Electrical Emergancy

I have three multimeters;

An Avo 8 which I never use - accurate, ridiculously bulky and takes an impossible to get battery for resistance readings. Belongs to a different era, I have had it since the 1960s.

A small, pretty accurate analogue meter that I was given in the late 1980s, again, which I rarely use.

A cheap digital multimeter which I have probably had 10 to 15 years (ish) which I use all the time.

Anyway today I had a small electrical (solar) problem in my camper and for some reason I couldn't immediately find my digital meter so I grabbed the small 1980s meter. Set it to 50V DC stuck it on the 12v battery to test it (as I said I never use it) and it went full scale. Strange! even stranger it went full scale on 200V DC too.

Anyway to cut a long story short I went and found my digital meter, fixed my problem and decided to look at the meter. This is what I found.





Oh well! I spent the afternoon with some vinegar, alcohol and a toothbrush cleaning up the mess and resoldering some of the connections.

I really must be more careful! Absolutely stupid, it only needs batteries for the resistance reading I should just leave them out - even worst that was not the problem with it, it still goes full scale on any setting. More work tomorrow? or in the bin?

Re: Electrical Emergancy

I hope you manage to fix it Bruce.

I've made the mistake of measuring AC mains on the Ohms ranges once or twice. Just got distracted and forgot to change the range. Do that with an AVO 8 and it just pings the cut-out. Do it with a small analogue multi-meter and the effect is the same as the photo. Changing resistors repaired mine and it's still working OK. Just as well because I sold the AVO 8 when I stopped work.

I keep thinking I'll buy a digital meter but I mostly only have to measure battery voltages, mains voltage and continuity these days. The old Altai repaired analogue multi-meter still does this OK.

Re: Electrical Emergancy

Crikey I would have no clue.

Re: Electrical Emergancy

Is it worth the effort when you can get a new multimeter from RS for around £16 and probably cheaper elsewhere?

Re: Electrical Emergancy

Avo 8 high resistance range batteries (15 volt) are readily available on eBay.

Re: Electrical Emergancy

Multimeters are classic examples of equipment that probably contain neglected batteries Bruce, especially when you've retired and don't use them for long periods. I keep an analogue meter in my toolbox mainly for continuity testing and have had to perform the same job as you.

I now write the date on the back of all my multi testers when they had their last battery change. Now you've posted that, tomorrow I shall inspect all my meters...... Thanks Bruce.

Re: Electrical Emergancy

To be honest it is not a meter I like very much. It is probably just a minor whinge but I prefer meters with the Amp range on a separate socket so that to measure amps is a deliberate act. Too easy to flick the range switch over the amp setting and (effectively) put a dead short across whatever you are measuring. This meter has the 10 amp reading on a separate plug but the mA range uses the normal + & com.


Probably not worth it but it might be something really simple so it is worth having a look (what else would I be doing?) and as I have two other meters I wouldn't replace this one anyway.

Late edit:

Started to reverse engineering the meter and having a very frustrating time trying to get the circuit board out when I glanced at the leads and had a brainwave. Cut the probes off the leads, soldered on clips in their place and chucked the rest in the bin. Now my digital meter has a set of leads with clips as well as probes. Very pleased, as they say in Thailand, Happy Ending!