MicroVAX 3100 Troubleshooting Guide
.png)
A MicroVAX 3100 tests itself at power-up and reports on the console terminal: each device is numbered, a single question mark marks status information and a double question mark a hard error. Eight diagnostic LEDs on the rear panel also light during power-up.[1][2] DEC's owner's manual for the Model 10 and 20, and its troubleshooting manual for the Model 85 and 95, give the checks below. If the machine shows little or no sign of life, start with the power supply: restorers have found leaking capacitors in the H7821 and H7822 supplies.[3]
No power, no display
[edit | edit source]| Symptom | Possible cause | Action |
|---|---|---|
| Fan off, power light off | No mains; faulty cord or outlet; overload protection tripped by a line disturbance (85/95); faulty supply | Check cord and outlet; switch off for 10 seconds and on again; then the supply |
| No power-up display after 20 seconds | Terminal cable, terminal fuse or terminal settings (9600 baud, 8 bits, no parity); console on the wrong port | Check the terminal; on the 85/95 the console is MMJ port 3 |
| No display, terminal good | Break Enable switch in the wrong position | Down for a console on MMJ port 1, up for port 3; the switch is read only at power-up |
[4][5] Peter Coghlan's stored MicroVAX 3100 would only flash its diagnostic LEDs briefly and twitch its fans; the cause was five leaking 1800 µF capacitors in the H7821 supply.[3] Rob Jarratt's Model 95 ran but kept losing memory modules, with the supply's 5.1 V output reading 5.3 V.[6] See MicroVAX 3100 Power Supply Service.
Power-up messages (Model 10 and 20)
[edit | edit source]| Identifier | Device |
|---|---|
| F | Reserved |
| E | System clock |
| D | Non-volatile RAM |
| C | Serial line controller |
| B | Memory |
| A | Memory management unit |
| 9 | Floating-point unit |
| 8 | Interval timer |
| 7 | SCSI-A bus controller |
| 6 | SCSI-B bus controller |
| 5 | Interrupt controller and Ethernet ID ROM |
| 4 | DSH32-B asynchronous lines |
| 3 | DSH32-B synchronous lines |
| 2 | Reserved |
[1] DEC's examples of status and error lines:[1]
? E 0040 0000.0005: system clock not set. Set it from the operating system.? D 0050 0000.0005: low battery. Run the system for about 17 hours to recharge it.?? 1 00C0 0000.7004: Ethernet present but no cable, no loopback on the standard port, no terminator on the ThinWire port, Ethernet switch in the wrong position, or a faulty cable.
An asterisk means a ROM was found on an option but there is no test code for it.[1] Single question marks next to 7 or 6 (the SCSI controllers) with the system working normally can be ignored unless they persist.[1] If no question marks or asterisks appear but the operating system does not start, check the default boot settings and that the default recovery action is not set to halt.[4]
Self-tests and configuration display
[edit | edit source]Press the halt button on the rear with a pointed object to enter console mode, then type TEST and an identifier from the table, or a range such as TEST F 7. A failing test prints FAIL. TEST 50 shows the configuration, the Ethernet address, ROM revisions and each device's status, which DEC asks you to have ready when calling for service.[7] Note which of the eight rear LEDs are lit as well.[2]
Model 85 and 95
[edit | edit source]The Model 85 (KA55) and 95 (KA51) count down from 74 at power-up. A failure prints the test and subtest number, an error type and the name of the diagnostic listing, followed by register dumps and "Normal operation not possible."[8] Memory faults are reported per SIMM set: SIMMs fit in sets of four (0A to 0D, 1E to 1H), all four of a set must be the same type, and a missing or mismatched SIMM gives an error for the whole set. SHOW MEMORY is DEC's most useful command for finding a bad SIMM.[8][9] Jarratt's Model 95 reported "Test_Subtest_40_06" with 32,768 bad pages on SIMM set 1 while VMS reported the memory as normal.[6] Before calling DEC, the 85/95 manual asks for the error messages, the status LED display on the rear and the steps already taken.[10]
Related pages
[edit | edit source]- MicroVAX 3100
- MicroVAX 3100 Maintenance Guide
- MicroVAX 3100 Power Supply Service
- MicroVAX 3100 Documentation
- MicroVAX II Troubleshooting Guide
References
[edit | edit source]- ↑ 1.0 1.1 1.2 1.3 1.4 DEC, EK-A0371-OM-002, section 6.2 and Table 6-2, pp. 6-6 to 6-8.
- ↑ 2.0 2.1 DEC, EK-A0371-OM-002, section 6.10, pp. 6-21 to 6-22.
- ↑ 3.0 3.1 Peter Coghlan, "H7821 power supply in MicroVAX 3100, SCSI disk enclosures and others", cctalk mailing list, 31 January 2020, mail-archive.com.
- ↑ 4.0 4.1 Digital Equipment Corporation, MicroVAX 3100 and VAXserver 3100 Owner's Manual, EK-A0371-OM-002, August 1989, section 6.1 and Table 6-1, pp. 6-2 to 6-6 (File:MicroVAX 3100 and VAXserver 3100 Owner's Manual (EK-A0371-OM-002).pdf).
- ↑ Digital Equipment Corporation, MicroVAX 3100 Model 85/95 Troubleshooting and Diagnostic Information, EK-A0719-TM.B01, June 1994, Table 1-1 (File:MicroVAX 3100 Model 85-95 Troubleshooting and Diagnostic Information (EK-A0719-TM).pdf).
- ↑ 6.0 6.1 Rob Jarratt, "MicroVAX 3100 Model 95 Power Supply", Rob's Old Computers, 10 May 2020, robs-old-computers.com.
- ↑ DEC, EK-A0371-OM-002, sections 6.3 and 6.4, pp. 6-8 to 6-11.
- ↑ 8.0 8.1 DEC, EK-A0719-TM.B01, section 1.3.3, Examples 1-1 and 1-2.
- ↑ DEC, EK-A0719-TM.B01, section 1.3.1, memory display and SHOW MEMORY.
- ↑ DEC, EK-A0719-TM.B01, section 1.4 and Figure 1-2.