TRS-80 PC-7 General Maintenance
.jpg)
The TRS-80 PC-7 runs from two CR2032 lithium cells and has no backup cell and no way to save programs, so changing the cells clears its memory. The other weak point is the folding case: the join between the two halves and the ribbon cable that crosses it.[1] No Tandy or Casio manual for the PC-7 is available, so the steps below come from the PC-7's own construction as Kaiser describes it and from the PC-4 and PC-6 manuals where noted.
Cells
[edit | edit source]The PC-7 takes two CR2032 cells.[2] It has no memory backup cell and no port for a cassette interface, so anything in memory is lost when the cells come out.[1] Write programs down on paper before a cell change if you want to keep them.
On the PC-6, the nearest documented relative, Tandy's remedy for poor battery contact is to clean the cell and spring and lift the spring; the same check is worth making on a PC-7 that will not start.[3] For leakage, see Battery Explosion, Capacitor or Corrosion Damage.
Hinge, join and ribbon cable
[edit | edit source]Kaiser reports that all but his new-old-stock PC-7 showed flex strain at the join between the two halves, and that some had torn open there, exposing the ribbon cable, which the twisted case strains further.[1]
- Open and close the lid by both halves, not by one corner, so that the join is not twisted.
- Inspect the join for cracks before opening the case. Where Kaiser found the join torn, the ribbon cable beneath it was exposed and strained.[1]
- The letter keys are on the other half from the display and the numeric keys, so the ribbon cable carries them across the join. If letter keys fail, or work only with the lid at some angles, suspect the cable.
Keyboard
[edit | edit source]The letters are on a membrane panel in the lid, in alphabetical order, and the numbers and functions are on moulded keys.[1][4] On the PC-6, whose letters are on the same kind of membrane, Tandy's remedy for a dead key is to clean the contact pads on the board and the key contact rubber.[3]
Opening the case
[edit | edit source]No PC-7 disassembly procedure is available from the Floodgap archive or the Internet Archive. Work on an earthed mat, photograph each layer as it comes apart, and keep the two halves supported so that the ribbon cable across the join is not pulled.
Related pages
[edit | edit source]- TRS-80 PC-7
- TRS-80 PC-7 Troubleshooting Guide
- TRS-80 PC-7 Capacitor Replacement Guide
- TRS-80 PC-6 General Maintenance – the nearest documented relative
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 Cameron Kaiser, "Tandy Radio Shack Pocket Computer PC-4 and Tandy Pocket Scientific Computer PC-5, PC-6, PC-7", Floodgap Retrobits, Tandy! Pocket! Mania!. Retrieved 2026-10-21. PC-7 section: no battery backup; no expansion port, so no tape or printer; the flip case's flex strain at the join, torn cases exposing the ribbon cable, which is stressed by the case distortion; the membrane alphabetic keyboard.
- ↑ Pocket Museum, "The Tandy PC-7 computer (26-3673)". Retrieved 2026-10-21. Power: two CR2032 cells; no extensions.
- ↑ 3.0 3.1 Tandy, Service Manual: Pocket Scientific Computer PC-6. Hosted as File:Tandy PC-6 Pocket Scientific Computer Service Manual (26-3672).pdf. Troubleshooting guide p. 10: poor battery contact (clean the cell and spring, lift the spring) and poor key contact (clean the contact pad on the board and the key contact rubber).
- ↑ Wikipedia, "Tandy Pocket Computer", section "Purpose". Retrieved 2026-10-21. The PC-7's rectangular, alphabetically ordered keyboard.