Sanyo Combi Microwave EM-D9553SN

[clicon357]

Morning,

We’ve a “much loved” Sanyo Combi Microwave, EM-D9553SN here, the second Sanyo tbh and it’s given years of great service. Oven and grill still work but I think the magnetron has packed up. It was working last night then made a single noise like if something metal was in there (there wasn’t). Thereafter the microwave section isn’t working. I’ve had the top cover off and noticed a burn mark on the connector. SWMBO only mentioned last night that “it’s been sparking for a couple of weeks”. The waveguide appears intact and undamaged from a quick look.

https://flic.kr/p/2qwBSWh

The magnetron is a Toshiba part 2M253H (IF).

https://flic.kr/p/2qwAjqp

I can find plenty of new 2M253H ones but not with the (IF) suffix. Is there something else that will fit?

Appreciate it’s an old model but it seems a shame to scrap it. Plus my daughter is autistic and used to it. Not the worst case if I have to get a new one (microwave not daughter).

Thanks for looking.

(apologies for the Flickr photo links, I tried uploading attachments but got a message that said “You have exceeded your usergroup’s upload quota of 19.5kb by 2.62MB“)

[electrofix]

that could well be just a bad connection

Do you realise you are dealing with 5000 Volt DC and in fault conditions there is enough stored energy to kill you after you have unplugged it

do you know the safety proceedures to follow to keep safe ?

Dave

[clicon357]

[USER=”4209″]electrofix[/USER] many thanks for that.

Yes well aware of the potentially lethal voltages inside thanks. The day job involves safe isolation etc.

As I understand it, from some further reading since I posted, the (IF) suffix on the Magnetron dictates the mounting. I’ll remake that crimp as a first port of call. I wonder if another 2M253H could be got, taken apart and utilise the (IF) mounting from the original?

Thanks

[electrofix]

you will be able to get a mag. can point you at that one

first do the joint

magnetrons have 2 power sources , a high voltage on the anode to earth and a low voltage high current for the heater. if the joints fail the heater wont be hot enough to work. had that fault loads. found it best to crimp and solder the joint as its often solid wire

Dave

[clicon357]

A little bit of investigating just now. All measurements with leads removed:

The capacitor measures nom 1uF

Across the magnetron I’m seeing nom 0.3 ohms.

Though the clear insulating boot on the red lead to the magnetron appears scorched, the actual connection doesn’t show any sign of overheating. Still a potential high resistance joint? I could solder it.

https://flic.kr/p/2qwFzJ3

I have found though the 750mA fuse has blown!

https://flic.kr/p/2qwFm4w

[clicon357]

This big diode appears open circuit!

https://flic.kr/p/2qwFBXL

So I’ve found the duff fuse and diode any suggestions as to the cause?

Thanks

[clicon357]

Slight correction…

I read that a standard multimeter might not have enough forward voltage to check these diodes. Went and found a good 9V battery and like this got apparent continuity one way:

https://flic.kr/p/2qwGAUN

[electrofix]

well you wont know till you replace fuse

if the manetron is arcing internally you wont know till its powered up with a new fuse

Diode will be fine. if they go its normally short circuit

caps can go short too but you getting a good reading on it

you have only measured the heater on the magnetron but now set multimeter on the highest ohm scale. one lead on either of the mags terminals and the other one on the metal casing. you should get no reading at all. if you get any mag is scrap

Dave

[clicon357]

“you have only measured the heater on the magnetron but now set multimeter on the highest ohm scale. one lead on either of the mags terminals and the other one on the metal casing. you should get no reading at all. if you get any mag is scrap”

Forgot to say I did that too, with the meter set on the 2K resistance range. No reading from either terminal to the metal casing of the mag.

[electrofix]

prob ok but do it on a meg ohms scale before you go further

Dave

[clicon357]

electrofix wrote: prob ok but do it on a meg ohms scale before you go further

Dave

Thanks. As in “megger it” with an insulation resistance meter? Mine is an old 500V job.

[electrofix]

that will be perfect

Dave

[clicon357]

OK, a bit of early morning meggering: I measured infinity between the magnetron casing and either terminal:

https://flic.kr/p/2qwMMVu

As aforementioned, across the same two magnetron terminals on the low resistance range I’m seeing nom 0.3 ohms.

[clicon357]

I’ll order some fuses this morning. Noticed they’re damn tight in the end caps!

[electrofix]

some fuses are fixed in the end caps and you have to get the complete fitting

Dave

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