IBM 3270 PC/G Troubleshooting Guide
.jpg)
The IBM 3270 PC/G is a 5371 system unit, based on the PC XT, driving the 5279 Color Display through the 5278 Display Attachment Unit.[1] Faults in the system board, power supply, drives and host adapter are diagnosed as on the 3270 PC. The faults below are specific to the PC/G. IBM's PC/G maintenance manual was SY33-0112.[2]
Symptoms
[edit | edit source]| Symptom | Probable cause | Action |
|---|---|---|
| No picture at all; the 5278 seems dead | The 5278 has no mains lead and takes its power from the 5279[1] | Check the 5279's power cord, outlet and switch first, then the 680 mm cable between the 5279 and 5278 |
| 44xx error | The display attachment unit and display as a pair; on the XT-based PC/G, also the display adapter card in the system unit[1] | Check the 1 m cable (P/N 1887792) and the 680 mm cable (P/N 1887778), then substitute the 5278, the 5279 and the adapter one at a time |
| Band of interference on part of the screen | A 5278 Model 1 (for the 5371) fitted to an AT-based 5373[1] | Use a Model 2 (P/N 1887745) on a 5373, a Model 1 (P/N 1887693) on a 5371 |
| 2801 at POST after a long DFCA was replaced with the short card | The Keyboard/Tablet/Mouse Adapter needs updating[1] | IBM's fix is ECA040 |
| 2858 after fitting a new DFCA | Diagnostics older than level 2.40[1] | Use customer diagnostics P/N 1887728 or advanced diagnostics P/N 1887729 at level 2.40 or later |
| Random characters from the keyboard after power-on, not every time | An early Keyboard/Tablet Adapter on some early 5371 units[1] | Such cards are about 1.5 inches shorter than full length and have no yellow wires on the solder side; replace only if it fails |
| 45xx error | IEEE-488 Interface Adapter[1] | Check the plotter cable, then the adapter |
| Other 28xx, 1xx to 18xx errors | As on the 3270 PC | See the IBM 3270 PC Troubleshooting Guide |
The 2858 entry appears in IBM's notes under the 5371 heading, where the text refers to fitting the adapter "in a 5378 System Unit"; there is no 5378 system unit, so treat the model number there as a misprint.[1]
Display and graphics
[edit | edit source]The 5278 does the graphics processing and holds the display buffer for the 5279, and emulates the PC Color/Graphics Monitor Adapter for DOS programs.[1] Its CGA emulation does not support a light pen, border colour, TV monitors, background intensity, 40 × 25 text, a block cursor on the 5279, or storage for multiple display formats. Programs that rely on them misbehave on a working machine. A standard CGA card and a standard PC keyboard are not permitted in the work station.[2]
The system board display switches must be set for a 3270 display: IBM gives the 3270 PC, PC/G and PC/GX system board settings as the same as the 5160, with positions 5 and 6 on.[1]
Mouse and tablet
[edit | edit source]Only one 5277 Mouse or one 5083 Tablet can be connected at a time, through the Keyboard/Tablet/Mouse Adapter.[1] The 5277 is optical and reads its position from a printed pad, so a missing or damaged pad stops it working.[1]
Diagnostics diskette
[edit | edit source]IBM's engineers used the PC/G Customer Diagnostic Diskette, which is kept with the Guide to Operations at the customer site.[1]
Power and capacitors
[edit | edit source]The 5371 uses the PC XT system board and power supply.[1] Check the rails against IBM's limits in the 3270 PC maintenance guide, and look for shorted tantalums as described on the IBM 3270 PC/G Capacitor Replacement Guide.
Related pages
[edit | edit source]- IBM 3270 PC/G
- IBM 3270 PC/G Maintenance Guide
- IBM 3270 PC/G Capacitor Replacement Guide
- IBM 3270 PC Troubleshooting Guide
- IBM 3270 PC/GX Troubleshooting Guide
References
[edit | edit source]- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 IBM, IBM Personal Computer Family Service Information Manual, SA38-0037-00, 1989, hosted as IBM Personal Computer Family Service Information Manual. Chapter 10, pp. 10-5 to 10-13: 5371 description, 5278 and 5279 power arrangement and cables, 3270 unique error codes, and the diagnostic tips for the PC/G, PC/GX, AT/G and AT/GX and for the 5371. Chapter 18, p. 18-34: 5278 and 5279 FRU numbers.
- ↑ 2.0 2.1 IBM, Introducing the IBM 3270 Personal Computer/G and /GX Work Stations, GA33-3141-0, May 1984, hosted as File:Introducing the IBM 3270 PC G and GX Work Stations GA33-3141-0.pdf. Related publications p. v; compatibility limits p. 100.