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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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Searching for "ancient" A/D-converter IC
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 |
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