Here's a tip for anyone still using an old MFT1700 series tester. Mine dates from 2012.
I found about three years in - by 2015 in this case, that the zeroing of the leads on my MFT1720 was becoming increasingly random and the zero would wander about by a fraction of an ohm which became irritating and time consuming. Others talk of replacing leads -(Kewtech are good, and this is certainly worth doing, but it's's not the only problem). At the end of the day, a copper lead is just that. there's no magic. It's the contacts which make the difference.
Cleaning the external leads and instrument terminals with Isopropyl alcohol and cotton buds helps. - But the big win on these ageing instruments is the contact between the terminals "pod" and the main board.
So if you are interested, here's what you do.
Turn the instrument over, remove the batteries, contacts towards you. Remove the two screws adjacent to the fuses.
In between the two fuses you see a rectangular hole and a square one. The rounded plastic boss you can see down the rectangular opening is a robust plastic part of the banana-terminals"Pod". The Pod is the oval-shaped moulding which holds all contacts facing your tummy now. The rear of the terminals are socketed into the main board with male gold-plated spring pins.
Having removed those two screws, nothing except friction holds the "pod" into the case.
So, get a wide blade flat screwdriver and insert it into the rectangular hole, then prise it to push the grey "boss" (part of the oval contacts pod) out of the front of the instrument. You may find first time it's really tight, and one end of the pod wants to release firsts. Hold it straight and lever it out. First time will possibly need quite a bit of force.
The moulding comes right out, and bingo, the source of your problem. You will see spring gold plated pins, which in the factory are lubricated with some Contra-Lube (or similar grease).
These gold contacts can get a little grubby, and a small build-up will add resistance and cause your never ending zeroing problems.
Clean them a little very gently, - if you like with a little isopropyl alcohol. Add a dab of Contra-Lube and push the pod back in.
Bingo, prefect zeroing. I find annual of six-monthy maintenance helps, but I will always do it if I feel the zeroing is beginning to wander a little.
I found about three years in - by 2015 in this case, that the zeroing of the leads on my MFT1720 was becoming increasingly random and the zero would wander about by a fraction of an ohm which became irritating and time consuming. Others talk of replacing leads -(Kewtech are good, and this is certainly worth doing, but it's's not the only problem). At the end of the day, a copper lead is just that. there's no magic. It's the contacts which make the difference.
Cleaning the external leads and instrument terminals with Isopropyl alcohol and cotton buds helps. - But the big win on these ageing instruments is the contact between the terminals "pod" and the main board.
So if you are interested, here's what you do.
Turn the instrument over, remove the batteries, contacts towards you. Remove the two screws adjacent to the fuses.
In between the two fuses you see a rectangular hole and a square one. The rounded plastic boss you can see down the rectangular opening is a robust plastic part of the banana-terminals"Pod". The Pod is the oval-shaped moulding which holds all contacts facing your tummy now. The rear of the terminals are socketed into the main board with male gold-plated spring pins.
Having removed those two screws, nothing except friction holds the "pod" into the case.
So, get a wide blade flat screwdriver and insert it into the rectangular hole, then prise it to push the grey "boss" (part of the oval contacts pod) out of the front of the instrument. You may find first time it's really tight, and one end of the pod wants to release firsts. Hold it straight and lever it out. First time will possibly need quite a bit of force.
The moulding comes right out, and bingo, the source of your problem. You will see spring gold plated pins, which in the factory are lubricated with some Contra-Lube (or similar grease).
These gold contacts can get a little grubby, and a small build-up will add resistance and cause your never ending zeroing problems.
Clean them a little very gently, - if you like with a little isopropyl alcohol. Add a dab of Contra-Lube and push the pod back in.
Bingo, prefect zeroing. I find annual of six-monthy maintenance helps, but I will always do it if I feel the zeroing is beginning to wander a little.
