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MFJ-259B polarity reversal damage

 

Hi all,

anybody here experienced with polarity reversal damage of MFJ-259B please?
My father damaged it by his mistake and he is totally frustrated so I would like to repair it for him.
Just want to ask what should be burned and where to start...?

Thanks, 73 - Petr, OK1RP
 

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Call MFJ, the oval support. They are really helpful and have been through the problem before... Worse case, they will repair it. I was charged $75 and a bit for the replaced parts.

--
Sent from my Android phone with Mail. Please excuse my brevity.

On 8/31/22, 11:58 AM Petr Ourednik <indians@...> wrote:
Hi all,

anybody here experienced with polarity reversal damage of MFJ-259B please?
My father damaged it by his mistake and he is totally frustrated so I would like to repair it for him.
Just want to ask what should be burned and where to start...?

Thanks, 73 - Petr, OK1RP

 

Hi Don,

many thanks.
I emailed to MFJ in parallel and I got short reply "schottky diodes surface mount 2820s"...
Which is surprising me a bit as I expected some damage around the power supply circuitry but these diodes are in RF detector part.
In worse case something like $75 + s/h would not be big issue for me just as I am in central EU so i am worrying if the cost will not be a bit high.

He could smell the stench when he reversed the polarity of the ext. power to his MFJ-259B.
So if the SMD Schottky 2820s could use this problem it would be nice.
I asked MFJ support kindly for some schematics or details to locate them and confirm it?

In all cases many thanks Don !

73 - Petr, OK1RP
 

This might help:

Bob N5TX
 

There is a nice rectifier on the external power input that should/might protect the rest of the meter.
Bob N5TX
 

Hi all

any hint where to buy genuine?schottky diodes surface mount 2820s for MFJ please??

Petr, OK1RP
 

Mouser


RF Microwave


everything RF


eBay, Chinese, but what isn't these days?
 

Thanks Jeff
eBay is high risk to get fake…
Unfortunately Mouser has out of stock. ?

So RF Microwave only to get them…

73 - Petr. OK1RP

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