Microwave repair...

[Jan Panteltje]

I wrote

All RF via spectrum analyzers with RTL-SDR sticks, up to 1.6 GHz
https://www.ebay.com/itm/185946399375
https://panteltje.nl/panteltje/xpsa/index.html
old version, new one has more features and FM stereo
https://panteltje.nl/pub/xpsa-0.7.gif
and a downconverter for it for 2.4 GHz
https://panteltje.nl/pub/2.4_GHz_to_1.5_GHz_down_converter_closeup_IMG_4660.JPG

PS
I forgot, l also have several down converters from 10.7 to 12.75 GHz that work in part of the range with the RTL_SDR sticks
universal LNBs:
https://en.m.wikipedia.org/wiki/Low-noise_block_downconverter
Very good for weak signals, low noise figure, very sensitive

Build a 300 MHz analog scope in the early seventies, donated it...

 

[Fred Bloggs]

On Monday, June 19, 2023 at 12:53:21 AM UTC-4, Jan Panteltje wrote:

On a sunny day (Sun, 18 Jun 2023 08:54:44 -0700 (PDT)) it happened Fred Bloggs
bloggs.fred...@gmail.com> wrote in
214b80e8-c23b-45ac...@googlegroups.com>:
On Sunday, June 18, 2023 at 11:25:06 AM UTC-4, John Larkin wrote:
On Sat, 17 Jun 2023 22:42:32 -0700 (PDT), Phil Allison
palli...@gmail.com> wrote:

Tricky Ricky wrote:
--------------------------
My microwave stopped working last night.
Looks like it\'s the fuse.
I can barely make out 15A on the metal cap, but no indication of fast > >or slow blow.
The case is ceramic.


** You\'ll need an ohm meter test to tell if a ceramic case fuse is blown=
.
Any 15A ceramic of the correct size will work, but best find a HRC ( hi> >gh rupture current) type.

Any ideas?


...... Phil
A DVM (with thermocouple input) is a fundamental home appliance. As is
a bench power supply, a Dremel, some test leads, and a glue gun.

I\'ve considered having a cheap LCD oscilloscope around, but it would
be rarely or never used at home.

Microwave leakage detectors have REALLY come down in price- as in 10% the p> >rice from 30 some odd years ago.
https://www.amazon.com/s?k=microwave+oven+tester&crid=1563A4HS6W6JI&sprefix=microwave+oven+tester%2Caps%2C107&ref=nb_sb_noss_1
More universal is this:
https://www.ebay.com/itm/374555008463?
it has a pot to set sensitivity
detects any RF, beeps if you use a microwave from several meters away.
I calibrate it by holding it next to a Raspberry Pi and then turning the pot so it just beeps.

The American stuff is calibrated and NIST traceable, and people doing the work commercially are required to keep records of testing and reading. Many times the leakage is so small there is no reading on the calibrated scale, so they used to have a nominal x50 gain momentary button to cause a reading deflection as a reality check. It\'s real easy to blow out the front end of these meters, so better to walk them in from a distance.

Any RF will then trigger it.

Guy with celphone walking past the house makes it beep too..
Better turn your WiFi off (I do not use WiFi, security is broken)!
Also have a normal microwave leakage detector with small analog meter, it never shows anything on the microwave oven.

Only scope I have is the old Trio analog 10 MHz one... from 1979 or so, very portable, visible here:
https://panteltje.nl/pub/h501s_drone_remote_power_test_ground_control_1_IMG_6276.JPG
the frog is thinking
An other essential tool on that table:
voltage sensing screwdriver
https://www.tinytronics.nl/shop/en/tools-and-mounting/tools/screwdrivers/screwdriver-set-with-voltage-detector-3-pieces

All RF via spectrum analyzers with RTL-SDR sticks, up to 1.6 GHz
https://www.ebay.com/itm/185946399375
https://panteltje.nl/panteltje/xpsa/index.html
old version, new one has more features and FM stereo
https://panteltje.nl/pub/xpsa-0.7.gif
and a downconverter for it for 2.4 GHz
https://panteltje.nl/pub/2.4_GHz_to_1.5_GHz_down_converter_closeup_IMG_4660.JPG

So, bacics tools : soldering iron, .1 inch holes perfoboard (no peeseebees), brain,
and understanding.
https://panteltje.nl/panteltje/raspberry_pi_dvb-s_transmitter/
and programming experience in C and asm

But having huge femto second scopes in your workshop does of course impress customers...
That has always been the case

To test a f*cking fuse use a battery and lightbulb (Edison type) or LED with resistor if you wannabee modern.
else your tongue!

It is all simple, will be I my book: \'The Fart of Electronics\' provided I will ever write it.

Wonder, maybe I should, but then again after the nukes fall it will be back to spark transmiters
and what\'s that detector ?
https://earlyradiohistory.us/1917de.htm

OK, smoke signals then !

beep AI I am beep
hehe

 

[legg]

On Sun, 18 Jun 2023 22:49:15 +0100, Martin Brown
<\'\'\'newspam\'\'\'@nonad.co.uk> wrote:

On 17/06/2023 23:07, Ricky wrote:
My microwave stopped working last night. Looks like it\'s the fuse.
I can barely make out 15A on the metal cap, but no indication of fast
or slow blow. The case is ceramic. Any ideas?

Such protective fuses seldom blow without a very good reason.
Usually that the magnetron PSU has failed in some interesting way.

I had one fail that way and repaired under warrantee.

Replacing the fuse may only result in blowing it again immediately.

Standard UL single fault abnormals allows replacing fuse once.

RL

 

[Ralph Mowery]

In article <bvp19ilv7b27kdquemetuhansas1s6vkjr@4ax.com>,
legg@nospam.magma.ca says...

Such protective fuses seldom blow without a very good reason.
Usually that the magnetron PSU has failed in some interesting way.

I had one fail that way and repaired under warrantee.

Replacing the fuse may only result in blowing it again immediately.

Standard UL single fault abnormals allows replacing fuse once.

Sometimes a fuse may blow because it is old so to speak. I had an
amplifier that ran on 12 volts DC. About every 2 months the fuse would
open up. Nothing wrong with the amp. The fuse was rated for 20 amps
and the amp draw was 15 amps. The fuse and holder would get warm and
looing in the glass fuse it looked like the fuse just sagged out.

Where I worked sometimes the circuit breakers on equipment would trip.
If a quick check with an ohmeter did not show a problem it was
recommended we reset the breaker. Often that was all it took. This is
on 480 volt 3 phase equipment that could be from 5 amps to 200 amps.