Jump to content

TRS-80 PC-2 General Maintenance

From RetroTechCollection
Radio Shack TRS-80 PC-2 Pocket Computer
A TRS-80 PC-2 (Oldlaptop321, CC BY-SA 3.0).

Care of the TRS-80 PC-2 (catalogue number 26-3601) and its 26-3605 printer and cassette interface. The PC-2 is a Sharp PC-1500 and the 26-3605 a Sharp CE-150,[1] so routine care of the computer itself (cells, cleaning, keyboard, display, the module slot and the side connector) is covered on Sharp PC-1500 General Maintenance and is not repeated here. What follows is what Radio Shack's own service manual adds, in particular about the plotter mechanism of the 26-3605.[2] Faults are covered on TRS-80 PC-2 Troubleshooting Guide.

The computer

[edit | edit source]
  • The PC-2 runs from four AA cells for about 75 hours, or from a DC adaptor.[3] When docked in a charged 26-3605 it runs from the interface's cells.[3]
  • Inside, the keyboard board is joined to the main board by a flexible printed cable, soldered at the keyboard end and held by a crimp fitting at the main board end. Radio Shack's procedure for replacing it is on TRS-80 PC-2 Troubleshooting Guide.[4]
  • The supply voltages and the LCD voltage are set with two trimmers on the regulator circuit; see TRS-80 PC-2 Troubleshooting Guide before touching them.[5]

The 26-3605 printer and cassette interface

[edit | edit source]

The interface has its own NiCd pack of five AA-size cells, charged from the AC adaptor, and Radio Shack rated it at about 1,100 lines of printing per charge.[6] Kaiser warns that these packs fail with age and have to be replaced every so often.[1] The pack is Radio Shack part ACS-0093 (Sharp UBATN2135CC01).[7]

Handling the plotter

[edit | edit source]

Radio Shack's handling precautions for the printer mechanism:[8]

  • Carry the printer mechanism only in the directions the manual shows; it may also be held by the upper face of the motor cover and paper guide, without pressing hard.
  • Do not touch the slider unit except to take out a pen, and never push it in its direction of rotation.
  • Do not touch the drive wire, or the pulley may come off. Do not touch the colour-change click; if it is bent, colours will no longer change.
  • Do not touch any shaft with bare hands, or the pen return spring. Touch the rotary holder only with the slider at the right-hand end of the frame and a pen fitted.
  • Keep magnets, magnetic powder and electromagnets away from the permanent magnet of the colour position detector. The electromagnet unit itself contains a strong rare-earth magnet.
  • Do not drop or knock the pens. When a pen's ink runs out, hold it by the tail plug and shake it.

Cleaning

[edit | edit source]

Radio Shack advises cleaning the printer after use, or at most every three months:[8]

  1. Vacuum out paper dust and dirt.
  2. Remove stains with alcohol or benzine. Do not use thinners, trichloroethylene or ketone solvents, which can damage the plastic parts.
  3. Grease any point that is dry, using only the specified lubricant (below).

Lubrication

[edit | edit source]

The manual specifies two oils: G488 (Sharp part UKOG-0108CSZZ) and CRC 5-56. When the mechanism is taken apart, clean the parts and oil them as follows.[9]

26-3605 oiling points
Oil Points
G488 Paper holding roller support plates (left and right) where they meet the side plates; the four sliding points between the paper holding rollers and their shaft; rubber roller unit shaft and plain washer; plain washer and side plate; ejection lever shaft and slide plate; ejection roller and slider set; teeth of the X and Y idle gears; holder stopper and holding plate; electromagnet actuator shaft
CRC 5-56 Slider shafts A and B

Screw locking

[edit | edit source]

After reassembly, the manual calls for screw-lock on the set-screws of the X and Y motors, the bobbin gear and slider wire clamps, the electromagnet, the reed switch and the colour-change click, covering more than a quarter of each screw head but keeping the recess clear. The rubber roller bearing is fixed to the side plate with cyanoacrylate adhesive.[10]

Tools

[edit | edit source]

The manual's tool list for printer repairs is: precision Phillips screwdrivers sizes 4 and 5 and a size 5 flat blade, "ET" holders in three sizes, radio pliers, tweezers and a soldering iron.[11]

Capacitors

[edit | edit source]

The PC-2 has two types of electrolytic capacitor and the 26-3605 two more. See TRS-80 PC-2 Capacitor Replacement Guide.

[edit | edit source]

References

[edit | edit source]
  1. ↑ 1.0 1.1 Cameron Kaiser, "Tandy Radio Shack Pocket Computer PC-2", Floodgap Retrobits, Tandy! Pocket! Mania! (retrieved 2026-10-21). Sharp equivalents, NiCd cells in the 26-3605, plotter gear failures. Community source.
  2. ↑ Radio Shack, Service Manual: TRS-80 Pocket Computer, Printer and Cassette Interface, catalogue numbers 26-3601 and 26-3605. Hosted here as File:Radio Shack TRS-80 PC-2 Pocket Computer and Printer Cassette Interface Service Manual (26-3601, 26-3605).pdf (see TRS-80 PC-2 Documentation). Page numbers are the printed ones.
  3. ↑ 3.0 3.1 Matthew Reed, "The TRS-80 Pocket Computer 2", TRS-80.org (retrieved 2026-10-21). Specifications, battery life, accessories and the 26-3605.
  4. ↑ Service Manual, pp. 17-18, "5. Servicing": all-reset procedure and replacing the flexible printed cable.
  5. ↑ Service Manual, p. 16, "6) Power supply circuit".
  6. ↑ Service Manual, pp. 28-29, specifications and system block diagram of the 26-3605.
  7. ↑ Service Manual, p. 35, parts list for the 26-3605.
  8. ↑ 8.0 8.1 Service Manual, p. 54, "4. Repair and Maintenance": handling precautions and cleaning.
  9. ↑ Service Manual, p. 64, "5. Oiling Standard".
  10. ↑ Service Manual, p. 65, "6. Adhesion Standard".
  11. ↑ Service Manual, p. 55, "3. Repairs": repair procedure and repair tools.


Retrieved from "https://retrotechwiki.com/index.php?title=TRS-80_PC-2_General_Maintenance&oldid=29009"