| HP 9830 | Hewlett-Packard 9830 Unit Log |
| Serial Number: | 1303A00748 |
| 1973 to 75 (date stamps on various ICs) | |
| Date of Receipt: | 2013 Mar |
| Source: | R.F. |
| State upon Receipt: | Rather beat up. Slight warp in top lid, rear plastic bumpers broken, crack and deformation in plastic in right front corner pieces, several keys broken, some screws missing. Non-functional. Came with Infotek CPU. |
| Date: | 2013 Mar |
| Procedure: | Dismantled for cleaning. |
| Date: | 2013 Mar |
| Procedure: | Power supply checked. Power switch not making contact. Opened for cleaning and repair. Contact restored. Power lamp burnt out. |
| Date: | 2013 Mar |
| Procedure: | Various panels cleaned. Keycaps cleaned. Keyboard switch matrix swapped for alternative. Alternative had 25 broken or missing switches but base was in better condition. Switches removed from original and used to populate alternative. |
| Date: | 2013 Mar |
| Procedure: | Keyboard reassembled. "/" key repaired, cracked mounting glued. f0 key had been previously replaced with an f7, replaced with f0 from alt keyboard. Keyboard was well-used, numerous common keys are worn from fingernail impact. Deformed corners of keyboard plastic cover softened with heat strip and straightened, 4 cracked areas glued. |
| Date: | 2013 Apr |
| Procedure: | Cassette: optical tape detector bulb burned out. Replaced with small red LED. Testing shows LDR R only goes a few K below the 18K required to trigger, so should keep an eye on it in future. |
| Date: | 2013 Mar |
| Procedure: | Cassette: insulation on optical tape detector leads worn through. Patched with hot glue. |
| Date: | 2013 Mar |
| Procedure: | Cassette: cassette-in micro-switch does not click but still functions. |
| Date: | 2013 May 11 |
| Procedure: | Reassembled, Infotek CPU replaced with HP CPU board set. Functional after installing correct ROM: plotter ROM initially mistaken for BASIC II ROM. Error 1 at start, error 80 after any operation. Functional with Infotek FastBASIC II ROM. |
| Date: | 2013 May 11 |
| Procedure: | Some calculations produce incorrect results. Intermittent. Seems to be related to BCD 2-bit. |
| Date: | 2013 May 25 |
| Procedure: | Plotter and InfoTek ROMs dumped. Note HP ROMs need fairly precise negative supply on pin 1: 2.3V will result in high output levels for zeroes, 2V is proper. 5V supply switches on Infotek ROM are marginal: need decent drive to bring Vcc up to just 3.9V. |
| Date: | 2013 Nov 27 |
| Procedure: | Intermittent arithmetic fault traced to bad BCD1 bit in BCD ALU. Bit pattern is present but high level intermittently drops to less than 1V. BCD1 circuit opened at ROM2-Y1 pin (U14-11.11) to assess whether ROM output, pull-up R, or A-reg input is bad. Appears to be ROM output. New ROM burned and substituted. Problem still present. U14-5 (5495) replaced with 7495. OK. |
| Date: | 2014 May 07 |
| Procedure: | Wires to power switch cut and resoldered due to fraying strands. |
| Date: | 2015 May 06 |
| Symptoms: | Tape commands hang for awhile with no tape movement. Manual rewind works, although rewind command will lock it out. |
| Procedure: | Traced to bad input U62-17.9. U62-17 (7402) replaced. |
| Date: | 2024 Jun |
| Symptoms: | Failure to boot (no lazy-T at power-on). Fan comes on, tape rewind will work, but no other commands work. |
| Analysis: | With ROM & RAM boards removed so processor is cycling through the address space, observed that nROMA7 is not changing. Traced to bad output U82-33.3. Output appears as open-circuit - pulls neither high or low. IC tested OOC also shows unconnected inputs 1,2 reading >4V rather than normal <2V. |
| Solution: | U82-33 (7400) replaced. |
| Date: | 2024 Jun |
| Symptoms: | While working on fail-to-boot problem, after re-insertion of M-Register board, contact on many pins of B edge connector is lost. |
| Analysis: |
Left-hand board guides are ~1/16" out-of-alignment with edge connectors.
Long boards (M Reg, T Reg, etc.) are being twisted when inserted.
May also have to do with lack of bevel on board pin edges holding the edge-connector pins away from the board pins. |
| Solution: | Washers added at screw mounts of board guide assembly to move board guides towards front. |
| Date: | 2024 Jun |
| Procedure: | Service ROM with Machine Block constructed. |
| Date: | 2024 Jul |
| Procedure: | Leader broken on Machine (Crown) tape cassette. Patched with Tuk tape. |
| Date: | 2024 Jun |
| Symptoms: | Tape drive does not stop on reverse. |
| Analysis: | Using Machine (Crown) cassette, A65.TP1 is ~ +1.9V when in leader - not high enough. CdS light sensor is apparently drifting higher R. |
| Procedure: | Aluminum reflector added to Crown cassette for convenient fix, brings A65.TP1 up to ~ +3V. CdS sensor or light emitter should be addressed in future. |
| Serial Number: | 1205A00869 |
| 1973 (date stamps on various ICs) | |
| Date of Receipt: | 2013 Mar |
| Source: | R.F. for repair |
| State upon Receipt: | Non-functional. |
| Date: | 2013 May 28-29 |
| Procedure: |
- Various checksum errors on read. Apparently fixed by manipulation and exercising of contacts of head board.
- Writing does not work. U10 74L86 in interface has pin 4 output stuck ~0V. Input pin 6 open circuit measures ~4V while other OC inputs are ~1.4V. Replaced with 74LS32, pinout differs so pins for two gates are reordered. - Functional, occasional checksum errors on large files on 'verification' cassette. - O-rings on drive wheels swapped. Measured as 1-5/8 OD, 1-3/8 ID, 1/8-inch round. |
| Serial Number: | 1205A01570 |
| Year of Manufacture: | 1973 (date stamps on various ICs) |
| Date of Receipt: | 2013 Mar |
| Source: | R.F. for repair |
| State upon Receipt: | Non-functional. |
| Date: | 2013 May 30-31 |
| Procedure: |
- O-rings on drive wheels removed and wiped down with alcohol.
- Forward motor bearing noted to be somewhat worn or loose. Forward pulley bearing opened. - Reverse drive cylinder on motor trimmed down as it was not seated fully down the motor shaft. - Neon lamp in power switch replaced. - Loose front-door plate stuck back on with double-sided tape. - Motion is anemic, rewind button does not latch rewind. LDR leaky, will only go up to 14K in dark. LDR/lamp pair replaced with IR detector and IR LED from surplus photo-interruptor. 301 ohm limiting resistor for LED giving about 12mA LED current. Plastic mount drilled out for LED, LDR hole in tape guide drilled larger for IR detector. Tape/leader voltages at TP1 are approx. 0.0V/4.0V. Bright light gives 4.9V. - Unit will not load, searches forever or until end of files. Board swapping indicates problem is on A62. Hypothesized to be lack of FLAG indication. Board A62 powered up, static checks indicate U62-9 (7410) is bad, outputs do not go high. U62-9 replaced. - Functional, occasional checksum errors on large files on 'verification' cassette. |
| Date: | 2013 Jun 02 |
| Procedure: |
Analog read levels examined from the 3 cassette drives to sort out errors and discrepancies when reading.
Significant differences noted, best on 9830, worst on 9865-0879.
Demagnetising head on 0879 made no apparent difference.
Slight wear groove noted in heads on both 9865s. Head pressure pads in tape cassettes come in two forms: some with foam to apply the pressure and some with a metal band spring. In those with foam, notably HP cassettes, the foam is decaying and not holding the tape against the head. This was the problem; replacing the foam or substituting a band spring from a donor cassette restores reliable operation. |
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| Unit Log
HP 9830 |
bhilpert 2013 Mar |