Hameg HM8122 frequency/counter

[martijn_klasing]

Is there anybody has has experience in repairing a Hameg HM8122 frequency/counter? The left two digits on the display are not working. These give the sign and the exponent of a measured value. Beside this malfunction the apparatus is working correctly and in spec.

 

[bertus]

Hello,

I can not find a service manual.
The user manual can be found here:
https://elektrotanya.com/hameg_hm8122_universal_counter_um.pdf/download.html
There is a partlist on page 41 of that manual.

Bertus

 

[kellys_eye]

First, determine whether the display is multiplexed or not. If it's multiplexed and the rest of the display is working then you likely have a dud display. If they are driven independently you will need to chase the decoding (usually hex-to-7seg decoders).

In this case I suspect a simple dry joint but without details (pics and schematics) this is guesswork.