At your risk. Take safety precautions. Any voltage or current can be dangerous.
This seems to be a Geiger Muller counter. Operates with a 9V battery.
It must have been read somewhere that they synthesize counting.
This must be done by the 4551 IC converging voltage into a proportional pulse frequency.
https://www.bucek.name/pdf/xr4151.pdf
I does not count at the moment, although it used to work. Digital circuit and display seem to operate.
Hoping it is an electrolytic capacitors age problem.
On a small circuit board are 2 10μF/16V and on a larger digital board is one 22μF/25V. ICs are 4011, 4012BE, 4040BE, 4060. All start with HCF and end with BE. Made by ST.
Transistors are C558B, C548C and a bent one which can't be read. All transistors are Philips having the silver painting and the PH logo.
The smaller board has a C558B transistor and a 8 pin IC RC4151N.
There are also electronics inside the electron tube housing. This must be a step up oscillator circuit and high impedance active device circuit.
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