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HV diode

enli

Jan 14, 2016
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Microwave Sharp R520LK, diode T3509-6D, after looking around for replacement, think this is a 300mA, 9KV diode, and is no longer available from Sharp. Not electronic savy enough to know what can be used as replacement. Local appliance part store has "universal diode", but they could not tell me it's rating or anything about it, so looked some more and found several 12KV, 300mA diodes listed. Can these be used as replacement? Ran test on magnitron, transformer, capacitor and diode was only thing that was way out of whack. When turned on everything seemed to be working, but was making really loud humming and zero heat. This happened all at once, worked fine and next time it didn't. Replaced one of the door safety switches on this unit about 2 years ago, but other than that has worked fine for about 7 years. Advice and source for replacement diode would be highly appreciated
Enli.
 

dorke

Jun 20, 2015
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Well,
The 12KV diode is a proper replacement.
It has a higher voltage breakdown which is fine and a bit higher forward voltage drop which is less fine, but should be O.K.
see the datasheet here

I think it should be possible to get the diode one you have from a Sharp service center near you.
Or on Alibaba/aliexpress
 
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enli

Jan 14, 2016
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What am I missing here? Alibaba wants you to buy minimum units that end up costing $100 or so, how do you buy 1? Thanks for info, now if I can find one. No help from local Sharp service center or electronics stores. Where now?
 

dorke

Jun 20, 2015
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You can use the 12KV one, should work fine.
What is the marking on it?
 
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enli

Jan 14, 2016
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Found this one at HV STUFF think it would be okay? Doesn't appear to have cathode markings, but guess I could test for flow direction?

300mA 10kV 100nS High Voltage Diode HV Rectifier High Frequency

Repetitive Peak Reverse Voltage
10kV
Average Forward Current 300mA
Maximum Surge Current 30A
Avg. Forward Voltage Drop 28V
Peak Reverse Current 5uA@25°C
50uA@100°C
Reverse Recovery Time 100nS
Dimensions Φ7mm×21mm(Φ0.28inch×0.84inches)
Terminals Axial Lead
 

dorke

Jun 20, 2015
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"Avg. Forward Voltage Drop 28V"
That is high compared to VF =9V(max) of the T3509 and 10V of the the T3512
I wouldn't replace it with that.

Here is the T3512 for 0.99$ ,use it.
 

enli

Jan 14, 2016
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Thanks dorke, ordered it today, but will be a couple of weeks getting here. Will update when progress is made
 

enli

Jan 14, 2016
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Know it's been a while, installed new diode and results were same! Ran test on NEW diode and it seems to be BAD! Guess $.99 is NOT the way to go. Upon powering microwave up (after replacing diode) arcing was observed in the magnitron. Shut it down immediately and magnitron still checks out okay. Any thoughts?
 

elebish

Aug 16, 2013
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If the diode is ok and arcing is occurring, the magnetron is putting out, however there should be no arcing in the oven unless the magnetron is improperly mounted. There should be no arcing inside the magnetron unless it is defective. Make sure the oven chamber is clean and void of food particles. Did you purchase the diode from the site I gave you? If so, the ground side of the diode should already have a lug for grounding.
 

enli

Jan 14, 2016
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elebish,

Ordered a T3512 from site dorke had listed above, might try the $12 one you suggested next! The arcing was inside the magnetron just below where wires are attached, this is NEW development after changing diode. Could wrong or bad diode cause this to happen? No arcing in the oven and never removed magnetron so don't think improper mounting is an issue. Should I order the 9KV diode 450mA or the 12KV 350mA, not exactly sure which one is correct for Sharp R520LK, T3509-6D was the marking on original diode and I am guessing this means 9KV. Not being savy about diodes, but could you use any of those listed at this site?
 

elebish

Aug 16, 2013
177
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Microwave Sharp R520LK, diode T3509-6D, after looking around for replacement, think this is a 300mA, 9KV diode, and is no longer available from Sharp. Not electronic savy enough to know what can be used as replacement. Local appliance part store has "universal diode", but they could not tell me it's rating or anything about it, so looked some more and found several 12KV, 300mA diodes listed. Can these be used as replacement? Ran test on magnitron, transformer, capacitor and diode was only thing that was way out of whack. When turned on everything seemed to be working, but was making really loud humming and zero heat. This happened all at once, worked fine and next time it didn't. Replaced one of the door safety switches on this unit about 2 years ago, but other than that has worked fine for about 7 years. Advice and source for replacement diode would be highly appreciated
Enli.
Try this site. I seem to think you have a bad magnetron which you can purchase on this same site:
http://microwaveglasstrays.com/shop/-c-23.html
 
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