- Home


Air Conditioners | Dehumidifiers | Dishwashers | Disposals | Dryers | Freezers | Humidifiers | Ice Makers | Microwave Ovens | Ovens, Ranges, Stoves | Refrigerators | Trash Compactors | Washers | Water Filters

FAQs | Contact | Apprenticeship | Parts | Model Number Help | Newsletter | Beer
- > Do-It-Yourself Appliance Repair Help > The Kitchen Appliance Repair Forum > Panasonic Inverter Microwaves - Advanced or retrograde?

Find Appliance Parts & Diagrams Here
Enter a model number, part number, type of appliance, brand, or even a part description.

365-day return policy on all parts ordered through this site!


 Moderated by: BrntToast, RegUS_PatOff, appl.tech.29501 Search Our Sites for More Info! Page:  First Page Previous Page  1  2  3   
New Topic Reply Printer Friendly
Panasonic Inverter Microwaves - Advanced or retrograde?  Rating:  Rating
AuthorPost
 Posted: Thu Oct 22nd, 2009 09:27 pm
  PM Quote Reply
41st Post
iceman
Master Appliantologist


Joined: Wed Apr 6th, 2005
Location: Uzbekistan
Posts: 76
Flavorite Brew: Big Rock Traditional Ale
Status: 
Offline
un·re·pent·ant

(nr-pntnt)
adj.
Having or exhibiting no remorse.



____________________
iceman
Back To Top PM Quote Reply  

 Posted: Thu Oct 22nd, 2009 09:40 pm
  PM Quote Reply
42nd Post
RegUS_PatOff
Fellow, Academy of Sublime Masters of Appliantology


Joined: Sat Sep 24th, 2005
Location: Milwaukee, Wisconsin USA
Posts: 16509
Flavorite Brew: Indian Head. Black & White
Status: 
Offline
King Gillette: "Free Razor" (buy our replacement blades)

Free cell phone ...

Free lunch ...

etc ...



____________________
The new repair forums==> http://appliantology.org
Back To Top PM Quote Reply

 Posted: Sun Nov 8th, 2009 11:23 am
  PM Quote Reply
43rd Post
Konnan
Merit Apprentice Appliantologist
 

Joined: Wed Nov 4th, 2009
Location:  
Posts: 5
Flavorite Brew: iceman
Status: 
Offline
grindit wrote:
Hi Iceman-

Read your post with interest as I do have a countertop Panasonic Inverter Microwave Model NN-S760WA that I bought in late 2000.  It just died this week, so yes, it did last over 5 years.  It will turn on briefly but shut off after a 4-5 seconds, not enough to heat anything. 

I checked the interlock switches and they are OK, but that's about as far as I got.   It was a nice unit while it lasted.  Not knowing much about Inverter ovens, any diagnostic suggestions while I have the patient open prior to sending it to microwave heaven? 


Hi Master iceman,

God of the mighty Panasonic Inverter Microwave, could you help me ?

I have exactly the same problem as the guy I quoted above. Microwave will work for a few seconds at a time at most.

It was slightly arcing due to excess grease, because of the bad integrated hood fan design, grease manage to get inside the microwave electronics.

Managed to fix the arcing problem with a good cleaning, but obviously something is damaged.

The high voltage power diode looks to be burnt, due to blackened PCB in the area... I wonder why it still works for a few seconds on the other hand... could it be only a fan problem then the microwave enter in protection mode ?

Diode is UX-C2B made by SANKEN Electric, now discontinued part worth 30$ on eBay with no SANKEN Electric equivalence, but a local store can supply an equivalent from another brand for 5$.

Should I also look at the high voltage capacitor or somewhere else ?

Thanks alot Master iceman,

If anyone else wants to help me, I'm all ears.

Thanks !
Konnan

Last edited on Sun Nov 8th, 2009 11:25 am by Konnan

Back To Top PM Quote Reply  

 Posted: Sun Nov 8th, 2009 06:37 pm
  PM Quote Reply
44th Post
iceman
Master Appliantologist


Joined: Wed Apr 6th, 2005
Location: Uzbekistan
Posts: 76
Flavorite Brew: Big Rock Traditional Ale
Status: 
Offline
Hi Konnan,

To quote our erudite leader

"Never replace a part unless you have proof that the part is bad."

http://fixitnow.com/wp/2005/09/23/samurais-12-laws-of-appliance-repair/

Let us consider.  You have used a special tool to remove tamper proof fasteners to gain access to the POWER Printed circuit board of a device designed to emit MICROWAVES.  Presumably you read the prominent safety warnings on the unit as you did so.  Suppose that you did manage to replace enough parts to make it work.  Lets postulate some follow-on questions:

1) Was the arcing caused by grease or by the normal failure mode of this product?

2) How long will it work for before it fails again?

3) Are you comfortable being near this device while it is operating under your fresh repair?  How about your kids?

4) Could your repair result is a fire when you are not at home?

OK, let's assume that you have decided to disregard the cautions above and are prepared to assume full responsibility of the consequences of your repair or losses resulting therefrom.  Here are the logical steps the I would follow if I had decided not to just replace the unit.

1) Try to obtain a schematic of the power converter board. 

2) Failing that, write down all the part numbers of the power devices (FETs, Diodes, BJTs).  The really damaged ones might be illegible

3) Get the data sheets for the defective devices.

4) De-solder all power devices and test them.

5) Replace the defective ones.

Once again, I STRONGLY recommend that you dispose of this microwave and go get a new one.  That is what I did, and I am very satisfied with it.  This project has exponentially diminishing returns.

Oh, and don't forget the flip Panasonic the bird.

 



____________________
iceman
Back To Top PM Quote Reply

 Posted: Sun Nov 8th, 2009 07:34 pm
  PM Quote Reply
45th Post
Goosegog
Senior Apprentice Appliantologist


Joined: Thu May 31st, 2007
Location: British Columbia Canada
Posts: 18
Flavorite Brew: St Ambroise Apricot Wheat Ale
Status: 
Offline
Further to my post of April 21 2008 we have finally got fed up with a microwave that only operates for 23 seconds at 1/3 power. Because of the vent and trim kit issue I have purloined another Pana (NNT795S - CAN$220 at London Drugs) which seems to be the only one that fits. It's been there 3 days and still works, so it looks very promising.

Interestingly, it's almost impossible to fit the existing vent kit sheet metal to the new unit, as Pana has changed the security screws on the back from a "star" pattern to a "star-with-a-projecting-prong-in-the-middle" pattern, for which I do not have the proper tool. Vice-grips rule! It's only one screw, so I hope this will not invalidate the warranty.

Back To Top PM Quote Reply  

 Posted: Sun Nov 8th, 2009 08:05 pm
  PM Quote Reply
46th Post
Konnan
Merit Apprentice Appliantologist
 

Joined: Wed Nov 4th, 2009
Location:  
Posts: 5
Flavorite Brew: iceman
Status: 
Offline
iceman wrote:
1) Was the arcing caused by grease or by the normal failure mode of this product?

1) Try to obtain a schematic of the power converter board. 

Oh, and don't forget the flip Panasonic the bird.


Thank you for this nice reply, iceman, Master of the Panasonic !

Thank you for the link to the 12 laws... should have read that before hehe !

1) Well, removing grease removed arcing between power board and a ground screw when the microwave is working, but yes I guess it's just delaying its death a few more years...

1) Getting a schematic for an inverter power board from a discontinued Panasonic microwave ? Pretty much impossible, isn't it ?

You have many valid points, but these damn large microwaves with integrated hood fan vents are several hundred $$$ expensive... so I may want to try replace that 5$ diode... I will not play with the magnetron or waveguide, don't worry, be happy !

As you said, if that doesn't work, it will be lost time, lost money and a lost cause, so I need to further think about it. That diode is probably not the only damaged part.

Agreed on the "flip the bird" part... ;-)

Thank you again for your insight !
Konnan

Back To Top PM Quote Reply

 Posted: Sun Nov 8th, 2009 08:39 pm
  PM Quote Reply
47th Post
iceman
Master Appliantologist


Joined: Wed Apr 6th, 2005
Location: Uzbekistan
Posts: 76
Flavorite Brew: Big Rock Traditional Ale
Status: 
Offline
Hi GG,

They sell those kind of Screwdrivers at Princess auto in a set of 6 for cheap. Part 2920902.

http://www.princessauto.com/tools/hand-tools/torx-keys/2920902-6-pc-torx-screwdriver-set

I got 'em for $6.99 on sale. Which they frequently are.

Hi Konnan,

Earlier in this thread Rob Stercraw solved your problem a little bit more safely. Please consider his solution.  He got another power board.

Otherwise:

Broke the secret screw
Found the power board and fixed
One kid has three eyes!

Last edited on Sun Nov 8th, 2009 10:49 pm by iceman



____________________
iceman
Back To Top PM Quote Reply  

 Posted: Mon Nov 9th, 2009 01:46 am
  PM Quote Reply
48th Post
Konnan
Merit Apprentice Appliantologist
 

Joined: Wed Nov 4th, 2009
Location:  
Posts: 5
Flavorite Brew: iceman
Status: 
Offline
Hi Mr. iceman,

You are again right, but I believe those power boards are not an easy find.

I will try to look on eBay unless you know a better place... we never know.

Thanks again !
Konnan

Back To Top PM Quote Reply

 Posted: Mon Nov 9th, 2009 02:01 am
  PM Quote Reply
49th Post
RegUS_PatOff
Fellow, Academy of Sublime Masters of Appliantology


Joined: Sat Sep 24th, 2005
Location: Milwaukee, Wisconsin USA
Posts: 16509
Flavorite Brew: Indian Head. Black & White
Status: 
Offline
Microwave model number ?

 



____________________
The new repair forums==> http://appliantology.org
Back To Top PM Quote Reply  

 Posted: Thu Nov 19th, 2009 09:54 pm
  PM Quote Reply
50th Post
Konnan
Merit Apprentice Appliantologist
 

Joined: Wed Nov 4th, 2009
Location:  
Posts: 5
Flavorite Brew: iceman
Status: 
Offline
Hello RegUS_PatOff

Sorry for the huge delay...

It's : NNH264W

EDIT :

I think the W is only for color white, so number is really NNH264 or NN-H264 which is similar to NN-S254 if I looked carefully... sorry !

Thank you very much,
Konnan

Last edited on Thu Nov 19th, 2009 10:05 pm by Konnan

Back To Top PM Quote Reply

 Posted: Thu Nov 19th, 2009 10:44 pm
  PM Quote Reply
51st Post
RegUS_PatOff
Fellow, Academy of Sublime Masters of Appliantology


Joined: Sat Sep 24th, 2005
Location: Milwaukee, Wisconsin USA
Posts: 16509
Flavorite Brew: Indian Head. Black & White
Status: 
Offline
 

"Run away !"

from this thread http://applianceguru.com/forum1/21915-1.html

RegUS_PatOff wrote:
I did find someone's repair info on the Inverter Board,

along with some oscilloscope waveforms,
but I don't think you want to go there ...

here's an excerpt:


"The Control signal turns out to be a TTL-level 220Hz square wave where the duty cycle determines the “Power” from the Magnetron.

The Status signal from the PSU is a 110Hz square wave with a fixed 50% duty cycle.

This signal seems to be present when there is a current drain, probably to signal that the Magnetron is warm and operating. 

The Control and Status signals are synchronised to each other, but bear no relationship to AC mains frequency or phase.

Notes:

1. At low power levels, the PSU starts at a higher power level (50%) until the Status signal appears, then drops back to a lower level. 

This could be because the Magnetron filament requires at least the 50% power level for it to heat up, then it sustains itself from back bombardment once RF is being produced.

2. At low levels, the PSU is cycled on and off at the 40% power level over a 22 second period to reduce the average power output."


http://www.mediafire.com/file/zf3ymc2tmdm/panasonic_inverters.pdf

 



____________________
The new repair forums==> http://appliantology.org
Back To Top PM Quote Reply  

 Posted: Thu Nov 19th, 2009 10:54 pm
  PM Quote Reply
52nd Post
Konnan
Merit Apprentice Appliantologist
 

Joined: Wed Nov 4th, 2009
Location:  
Posts: 5
Flavorite Brew: iceman
Status: 
Offline
You are making me sad ! :(

Back To Top PM Quote Reply

Current time is 02:46 pm Tell a friend about this page... all your other friends are doing it! Page:  First Page Previous Page  1  2  3     
- > Do-It-Yourself Appliance Repair Help > The Kitchen Appliance Repair Forum > Panasonic Inverter Microwaves - Advanced or retrograde? Top



Find Appliance Parts & Diagrams Here
Enter a model number, part number, type of appliance, brand, or even a part description.

365-day return policy on all parts ordered through this site!

FAQs | Contact | Apprenticeship | Parts | Model Number Help | Newsletter | Beer

Your Sometimes-Lucid Host:
- Home
"If I can't help you fix your appliance and make you 100% satisfied, I will come to your home and slice open my belly, spilling my steaming entrails onto your floor."


UltraBB 1.17 Copyright © 2007-2008 Data 1 Systems
Page processed in 0.1378 seconds (31% database + 69% PHP). 29 queries executed.

Web Analytics