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A slightly enhanced version of the Canon 130: 16 digits instead of 13, and an additional accumulating memory.
| Notes: |
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Closer view of the keyboard and display.
Note this unit does not have the "M+" and M-" keys,
contrast with the 161 at Rick Bensene's site.
Cover removed.
The logic is contained on 11 circuit boards plugged into a hand-wired backplane on the left side.
The connectors on top and the large white bundles of wire are the connections to the display.
The display is not multiplexed, as a consequence there are over 190 wires connecting the 16 digits of the display.
The power supply is below the keyboard.
Side view showing the backplane wiring and the CMU (Controller/Monitor Unit) attached.
The CMU plugs into an extra card edge-connector provided on the calculator.
A toggle switch below the connector switches control of the clock over to the CMU.
Board 33, one of the 11 circuit boards containing the calculator logic.
The 11 boards are identified as 30 thru 40 in the last two digits of the part number, seen here in the lower left corner of the board. The boards are sequenced front to back when inserted in the backplane.
This board contains:
Four bad transistors have been replaced on this board, distinguishable in black plastic TO-92 packages. The Ge transistors in machines of this period have quite a tendency to fail. They have been replaced here with the common Si 2N3906. |
Board 33 accessed for service with a home-built card extender.
View from the rear of board 33 under service.
The two test clips are probe leads from the CMU, clipped onto flip-flops in the ME register.
The boards can be very difficult to remove from the backplane.
Shown is a board puller made from a bicycle spoke bent into a U and two hooks formed on the ends.
This board extender was constructed from some sheet aluminum, two edge-connector receptacles and the edge-connector fingers cut from two scrap circuit boards.
A closer view of the CMU.
The CMU displays various internal state registers of the calculator, and provides manual control over the clock.
The clock can be slowed down at a variable rate or single-stepped.
Also provided are two binary probes to monitor arbitrary points in the calculator via clip-on test leads.
| 700369 | |
| 1966 (variable resistors in power supply stamped with 6604, transistors stamped with 6E.) | |
| Power Supply Board labeled with "1964.7 H.SATO" in copper foil. | |
| 08 Dec 2000 | |
| Brownlee Office Equipment. See source note for Canon 130. | |
| Good physical condition. Multiple and inconsistent functional problems: pressing the clear key does not clear all digits; pressing a numeral or operation key results in random numerals in the display and may turn on the overflow lamp. Internal test-mode switch seized. |
| 09 Dec 2000 | |
| Broken internal test-mode switch replaced. Unit disassembled for cleaning. |
| Jan 2001 | |
| Extender Card constructed to assist in repairs. |
| 07 Jan 2001 | |
| Original power connector replaced with IEC standard. |
| 07 Jan 2001 | |
| Pressing Clear key results in a display of "000000004NNNNNNN" where N = (7 and 9 digits on simultaneously). | |
| The 7-and-9 display results from a value of 15 in a digit register. The symptoms suggest a stuck-high flip-flop in the 4 bit of digit 8. The not-Q, or "0", transistor in the flip-flop, while it would switch (had gain), would not hold the state. | |
| 2SB329 transistor IR15-4-0 replaced with 2N3906 (board 34). |
| 07 Jan 2001 | |
| A slipped test lead resulted in brief application of positive potential to the SP-I line. The display was now completely static with random digits. | |
| Output buffer transistor for SP-I had developed a CE short. | |
| 2SD77 transistor replaced with 2N3904 (board 32). |
| 09 Jan 2001 | |
| Multiple symptoms which all turned out to have a common source: the multiply-bar randomly chooses to increment or remain at digit 1 during digit entry; the decimal point does not move with digit entry; multiply operations ignore all digits of the second operand except for the first, i.e.: 2*123=200; divide results in an infinite loop. | |
| Focusing on the multiply-bar problem: The signal on the R input to flip-flop DC1 was not as expected. Possible intermittent problem with base of transistor. Transistors in DC1 replaced. No improvement. Trigger capacitor substituted. No improvement. Finally FD was observed to be alternating with CP but at a random phase relationship to P-8. RFD is always logic-1. Conjecture that FD should not be alternating at all. If so RFD should not be logic-1. Logic-1 traced back to shorted transistor in buffer for RPABD. The random aspect of the problem resulted from the alternating of FD which presented a 50/50 probability of FD being in the 'correct' state when a key was pressed. | |
| 2SB329 transistor in buffer for RPABD replaced with 2N3906 (board 36). |
| 10 Jan 2001 | |
Lamp repairs:
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| Jan 2001 | |
| Controller/Monitor Unit designed and constructed to assist in solution of next problem. |
| 22 Jan 2001 | |
| Arithmetic operations intermittently result in random digits in the display. | |
| Schematic analysed to determine data flow during addition. Bad data then observed to be emerging from ME register during CC6. Source of bad data traced to flip-flop ME14-2. The flip-flop sometimes sticks high. The not-Q, or "0" transistor would not always stay off. Observation of base and collector signals with a scope suggests a leaky BC junction. Essentially the same problem as that of the incomplete-Clear repair of 07 Jan 2001. | |
| 2SB328 transistor ME14-2-0 replaced with 2N3906 (board 33). |
| 22 Jan 2001 | |
| Numeral 7 of digit 14 does not light. Lamp is not burned out. | |
| Associated driver transistor found to have open BE junction. | |
| 2SB77 transistor replaced with 2N3906 (board 33). Unit now restored to full functionality. |
| 07 Nov 2010 | |
| Arithmetic operations result both 7 & 9 illuminated throughout the display (display for digit value 15). | |
| CMU used to follow state transitions and trace data flow during add. Transitions are (2->)3->6->7, 2 only occurring if decimal points have been entered. 3:IR->ACC, 6:ACC->ME. Data is lost in ME. Traced to transistor ME15-1-0, will not turn on, base remains slightly negative even when C of opposing transistor is shorted to ground. | |
| 2SB328 transistor ME15-1-0 replaced with 2N3906 (board 33). |
| 07 Nov 2010 | |
| Briefly after above repair; hitting "=" key with value in display erratically results in various digits being cleared, 111*111->12221, other arithmetic errors. | |
| Traced to transistor ME14-1-1, will not turn on, behaviour just like ME15-1-0. | |
| 2SB328 transistor ME14-1-1 replaced with 2N3906 (board 33). |
| 17 Nov 2010 | |
| CMU improved with Step-Digit and Interval functions. Bounce on new controls is a little odd. With 0.01 cap on switches, there is an action on both push and release of switch. With no cap, there is an occasional double-pulse, but tolerable. Jumpers to two caps cut to take them out-of-circuit. |
| 17 Nov 2010 | |
| Unused connector pin NTL connected to -10V on calculator to supply power to the CMU, to avoid the extra clip lead from the CMU. |
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Canon 161
Calculators | Integrated Circuits | Displays | Simulations EEC |
bhilpert |
