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A simple, low-speed model from the British radio manufacturer. While only 4 digits are displayed it is possible to get 6 digits of precision by taking a reading on each of the 3 provided gate periods.
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| Serial Number: | N0653 |
| Year of Manufacture: | 1963 (Capacitor dated May 63). |
| Date of Receipt: | 2008 Dec 18 |
| State upon Receipt: | Clean, very good condition. Count is incorrect on "*1" setting. MSD "0" bulb burned out. |
| Repair Date: | 2008 Dec 19 |
| Procedure: | MSD "0" bulb replaced. (Several replacement bulbs provided in unit.) Loose solder joint on lead of LSD "1" bulb resoldered. Fully functional. |
| Repair Date: | 2008 Dec 21 |
| Symptoms: | Count is incorrect on "*1" setting. |
| Analysis: | Gate period is only about half a second, it should be 1S. 2nd decade divider is counting modulo 6 rather then 10. 2nd stage flip-flop is not toggling but does pass a pulse through 1 for 1. |
| Solution: | V3 of 2nd divider has leaky CE junction. Replaced with 2N1377. |
| Repair Date: | 2008 Dec 21 |
| Procedure: | Reassembled. Fully functional. |
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.. | RACAL SA.520 | ..
Early Digital Test Equipment |
bhilpert |