Megger MFT1720

[gazzagadget]

Hi all,
Does anyone know how to access the upper innards of a Megger MFT1720?
I bought a used one about 3 years ago, it's been working fine.
I suspect I may have developed a rotary switch issue.
I found a site that shows opening a MFT 1552 for a similar issue but the 1720 is different construction.
The left rotary switch does not quite align with the label and it feels like something is not as it should be.
Intermittently it starts beeping while the switch is set to 'off' with the display showing 'off' and briefly changing to 'err 79' when it beeps. Removing the batteries, rotating the switch then re-inserting the batteries often gets it back to normal.

 

[conny]

Could it be as simple as fitting a new set of batteries?

 

[gazzagadget]

Thanks for the suggestion, that’s the first thing I tried.

I used it today and it behaved itself.
I now remove a battery if it’s not going to be used imminently. When the problem is happening 10-20 seconds after installing the batteries three horizontal bars appear then ‘err79’ while the left rotary control is set to off.

 

[Ebeam]

Hi. I work for a company that calibrate MFTs, PAT testers, etc. It's a reasonably common fault with the Meggers . It's actually a fault with the switch itself.

 

[gazzagadget]

Hi Ebeam, thanks for that info, very useful.

I’m an ex TV & video engineer so very familiar with electronics and fault finding. I was suspecting something linked to the rotary switches as the fault condition cleared after the switches were ‘excercised’ for a while.
But I cannot figure out how to get to the insides and didn’t want to start forcing things to find a way in if someone one here could provide some clues. Do you know or have any suggestions how to access the switches?
Another thing that makes me suspect some past problem or meddling with the rotary switches is the left (main) rotary switch is a few degrees out in relation to the markings on the label. Maybe just the knob is not fitted correctly or something more?

Thanks in advance for any advice.

 

[Ebeam]

Hi, gazzagadget .I'll try and have a word with the engineer who told us about the problem ,see if he'll tell me how to get at the switches.

 

[gazzagadget]

That would be great, thank you.

 

[Ebeam]

Hi the engineer at work says they have a 3 year warranty.

Try ringing Seaward on 01915 863511

Or email [email protected]

 

[gazzagadget]

This is a long time out of any warranty but thank you for trying to help.
It looks like I’ll have to start levering things to try and find the way in.

 

[Ebeam]

No problem I did ask about how to access the switches but as our company is an approved agent, he said he'd have to kill me if he told me .

Good luck ,please let us know how you get on.