FAULY MOVING COIL MULTIMETER (ALTAI HC-2020S)

C

CarlH

Newbie
Joined
Oct 3, 2023
Messages
2
Helped
0
Reputation
0
Reaction score
0
Trophy points
1
Activity points
23
My old, but formerly very good. Altai moving-coil multimeter, model HC-2020S, has developed a fault.

The fault is apparent on DC voltage.

The 0 to 10 Volts DC scale seems still to work correctly (eg, for a 9 Volt smoke alarm dry single-use battery). This voltage is also displayed correctly on the 0 to 50 DC scale.

I need the 0 - 50 Volts DC scale to check the voltage of an (off the car) 12 Volt car battery. However, this voltage (at most, around 13 V) causes the needle of the 0 - 50 Volts scale to shoot up to the end of the scale (slightly beyond the 50 Volts DC maximum point - probably up to a limiting stop for the needle

The same behaviour happens with the car battery on the 0 to 250 Volt DC scale. The needle shoots up to beyond the 250 Volt point.

Is this fault due to a simple fault like a faulty resistor on the PCB?

If so, how do I find the faulty resistor (or whatever) in order to replace it/them?
 

Sort by date Sort by votes
I know the temptation to repair an old meter like that is strong but in reality they are almost impossible without a schematic and a source of precision resistors. What has probably happened is one resistor has changed value but you will find it almost impossible to trace without a schematic showing values and another meter to check the component. The resistors in those meters were custom made to specific values, you won't be able to buy them in a store. With digital meters being far more accurate and so inexpensive, repairs are not a realistic option.

Brian.
 

Upvote 0 Downvote
Thanks, Brian!

That's good standard advice, of course. Thanks for your rime.

However, a moving coil meter should show (by needle flutter) a rapidly changing (up and down) voltage. Digital meters can't, AFAIK, do this. I need that very rapid response to change, at least occasionally.

So can you, suggest a new moving coil voltmeter with a really clear dial, and which has a good reliability reputation? An analogue multimeter would be fine, but I don't actually need facilities such as as current, resistance, transistor test in addition to voltage. However, I do need a wide range of test voltage modes, so it will probably have to be a multimeter (or several single voltage meters!).
 

Upvote 0 Downvote
You must log in or register to reply here.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…