Amstrad 6128 Plus Troubleshooting Guide
The Amstrad 6128 Plus shares its main board, cartridge slot, keyboard and monitors with the Amstrad 464 Plus. Start-up, cartridge, monitor, sound, keyboard and software-compatibility faults are diagnosed the same way on both and are covered in the Amstrad 464 Plus Troubleshooting Guide. The sections below cover the disc drive and the differences. Amstrad's service manual has no fault-finding charts for the Plus range and refers engineers to the RP11 diagnostic ROM cartridge.[1]
Power and start-up
[edit | edit source]The 6128 Plus has one supply, 5 V from the monitor at J104; there is no 12 V lead to check.[1] Amstrad sets the monitors' 5 V output to 4.80 V under a 2.4 A load, and the MM12 page shows the output dropping to 0 V at 3.6 ±0.4 A.[1] If the drive light, the power LED and the screen are all dead, measure the 5 V with the computer's lead unplugged and then plugged in.
A working machine with its cartridge shows "Amstrad Microcomputer (v4)" and the Amstrad and Locomotive Software copyright line.[2] Without a cartridge it will not start, whatever disc is in the drive.[3]
Disc faults
[edit | edit source]| Symptom | Probable cause | Action |
|---|---|---|
| Disc corrupted after power-up or power-down | Disc left in the drive while switching | Amstrad's instructions say never to switch on or off with a disc in the drive. Restore from a back-up |
| Read errors that come and go | Drive placed directly in front of the monitor | Move the computer so the drive section is to the right of the monitor |
| Drive B lamp lit all the time | Normal | The second drive's lamp stays lit and goes out while drive A is in use |
| Errors on every disc | Dirty head, cable, drive | Clean the head; check the drive cable and its connector; try the drive in another 6128 Plus |
| Errors on one disc only | The disc | Copy what can be read to a good disc |
The handling rules and the lamp behaviour are from Amstrad's user instructions.[2] The drive is an EME-157 (FDD201) and the disc controller is a Z765APS (IC104), with IC103 (SED9420CAC) and IC105–IC107 in the disc circuit on the main board.[1] Amstrad's service manual gives no mechanism test points or alignment figures for the EME-157; the flow charts and alignment checks Amstrad published for the earlier CPC drives are in the Amstrad CPC 6128 Troubleshooting Guide.
AMSDOS error messages (disc missing, read fail, write protected and so on) are the same as on the CPC; the table is in the CPC 664 Troubleshooting Guide.
No cassette
[edit | edit source]The 6128 Plus has no cassette socket, so tape software cannot be loaded at all; this is by design.[4][3]
Other faults
[edit | edit source]- Video, sound, keyboard and cartridge faults: see the Amstrad 464 Plus Troubleshooting Guide; the luminance adjustment on the 6128 Plus is the same VR101 setting of 1.65 V at pin 3 of J102.[1]
- Capacitors: see the Amstrad 6128 Plus Capacitor Replacement Guide and Capacitor Failure Symptoms.
Related pages
[edit | edit source]- Amstrad 6128 Plus · Amstrad 6128 Plus Maintenance Guide · Amstrad 6128 Plus Capacitor Replacement Guide
- Amstrad 464 Plus Troubleshooting Guide · Amstrad CPC 6128 Troubleshooting Guide
- Floppy Drive Repair · CRT Discharge Procedure
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 Amstrad plc, 464 PLUS Home Computer / 6128 PLUS Home Computer / GX4000 Games Console / MM 12 Monochrome Monitor / CM 14 Colour Monitor Service Manual. Described at Amstrad 464 Plus / 6128 Plus / GX4000 Service Manual. Note to engineers p. 2; 6128 Plus specification and adjustment p. 15; electrical parts list p. 22; MM12 adjustments p. 37; CM14 adjustments p. 44.
- ↑ 2.0 2.1 Amstrad plc, 464 Plus & 6128 Plus User Instructions (1990), "Installation Notes", "Special Disc Operation Notes (6128)" and chapter 1 pp. 3 and 14. Scan at archive.org. Retrieved 2026-10-01.
- ↑ 3.0 3.1 Wikipedia, "Amstrad CPC", section "464 plus, 6128 plus". Retrieved 2026-10-01. No on-board ROM; firmware on the supplied cartridge.
- ↑ Stuart Anderton, "Console and CPC Pluses take 8-bits into the '90s", New Computer Express no. 93 (August 1990). Transcribed at CPCrulez. Retrieved 2026-10-01.