|Functions: ||basic four, constant|
|Number of Digits: ||8|
|Display Type: ||LED|
|Logic Technology: ||LSI|
|IC Complement:||Texas Instruments TMS 0103
Texas Instruments SN75491 (2)
Texas Instruments SN75492 (2)
|Batteries: ||6 NiCd|
|Power Connector:||(?) V, 3-pin special|
(alternate/no batteries: 7.5::9 VDC, - left, + centre, viewed from rear)
|Tech. Data Level: ||2|
|Tech. Data Source: ||RE|
|Tech. Data Pages: ||1|
|Tech. Data:||Schematic (pdf)|
A classic example of one of Bowmar's early models.
Bowmar OEM'd models for many name brands and retailers.
Special circuitry implements a battery-saver timer that blanks the display after 15-20 seconds of idle.
A solitary segment (g) of the middle digit is left illuminated to indicate the unit is on.
Pressing any key brings the display back, the "D" key is included to bring the display back without effecting any other operation.
- Unit Log -
|Serial Number: ||G12950|
|Year of Manufacture: ||1972 (batteries stamped with 7232)|
|Accessories: ||With case and manual.|
|Date of Receipt: ||10 Mar 2002|
|State upon Receipt: ||Good physical condition, minor corrosion on some screws and printed circuit traces.|
|Current State: ||Fully functional (2020 Feb) (14 Mar 2002).|
|Date: ||10 Mar 2002|
|Date: ||13 Mar 2002|
|Procedure: ||Soldered keyboard connections replaced with detachable pins.|
|Date: ||2020 Feb|
|Symptoms: ||Stopped working (display disappears) in course of having been opened for further analysis and internal photos.|
|Analysis: ||Digit scanning is intermittent, waveforms collapse to near-high.
phiD9 & phiD10 are as usual, suggesting problem may be on U2,3 side rather than U1.
PCB trace for ground line to U2 & U3 bad due to old corrosion from battery.|
|Solution: ||Wire soldered in to circumvent corroded section of trace.|