made) but a cup of water in the
> > chamber will not heat up.
>
> > I've studied the microwave FAQ repeatedly and I believe I understand
> > the dangers.
>
> > I constructed a long wooden-stick-based discharger for the HV cap,
> > discharged it (didn't get any spark at all), then ensured there was no
> > residual voltage on either of its terminals.  Then I shorted the
> > terminals.
>
> > First I "tested" the magnetron: infinite resistance from either
> > cathode connection pin to ground, very low resistance between the two
> > pins themselves.  Seems OK.
>
> > Then I tested the HV diode by placing it series with a 390 ohm
> > resistor and applying 15 VDC, and meauring the voltage drop across the
> > device.  -15V negative biased, about 10 VDC forward biased...this
> > seemed to be within range.
>
> > Finally I tested the HV cap.  It reads infinite resistance to the
> > chassis from either terminal.  Between the terminals my capacitance
> > meters reads around 0.86 uF... which seems to be correct.
>
> > I've heard mention of a possibly bad HV fuse.  AFAICT, this unit
> > doesn't have one of those.
>
> > So...the HV cap seems good, the mag seems good, the diode seems good,
> > the unit seems to draw appropriate current when in cook mode,yet the
> > over won't heat food.
>
> > What am I missing???
>
> > Could the magnetron still be "bad" despite the fact that it doesn't
> > read shorted/open?
>
> > Thanks.
>
> Is the transformer secondary good? check its resistance from the HV
> terminal to the chassis. Open = bad.
>

Yep, all resistances among transformer wires correspond to those shown
in the
block diagram enclosed in the unit.

> Is that microwave old enough to use a reed relay for defrost mode?
>

I don't believe so.

> Do you have a way to measure the HV from a microwave oven safely?- Hide quoted text -
>

I have a TV HV probe, but that's not safe...to use it with neg voltage
I'd have to reverse it, but then
the working end wouldn't have anywhere near enough HV insulation/
standoff...it'd be just an alligator
clip...no thanks! %^)

> - Show quoted text -

==============================================================================
TOPIC: 60/40 vs. 63/37 Solder
http://groups.google.com/group/sci.electronics.repair/t/4620260930cd06a7?hl=en
==============================================================================

== 1 of 4 ==
Date: Sun, Jul 18 2010 4:47 pm
From: Phil Hobbs

William Sommerwerck wrote:
>>> Correct. The original writer was probably confused by the
>>> fact that the materials ceramic ICs are made of can contain
>>> radioactive materials that can cause errors.
>
>> No, the alphas from lead are a real problem. Ten years ago, there were
>> folks going round to churches with lead roofs, offering them a new lead
>> roof in exchange for their old--and now low-alpha--lead ones.
>
> But where is the lead /within/ ICs? (The wires are bonded, not soldered.)
> Alpha particles have poor penetrating power.
>
>

Only a problem with flip-chip (C4) bonding. At one point I worked in
the packaging research group at IBM Yorktown lab (no, I'm not a
packaging guy--it's a long story).

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net

== 2 of 4 ==
Date: Sun, Jul 18 2010 5:13 pm
From: "krw@att.bizzzzzzzzzzzz"

On Sun, 18 Jul 2010 19:47:15 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>William Sommerwerck wrote:
>>>> Correct. The original writer was probably confused by the
>>>> fact that the materials ceramic ICs are made of can contain
>>>> radioactive materials that can cause errors.
>>
>>> No, the alphas from lead are a real problem. Ten years ago, there were
>>> folks going round to churches with lead roofs, offering them a new lead
>>> roof in exchange for their old--and now low-alpha--lead ones.
>>
>> But where is the lead /within/ ICs? (The wires are bonded, not soldered.)
>> Alpha particles have poor penetrating power.
>>
>>
>
>Only a problem with flip-chip (C4) bonding. At one point I worked in
>the packaging research group at IBM Yorktown lab (no, I'm not a
>packaging guy--it's a long story).

The C4 balls were lead-indium, IIRC.

== 3 of 4 ==
Date: Sun, Jul 18 2010 5:32 pm
From: Phil Hobbs

krw@att.bizzzzzzzzzzzz wrote:
> On Sun, 18 Jul 2010 19:47:15 -0400, Phil Hobbs
> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>
>> William Sommerwerck wrote:
>>>>> Correct. The original writer was probably confused by the
>>>>> fact that the materials ceramic ICs are made of can contain
>>>>> radioactive materials that can cause errors.
>>>> No, the alphas from lead are a real problem. Ten years ago, there were
>>>> folks going round to churches with lead roofs, offering them a new lead
>>>> roof in exchange for their old--and now low-alpha--lead ones.
>>> But where is the lead /within/ ICs? (The wires are bonded, not soldered.)
>>> Alpha particles have poor penetrating power.
>>>
>>>
>> Only a problem with flip-chip (C4) bonding. At one point I worked in
>> the packaging research group at IBM Yorktown lab (no, I'm not a
>> packaging guy--it's a long story).
>
> The C4 balls were lead-indium, IIRC.

Lead-tin eutectic in my era (1987-2008), followed by gold-tin currently,
IIRC.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058
hobbs at electrooptical dot net
http://electrooptical.net

== 4 of 4 ==
Date: Sun, Jul 18 2010 5:43 pm
From: "krw@att.bizzzzzzzzzzzz"

On Sun, 18 Jul 2010 20:32:22 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

>krw@att.bizzzzzzzzzzzz wrote:
>> On Sun, 18 Jul 2010 19:47:15 -0400, Phil Hobbs
>> <pcdhSpamMeSenseless@electrooptical.net> wrote:
>>
>>> William Sommerwerck wrote:
>>>>>> Correct. The original writer was probably confused by the
>>>>>> fact that the materials ceramic ICs are made of can contain
>>>>>> radioactive materials that can cause errors.
>>>>> No, the alphas from lead are a real problem. Ten years ago, there were
>>>>> folks going round to churches with lead roofs, offering them a new lead
>>>>> roof in exchange for their old--and now low-alpha--lead ones.
>>>> But where is the lead /within/ ICs? (The wires are bonded, not soldered.)
>>>> Alpha particles have poor penetrating power.
>>>>
>>>>
>>> Only a problem with flip-chip (C4) bonding. At one point I worked in
>>> the packaging research group at IBM Yorktown lab (no, I'm not a
>>> packaging guy--it's a long story).
>>
>> The C4 balls were lead-indium, IIRC.
>
>
>Lead-tin eutectic in my era (1987-2008), followed by gold-tin currently,
>IIRC.

The last time I dealt with any of this was in the mid '70s. Before TCMs, even
(LEMs). I'm pretty sure they were lead-indium, but there may have been tin in
there too. There was also an issue of polonium contamination causing
uncorrectable L1 errors, but that's a completely different issue.

==============================================================================
TOPIC: Zenith 25CC25 horizontal sweep problem
http://groups.google.com/group/sci.electronics.repair/t/f0f84fb8db596265?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Jul 18 2010 6:14 pm
From: Jim Adney

I'm trying to fix my '73 Zenith 25CC25. The problem is that the
horizontal sweep is not wide enough, so my picture is compressed
horizontally. I've lost about 10% of the width on each side. Other
than that, it's fine. I have both the Zenith service manual and the
Sam's for this set.

I've tried other hor osc tubes (6U10) and hor out tubes (20LF6) and
none of the ones I have (which should be good) worked any better (but
some were a bit worse. Not too surprising.)

This is a hybrid set, with 3 Zenith Duramodules. I have spares for
each module, but swapping in the appropriate spare made no difference.

I checked the B+ in the Horizontal stages, and it's fine, 274 V.

The Vertical also seems fine, but I just tried to check the 2nd anode
voltage, and got garbage readings from my HV probe. I'll take that
probe to work tomorrow and check it to see if I can nail down that
problem. It says I only have ~6800 V, which seems impossible. It's
supposed to be 26 kV, so if it was really that low I believe the
vertical sould be WAY overscanned, which it's not.

I've checked a few resistances that I can get to easily, and so far
they all seem good.

What I haven't done so far is try to get a scope in there to look at
the signal at each stage, so at this point I don't know where the
problem starts.

I'm hoping someone here will still be familiar with this old set and
can suggest some good places to look next.

thanks,

==============================================================================
TOPIC: Weird telephone problem
http://groups.google.com/group/sci.electronics.repair/t/5b67728e19c05524?hl=en
==============================================================================

== 1 of 1 ==
Date: Sun, Jul 18 2010 7:25 pm
From: Robert Macy

On Jul 18, 2:08 pm, nesesu <neil_sutcli...@telus.net> wrote:
> On Jul 18, 12:11 pm, David Nebenzahl <nob...@but.us.chickens> wrote:
>
>
>
>
>
> > On 7/18/2010 5:46 AM Andrew Rossmann spake thus:
>
> > > In article <4c40d4c0$0$2401$82264...@news.adtechcomputers.com>,
> > > nob...@but.us.chickens says...
>
> > >> (And by telephone I mean the kind God intended us to use, a regular old
> > >> land line, not those Dick Tracy cell-phone thingies.)
>
> > >> Client has a bunch of phones in their house. Starting a few days ago,
> > >> several of them don't work; pick them up, no dial tone. (Confirmed with
> > >> a good set which I used to test all the jacks.)
>
> > >> But get this: while I was there, at least one of the phones that doesn't
> > >> work (a wireless phone) rang on an incoming call. WTF?!?!? It rang, but
> > >> when picked up--nothing, dead. No dial tone trying to make a call.
>
> > >> Anyone familiar with the inner mysteries of the telephone system care to
> > >> try to 'splain this? How could a phone not work, but still ring on an
> > >> incoming call?
>
> > > You didn't mention this: What happens if you move a non-working phone to
> > > where a working phone is? Does it now work? If so, then it's a wiring
> > > issue. Otherwise, it's the phone itself.
>
> > Well, I didn't test that, but I did the reverse test which shows that
> > the problem is the wiring, not the phone: I took a working phone (a
> > regular, non-cordless phone) and plugged it in to a non-working phone
> > jack. It was dead, so the problem appears to me to be the wiring.
>
> > The phone that rang on an incoming call, by the way, was a cordless
> > (i.e., powered) phone, which tends to confirm the diagnosis someone else
> > here gave of a "DC open", a corroded connection that would pass enough
> > of the higher ring voltage to make the phone ring, but not enough to go
> > "off hook".
>
> > --
> > The fashion in killing has an insouciant, flirty style this spring,
> > with the flaunting of well-defined muscle, wrapped in flags.
>
> > - Comment from an article on Antiwar.com (http://antiwar.com)-Hide quoted text -
>
> > - Show quoted text -
>
> There is probably a break in L1 or L2 at a daisy chained jack. Down
> stream of the break, there is no DC path for loop current to trigger
> dial tone, BUT, since the ringer is AC, there can be a path back
> through the ringer of a phone bridging the break [effectively two
> phones in series] so the phone could ring, but not close the DC loop
> when taken off hook.
>
> Neil S.

EXCELLENT!

That would account for the electronic phone ringing very well,

Bet the old ATT 'dialer' phone has a weak ring, right?

==============================================================================
TOPIC: whoesale lebron james nba jersey
http://groups.google.com/group/sci.electronics.repair/t/41a73c0e9539e0f3?hl=en
==============================================================================

== 1 of 1 ==
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