Attention: FUP2 sci.electronics.repair
Dear Experts
Maybe somebody here can help me. I'm searching for a certain 3 digit ADC-IC (18 pin DIL) for a Kamoden DM-200 DVM. Unfortunately the IC I'm searching for was already missing when I got the DVM for repair.
The IC seems to be part of a two chip converter solution. On one hand, it controls the 3 switching transistors for the 3 digit LED display (common cathode). On the other hand it generates the BCD word for the decoder IC MM 74C48. Additionally it may (partly?) contain a dual slope ADC. I've found out the following pin functions:
Pin 1: Vss/ground 3: Gate JFET (E 204) 4: Source JFET; foil cap A (100 nF) 6: Vss/ground 7: Base transistor digit 3 8: Base transistor digit 2 9: Base transistor digit 1
10: BCD "A" 11: BCD "C" 12: BCD "B" 13: BCD "D" 14: via capacitor 1 nF to ground 15: Vdd (?) 16: Drain JFET; foil cap B (100 nF) 18: foil cap A (100 nF); foil cap B (100 nF)
Okay, I've already done a lot of research. I found out that none of the following IC's will fit:
Siliconix LD 120/121 LD 122/121
RCA CA 3162E
TI TL 50x
Ferranti ZNA 116E
AD AD 2020
Any suggestions?
Full of hope
Reinhard