REPAIRING AND NOT THROWING AWAY

REPAIRING AND NOT THROWING AWAY

Richtige Fernseher haben Röhren!

Richtige Fernseher haben Röhren!

In Brief: On this site you will find pictures and technical information about Service Modes, Circuit Diagrams, Firmware Update procedure, Disassemble procedure, Universal remote control set-up codes, Troubleshooting and more....

If you go into the profession, you will obtain or have access to a variety of tech tips databases HERE IT IS Master Electronics Repair !.

These are an excellent investment where the saying: 'time-is-money' rules. However, to learn, you need to develop a general troubleshooting approach - a logical, methodical, method of narrowing down the problem. A tech tip database might suggest: 'Replace C536' for a particular symptom. This is good advice for a specific problem on one model. However, what you really want to understand is why C536 was the cause and how to pinpoint the culprit in general even if you don't have a service manual or schematic and your tech tip database doesn't have an entry for your sick TV or VCR.

While schematics are nice, you won't always have them or be able to justify the purchase for a one-of repair. Therefore, in many cases, some reverse engineering will be necessary. The time will be well spent since even if you don't see another instance of the same model in your entire lifetime, you will have learned something in the process that can be applied to other equipment problems.
As always, when you get stuck, checking out a tech-tips database may quickly identify your problem and solution.In that case, you can greatly simplify your troubleshooting or at least confirm a diagnosis before ordering parts.

Happy repairing!
Today, the West is headed for the abyss. For the ultimate fate of our disposable society is for that society itself to be disposed of. And this will happen sooner, rather than later.

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..............The bitterness of poor quality is remembered long after the sweetness of todays funny gadgets low price has faded from memory........ . . . . . .....
Don't forget the past, the end of the world is upon us! Pretty soon it will all turn to dust!

©2010, 2011, 2012, 2013, 2014 Frank Sharp - You do not have permission to copy photos and words from this blog, and any content may be never used it for auctions or commercial purposes, however feel free to post anything you see here with a courtesy link back, btw a link to the original post here , is mandatory.
All posts are presented here for informative, historical and educative purposes as applicable within fair use. NOTHING HERE IS FOR SALE !

Wednesday 10 April 2019

HOW TO TEST A MICROWAVE OVEN MAGNETRON

How to test a Microwave oven Magnetron

Magnetron Test for Opens, shorts or Insufficient Power
Unplug the unit
Discharge all the H.V Capacitors.
Disconnect all the leads (connectors) from the magnetron terminals.
Step 1
Using an Ohm meter on its lowest resistance scale, measure the
resistance from one magnetron terminal to the other in either direction as shown on the illustration.
Meter should read less than 1Ω indicating that the filament is good. If Filament checks good, proceed to Step 2
Step 2
Using an Ohm meter on its highest resistance scale, measure the resistance from one of the magnetron terminals to the metal casing of the magnetron as shown on the illustration on the left.
Meter should read infinity (open circuit) regardless of meter polarity.
If the meter indicates a short (Less than 1 Ω), the magnetron is defective.
The following temperature test will indicate if a magnetron is weak. Make sure unit is plugged in.
1. Fill a beaker or cup with EXACTLY 8 oz (1 Cup) tap water.
2. Record the temperature of the water (Should be approx. 70o F)
3. Place it in the center of the microwave and heat it for the time specified*.
4. Water should be boiling. Record the temperature again.
5. Temperature should rise approximately 142o F (Go to Step 6 only if temperature rise is considerably lower than 142o F otherwise all magnetrons are functioning properly)
6. To test for the weak magnetron, connect one magnetron at a time and repeat Steps 1-4.
a. For ovens that contain 2 magnetrons (NE1257R, NE1258R, NE1757R, NE2157R), the temperature rise should be approximately 70o F per magnetron.
b.For ovens that contain 4 magnetrons (NE2180, NE3280), the temperature rise should be approximately 35o F per magnetron.
Field Expedient Power Determination Tests:
All times calculated using water starting at 70°F {21°C} brought to 212°F {100°C}.
Times given below should serve as the benchmark.
MODEL AMOUNT OF
WATER: VESSEL: TIME:
NE-1257/8 1 CUP PYREX MEASURE 2:15
NE-1757 1 CUP PYREX MEASURE 1:35
NE-2157 1 CUP PYREX MEASURE 0:54
NE-2180 1 CUP PYREX MEASURE 0:54
NE-3280 1 CUP PYREX MEASURE 0:40

Bose Solo 5 – Disassembling procedure
PCB Cover Removal
Remove the 6 screws indicated in Figure. Lift off the PCB Cover
Main PCB Removal
Disconnect the bluetooth antenna connector as indicated from the main PCB.
Note: Use care when removing the antenna connector as it is fragile.
Using a spudger, lift up the PCB and then pull it forward so the rear connectors clear the enclosure openings.
If needed, push the USB port gently with the spudger to help remove the main PCB.
Once the PCB is out from the enclosure, you will notice the transducer harness is at tached to the PCB.
Detach the transducer cable from the main PCB.
Note: Use a spudger or screw driver to re lease the locking tab from the transducer cable.
Metal Grille Removal
On the bottom of the unit, remove the two screws securing the grille as indicated in  Figure.
Then using a spudger, push the grille at the edge to move the metal grille forward from enclosure. Repeat this process for both side of the grille. This will create some space for your fingers later.
Turn the unit over. Grasp the grille by the sides and pull forward to release the grille edge from the enclosure.
Figures showing the locations for the grille guides from left, center and right. Work the grille out of the enclosure using care not to bend the grille.
Note: When installing the metal grille, make sure the grille is inserted in the grille guides as indicated in figures. Ensure this is done properly to ensure proper grille alignment.
Transducer removal
Then on the front of the unit, remove the eight screws securing the 2 transducers as indicated in Figure.
As figure shows the transducer harness goes through the enclosure. To remove the driver, detach the driver from the harness. On the driver, peel off the foam attached to the cable harness to reveal the connector.
Remove the wires from the drivers.
Note: If you confirmed the transducer is defective. You may skip this steps by cutting the cables from the transducer.
During the transducer assembly, ensure that the foam wires side are facing the square opening to the enclosure.
Note: This step ensure enough space for the harness to move into the enclosure without damaging it.
Posted By: FRANK at 05:17
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