| Manufacturer: | Monsanto |
| Model: | 110A |
| Year: | 1968 |
| Schematic: | RE |
| |
| Max Rate: | 85 MHz? |
| Display: | NIXIE |
| Digits: | 7 |
| Logic: | RTL, ECL |
|
The maximum count rate on this unit needs to be measured. The first decade uses ECL flip-flops (MC1013) which are specified to 85 MHz. However, the second decade is labeled as "12.5 MHz", which would suggest the first decade is good to 125 MHz. Whether or not the rest of the input circuitry keeps up with either of these possibilities is unknown.
- Unit Log -
| Serial Number: | 916-A-561 |
| Year of Manufacture: | 1969 (Components stamped with 6745 - 6927, 1968 in foil of PCBs). |
| Date of Receipt: | 1998 Dec |
| State upon Receipt: | Good physical condition. Functional. Missing power cord with oddball connector. Fan bearings are bad, noisy. Unit had seen previous repairs:
- Some ICs on one decade counter module had been socketed and replaced (7647 dates on replacements). This provided cross references for some IC types.
- Transistor pairs on A and B input boards appear to have been replaced. |
| Repair Date: | 1998 Dec |
| Procedure: | Cleaned. |
| Repair Date: | 1998 Dec |
| Procedure: | Oddball circular power connector replaced with IEC standard. |
| Repair Date: | 2006 May 11 |
| Procedure: | AB Interval mode observed to be not working. A will trigger the count to start but B will not stop it. Traced to IC MT-4. Output MT-4.2 is not pulling high enough to send MT-4.5 low. Isolating MT-4.11 (V+) shows it to be open to all other pins. IC removed for replacement, but is OK after heat application during removal. Socket installed and old IC re-used. |
| Repair Date: | 2006 May 13 |
| Procedure: | Fan cleaned and oiled. |
| Repair Date: | 2009 Feb 16 |
| Procedure: | AB Interval mode problem (see 2006 May 11) is back. MT-4 (SC2217) replaced with a MC789. |
| Repair Date: | 2009 Feb 16 |
| Procedure: | Fan disconnected. |
