Megger 1552 Rotary selector

[La Poste]

Greetings.



I have a Megger 1552 and the rotary selector switch seems to be getting a bit tired.

I sometimes have trouble getting it to select the function I want be it RCD test or resistance etc.

My question is has anyone ever stripped one down and cleaned the terminals behind the rotary selector switch?

The tester is still good and it would be a terrible waste just to bin it because of a sticky dial.

Thanks.

 

[keniff]

Did you do it in the end? I'm having the same problem!

 

[MarkieSparkie]

The usual problem with the Megger MFT15xx series (and probably MFT17xx series) function switches is dust and dirt entering the case, usually via the switch shafts and any other unsealed opening. The switch contacts, are wiping contacts mating with etched printed circuit pads, thus any dirt or dust caught under the wiping contacts abrades the contact copper pads and in extreme case wears a groove through to the base glass-fibre and removing the plating from the contacts.
If caught early the switch can be cleaned with an air-duster and vacuum cleaner. Do not, under any circumstance, attempt to clean the switch with switch cleaner (or similar) as this tends to leave a sticky residue that when later covered in dust turns to a very effective grinding paste, accelerating the wear.
Unfortunately, when the problem is detected the wear is usually already advanced. If this is the case the repair is extremely expensive, as it entails replacement PCBs as well as the switch mechanisms, plus the labour cost of the disassembly and reassembly of almost the entire meter.
Remember to keep you test equipment away from first fix areas, particularly when chasing and drilling. Well ventilate the area after completing the first fix, thoroughly clean up the area and allow any residual dust to settle as a precaution before carrying out any testing.

 

[keniff]

That makes sense thanks, do you reckon it's hard to take apart to clean then? Mine is weird you select say 250v ir and it will display continuity on the screen!

 

[MarkieSparkie]

Megger MFT15xx series are not easy to get into. I've recently been using the method Bigbolt suggested a while ago, as it's proved better than the way I used to do it.

Bigbolt's Method:
To dismantle my Megger Series 15xx MFT. I removed battery cover and battery unit remove spare fuse as this will drop out anyway. Next carefully prize off the front label which surrounds all the function dials start this off with a Stanley knife blade or similar it comes off easily once you have got a corner up it is held down by some blobs of contact adhesive so will go straight back on after. You will now see 4 screws remove these with a No. 1 pozidrive screw-driver the front panel will come forward loose and you simply pull off carefully the ribbon cable and then this is off. There is a rubber seal strip around a recess behind the front panel this will fall out so remove and refit later. Next there are 4 screws holding the main body together, remove these and prize the body apart. There are 2 ribbon cables to unplug and the battery pack input plug which goes onto the circuit board this is very flimsy and make a note of its orientation. You can now get at everything... Have fun!! I hope this helps mine is fine now and saved a lot of money so is perfectly do-able.

Your specific problem is probably due to tracking across the selector switch contacts due to the conductive detritus that has been built up.

 

[keniff]

Just ripped mine apart and cleaned all the switch contacts with compressed air in a can and kitchen roll! All is working great now! Thanks alot!

 

[keniff]

All clean! I think the contacts were slightly worn and the dust from this was shorting out!

 

[MarkieSparkie]

Nice one Keith, somebody on here said Megger had quoted £185 to do basically the same job, so you've saved a wad of cash.

 

[oldtimer]

Well as I have said before remember Trigger look after your broom....................................... I am serious about this as I see guys treat their test equipment like it was a 3lb mash hammer in their toolbox now I have 2 25 year old Fluke 71s (i think) one is a spare and the other gets a battery change as and when required I had a 25 year old amp probe until somebody else broke it also it is like washing machines and economics if you get 6-7 out of it great buy a new one and dont bother with repair so look after your gear and after 10 years buy a new one if it breaks down

 

[keniff]

That's what I couldn't really understand, iv looked after mine, it's got its very own ck technicians bag mine was not filled with dust but the remains of ground up contact bits!! But i can imagine if it was dusty aswell!

 

[adamh]

just done this and its cured mine i think i need to get a new sticker for the top though!

 

[grantr37]

contact cleaner spray, or cotton soaked with wd40

 

[grantr37]

you can re-tin the pads as well with silver solder and a reflow iron....