At Fixya.com, our trusted experts are meticulously vetted and possess extensive experience in their respective fields. Backed by a community of knowledgeable professionals, our platform ensures that the solutions provided are thoroughly researched and validated.
Panasonic nn-sd670s shuts off after a few seconds.. The fuse is good. The transformer , diode, and capacitor does not look like a typical one such as the ones shown on the Internet .
The thermo switch is continuos, the fuse is good. The magnetron is continuous at 0.7 ohm. There's no continuity to the housing for the magnetron or the thermoswitch. Two door switches are only continuous when pressed. The third is continuous when not pressed( normally closed) it's the opposite of the other two. There's four small capacitors, two are brown and two are green. No single large one. There's two diodes the appear to be in series. The relay is soldered to the front panel circuit board. Can I unplug the wire to the inverter circuit board to test the relay that way? The conventional transformer , capacitor , diode layout does not seem to apply here. Everything looks different. What would cause it to turn off in seconds?
Re: Panasonic nn-sd670s shuts off after a few seconds.....
The on board relay may be defective. Also, this model is based on a switch mode power supply, commonly marketed as inverter microwave. But should be rather called an intensity modulator since what is does is pulse width modulation. An inverter would be DC to AC, without PWM
To test capacitors the best way is to leave them in the circuit and probe with a scope on each one for any ripple voltage. 1% to 4% ripple could be normal. Higher ripple likely indicates increased ESR from original specs. A meter on AC settings is enough only to measure 60Hz ripple. Most capacitors in circuit filters much higher frequencies, like 50KHz, 100KHz, 500Khz, 1MHz, 100MHz, 1GHz...To test capacitors the best way is to leave them in the circuit and probe with a scope on each one for any ripple voltage. 1% to 4% ripple could be normal. Higher ripple likely indicates increased ESR from original specs. A meter on AC settings is enough only to measure 60Hz ripple. Most capacitors in circuit filters much higher frequencies, like 50KHz, 100KHz, 500Khz, 1MHz, 100MHz, 1GHz...
You can't post conmments that contain an email address.
Accidentally posted the wrong web address for the inverter test procedure. It is:http://educypedia.karadimov.info/library...Accidentally posted the wrong web address for the inverter test procedure. It is: http://educypedia.karadimov.info/library/Inverter.pdf
You can't post conmments that contain an email address.
- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
It sounds like you were sold somebody else's problem, it could be a bad magnetron, cracked high voltage diode, and a shorted high voltage capacitor to name a few. I recommend a professional if you feel it is worth getting checked.
A wild guess: the scraping noise was a motor bearing seizing up (fan or turntable). A thermal cutout blew when something overheated. This would have taken several minutes to happen.
Alternate, and more likely explanation: the scraping noise was actually high-voltage arcing in a failed component, most probably the voltage doubler capacitor. This would blow the fuse. Replace both the capacitor and diode; the diode was probably overloaded and could fail at any time if it hasn't already. At $5-$10, it's cheap insurance against having to fix the thing twice.
When you say "Everything works as set" do you mean the microwave appears to function properly, but then doesn't heat?
If the magnetron is new, then the magnetron must not be receiving the required high voltage (2000V or more) from the HV circuit. Make sure you've got 120V to the PRIMARY (don't attempt to measure secondary voltage of the HV transformer without special equipment) of the HV transformer. After that check the HV capacitor and diodes. If these components test OK, then either your HV transformer is bad or your new magnetron is faulty. My experience is that the problem is usually in control circuitry, preventing 120V to the HV transformer, or opens/shorts in the HV components (diodes and capacitors).
Be very careful! Standard microwaves have 2100volt capacitors and commercial ones 4000 volt capacitors.
*Decharge your capacitor(s) before doing diagnostics*.
You are now testing the high voltage side (as it works on convection). The main components are a transformer, a capacitor, a diode and a magnetron (havent seen a triac in a panasonic residential). If you have a proper meter that can test uf, decharge the capacitor, then test the capacitor, if it reads 0, you need a new capacitor (10$ used typically, 14$ new from ebay). To test the magnetron, decharge the capacitor first, remove the spade connections, test each leg to the frame of the microwave... if it shows measurable resistance, the magnetron is bad. The transformer is not something you test as I personally dont have a 4000 volt meter. If the diode, the magnetron and capacitor are okay, then the transformer is bad. To eliminate any other function, disconnect the low voltage to the transformer run a micropower cycle and check the fuse.
Hope that helps. My first instinct is the capacitor.
first off does your unit have the word inverter writen on it if it does it could be a failed magntron or the invertor pcb approx repair between £70-150, if it does not then it could be the capacitor or the diode or the hv fuse or the transformer this would be a repair under £90 sorry i cant be closer in price it would need someone to have the right testing tools
Alot of the Panasonic models had the Transformer and Capacitor and Diode built into the power board situated bottom right as you look at the appliance.
Dont know of a way to actually discharge this arrangement.
High voltage parts are suspect. Need to put a voltmeter on the
input (primary) side to the high-voltage transformer (big heavy iron
thing in there) Should be getting 120Vac when it goes to cook
cycle. Don't touch the other (high voltage) side of this
transformer. If the power is there, you are looking at replacing
either the magnatron or the high-voltage capacitor and diode. Its
affordable if you do it yourself - buy the part on EBAY - lookup
"universal magnatron"
Hope ya fix it!
×