Microwave timer/clock 4 digit 7-segmnt display is out. Timer

  • Thread starter Angelo Campanella
  • Start date
"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:d9jni61b48oscri3vr445hfsorrvnvfhva@4ax.com...
On Mon, 10 Jan 2011 14:17:07 -0500, "Angelo Campanella"
a.campanella@att.net> wrote:
I checked to output by measuring the time to boil an 8oz cup of water.
The tag say 700 watts of cooking power, and my timing result was
approximately that... close enough to say the magnetron was still OK.
Impressive.
What color is the display?
Red. LED seems plausible.
Red is LED. Orange could be vacuum fluorescent or LED. I'll be on
LED.
OK, it's gotta be LED.

Could I trouble you for the Amana model number so we don't have to
continue guessing.
Set recently but again, but here again:

Model: RR6W, P72110-4M
S/N: H56559799
1600 Watts
(I recently measured it as 1,480 watts when running empty.)
Mfg Date May, 1976.

I know you guys recommend that I replace it,
Please re-read the previous comments. Nobody suggested you replace
it. This isn't a newsgroup dedicated to appliance salesmen. If it
cooks well, it should be possible to fix it.
but I don't see anything I like.
What's the problem? Too many features? Short lifetimes? Bizarre
warranties? Lousy construction? All of these?
1- War stories of new microwaves, mostly of Pacific Rim manufacture,
failing after a few years of service.

My son bought me a new one a Christmas go, but it turned out to be
smaller and of Pacific Rim manufacture, so I gave it back to him to give to
somebody else. This Amana is still the war horse.

2- I like this size (over a cubic foot). I think I'd like another Amana... I
think Raytheon bought them out some years ago. The name is still around. I
looked up their web age, and several models are available . A cubic foot+
unit cost about $150 last year... It's in he back of my mind.

I think you might find it useful to learn how to cook.
I'm looking for a human replacement, but so far no luck.

To keep my weight down, I eat a lot of salads; they require no cooking.
I cook soups from scratch and spaghetti & pastas with the u-wave. I eat very
little meat, mainly chicken, since red meats are heavy and affect my blood
pressure. I eat most anything on special occasions only.

Think of it as
chemistry and not an art form. Microwave cooking is ok for many
things, but there's plenty of dishes that are best cooked over a
flame, on a grill, or in a real oven. Then there's barbecue.
Cooking, especially frying, sends all kinds of odors into the house
(3-bedroom ranch, closed tight in the winter) that odiferate for hours
later... I eat meats mainly when eating out with friends.

The other son gave me a Forman burger grille. I only used it once. It
really smelled up the house . The range hood was not really of much help.
The Forman grille is best used outdoors.

Back to my Amana RR6W, my only hope to get display functioning back is
to identify the failed component (driver chip?), or replace the entire panel
module... both of which seem highly unlikely. This news group is about the
place I can find to even have an intelligent discussion on the matter. What
is needed is an old-timer that remembers the 7 digit LED display technology
of the '70's and also know the Amana microwave oven use of them.

Getting that circuit board out in the clear to work on it seems to be
nigh impossible. It is in place behind and parallel to the numbers panel.
But its back side is shielded over 2/3 its area with the power supply and
its heat sink. Numbers are on the top end. The bottom end is not in a
connector slot, but rather it's stationary with power supply bus wires and
switching relay control wires soldered in place.

Ange
 
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:igh3nm$i55$1@news.eternal-september.org...

So what are some of the numbers on the chips inside and any numbers seen
on
the sides of the display/s ?
I managed to pry out 7-segment chip digit #2 chip for review.

It's a 19mm x 10mm 14 pin (3 pins not present) HP5082-7730 609 C.

The face is a transparent matte plastic surface that seem to have red solid
state material for each of the 7 segments over the interior material.

The back side, between pin rows, is pink transparent potting that covers a
PC board holding the 14 (really net 11) pins.

Ange
 
"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in message news:jm3qi65p1idgetb0ttd7l79uk4fo7nhb82@4ax.com...
That's just a regular old 0.3" seven-segment common-anode LED display,
like the old Monsanto MANxxx displays.

http://www.datasheetcatalog.org/datasheets2/31/319472_1.pdf
All well and good. But I need a typical driver circuit diagram to probe voltages. It could be something as simple as a dropping resistor that's opened up, or a local filter capacitor that is shorted... I need a pin voltage map to find which voltage is missing.

We've got an antique Amana Radarrange with similar red LED displays.

Here's a more modern equivalent that is pin-compatible:
http://www.kingbrightusa.com/images/catalog/SPEC/SA03-11EWA.pdf
(but more than 10x as bright at the same current)
The brightness is plenty good for kitchens,

(well, pin compatible on the segments, but it has a right-hand decimal
point rather than the rare left-hand on the microwave oven, so not
really 100% compatible...)
The decimal point is not used for microwave heating.

Ange
 
I recently measured it as 1480 watts when running empty.
Akkk! If you keep running it empty, you might damage the magnetron.

I'm reminded of the opening of "The Outer Tsimmes"...

"There is nothing wrong with your television. But if we keep f***ing with it
like this every week, pretty soon there will be."
 
On Tue, 11 Jan 2011 23:21:09 -0500, "Angelo Campanella" <a.campanella@att.net>
wrote:

"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in message news:jm3qi65p1idgetb0ttd7l79uk4fo7nhb82@4ax.com...
That's just a regular old 0.3" seven-segment common-anode LED display,
like the old Monsanto MANxxx displays.

http://www.datasheetcatalog.org/datasheets2/31/319472_1.pdf

All well and good. But I need a typical driver circuit diagram to probe voltages. It could be something as simple as a dropping resistor that's opened up, or a local filter capacitor that is shorted... I need a pin voltage map to find which voltage is missing.
If you look at this page:-
http://www.decodesystems.com/old-displays.html
There are two gifs from an HP appnote.
They shows suitable multiplexing circuits.
It is possible that your circuit has stopped multiplexing so only single
segments permanently on.
May be missing a clock signal.


--
Geo
 
Angelo Campanella <a.campanella@att.net> wrote in message
news:igj8v9$lgk$9@speranza.aioe.org...
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:igh3nm$i55$1@news.eternal-september.org...

So what are some of the numbers on the chips inside and any numbers seen
on
the sides of the display/s ?

I managed to pry out 7-segment chip digit #2 chip for review.

It's a 19mm x 10mm 14 pin (3 pins not present) HP5082-7730 609 C.

The face is a transparent matte plastic surface that seem to have red
solid
state material for each of the 7 segments over the interior material.

The back side, between pin rows, is pink transparent potting that covers
a
PC board holding the 14 (really net 11) pins.

Ange

Can you view the board enough to count the pins on each of the non-display
electronic chips?
 
"N_Cook" <diverse@tcp.co.uk> wrote in message
news:igmsb5$ifv$1@news.eternal-september.org...
Can you view the board enough to count the pins on each of the non-display
electronic chips?
Have to unscrew the bezel allen screws again. in a few days..

Ange
 
"Geo" <hw9j-s5hw@dea.spamcon.org> wrote in message
news:cfsti651b4s20lm4ge8tstl36nbnhfiocu@4ax.com...
If you look at this page:-
http://www.decodesystems.com/old-displays.html
Seems to be near what I have.

There are two gifs from an HP appnote.
They shows suitable multiplexing circuits.
It is possible that your circuit has stopped multiplexing so only single
segments permanently on.
May be missing a clock signal.
I'm an old discrete component and vacuum tube guy.

I presume that "strobe" means hat there is only one driver, the SN7447
which is the only segment feeder, that the digit switched on at the moment
by the strobe signal will take segment current and light up.

The current comes from the 7447, whatever of the 7 lines is to run to
make the number of the instant.

In my uwave, only E segment is lit and the E of all 4 digits are on all
the time. No other segments of all 4 digits ever light. Well, actually the
4 of digit 4 is lighting every time its turn comes in the countdown. Perhaps
that digit is more sensitive.

One thing for me to look at is the health of the seven 47 ohm resistors.

Another is to check the + voltage supply. Do I expect 5 volts or some
higher value? The two raw dc supplies are 10 or 20 volts (the filter
capacitors gave away their location.)

Ange
 

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