DECstation 5000 General Maintenance
Routine care, opening and service procedures for the DECstation 5000 Model 200 series, from DEC's maintenance guides EK-370AA-MG-002 (Model 200) and EK-PM38C-MG-002 (Models 200, 240 and 260) and the Model 200 operator's guide.[1][2][3] The machines are now over 30 years old. The parts that wear out are the power supply and its three fans; the system module itself has no user-serviceable parts apart from the memory, the Ethernet address chip and the clear-NVR jumper.
Environment
[edit | edit source]DEC's operating limits for the Model 200 system unit:[4]
| Operating | Not operating | |
|---|---|---|
| Temperature | 10 to 40 °C | −40 to 66 °C |
| Rate of change | 11 °C per hour maximum | – |
| Relative humidity | 20% to 80%, non-condensing | 10% to 95%, non-condensing |
| Maximum wet bulb | 28 °C | 46 °C (packaged) |
| Altitude | 2400 m at 36 °C | 4900 m at 36 °C |
A machine brought in from a cold store should warm to room temperature before it is switched on; DEC's limit on temperature change is 11 °C an hour.[4]
Opening the system unit
[edit | edit source]Use an antistatic wrist strap clipped to an antistatic mat, and lay modules on the mat.[5] DEC's procedure for the cover:[5]
- Switch off and disconnect the power cord.
- Loosen the captive screw that holds the cover.
- Facing the front, grip both sides of the cover, pull it towards you until it comes free, then lift it away.
- To refit, set the cover on the chassis about 2 inches (50 mm) short of the back, slide it back until it clicks into place and tighten the screw.
The front cover plate comes off after the cover: loosen its two captive screws, tilt the top down and lift it away.[5]
System module
[edit | edit source]The system module and its metal chassis are one replaceable unit. DEC's warnings are never to remove the module from the chassis, which breaks its FCC emissions compliance, and never to touch the heat sinks on the module, which are fragile.[6]
The Ethernet station address is held in a socketed ESAR chip. When a system module is changed, move the ESAR chip to the new module so the machine keeps its address; fit it with the notched end towards the power supply and take care not to bend the pins.[6]
Memory
[edit | edit source]The Model 200 takes up to fifteen 8 MB memory modules (MS02-AA), held down by a retaining bar.[6][7] The Model 200 series guide adds 32 MB modules (MS02-CA) and a 1 MB NVRAM module (54-20948-01). Fill slots from slot 0, nearest the back of the unit, use one module size throughout, and keep slot 14 for the NVRAM module if one is fitted.[8] Loose modules are the first thing DEC checks after a memory error; reseat them before replacing anything.[6]
Power supply and fans
[edit | edit source]The supply provides 244 W DC and its three fans draw air through the whole system unit. A green LED on the front of the supply shows that it is working.[6][9] DEC fitted it under two part numbers, 30-32506-01 and H7878A, which it lists as functionally identical.[9]
Keep the fan inlets and the vents clear of dust, and check all three fans turn whenever the cover is off. A stopped fan leads to the misc/pstemp overheat message.[6] The fan assembly is a removable panel held to the supply base by eight screws, with one power cable to the supply.[6]
To remove the supply:[6]
- Switch off, unplug the power cord, and remove the cover and front plate.
- Disconnect the system module power cords: DEC's figure shows two 5 V cords and one 12 V cord.
- Loosen the two captive Allen screws and pull the supply away from the back of the unit and out of the chassis.
- To refit, make sure the supply switch is off (0 pressed), set it in the chassis with the switch towards the back, tighten the two Allen screws and reconnect the cords.
The supply is a switch-mode unit with electrolytic capacitors that have now aged; see DECstation 5000 Capacitor Replacement Guide for the capacitors replaced in a repaired H7878, and Capacitor Failure Symptoms for what failure looks like.[10] Warning: the input capacitors charge to over 300 V DC from the mains.[10]
Console settings and the clock battery
[edit | edit source]The console keeps its environment variables (boot device, halt action, console device, password) in the 50 bytes of battery-backed RAM in the DS1287 real-time clock.[11] Write the settings down with printenv before any work. Console status code 0439 reports that the clock values indicate a dead battery.[12]
To clear a forgotten password, switch off, fit the clear-NVR jumper (DEC part 12-14314-00) over the two-pin clear-NVR header on the system module, switch on and wait for the console prompt, switch off, remove the jumper and switch on again. Then set the environment variables again with setenv.[5][7]
Keyboard and mouse
[edit | edit source]The Model 200 uses the LK201 keyboard and VSXXX-AA mouse on a keyboard-mouse cable to the DB15 connector at the rear.[13] DEC's mouse cleaning: turn the mouse over, turn the round plate to the left to release it, take out the ball, wash it in lukewarm water with mild soap if needed, dry it with a lint-free cloth and refit it. DEC warns that organic solvents such as toluene damage the ball's rubber coating.[14]
Spare part numbers
[edit | edit source]| Item | Part number |
|---|---|
| System module and chassis | 70-26722-02 |
| Power supply assembly | 30-32506-01 |
| 8 MB memory module | MS02-AA |
| System unit cover | 70-27056-01 |
| Front cover plate | 70-27053-01 |
| Clear-NVR jumper | 12-14314-00 |
| Communications loopback connector | 12-15336-06 |
| ThinWire terminator | 12-26318-01 |
Related pages
[edit | edit source]- DECstation 5000
- DECstation 5000 Troubleshooting Guide
- DECstation 5000 Capacitor Replacement Guide
- DECstation 5000 Documentation
- Recommended Tools
References
[edit | edit source]- ↑ Digital Equipment Corporation, DECstation 5000/DECsystem 5000 Model 200 Maintenance Guide, EK-370AA-MG-002, October 1990 (File:DECstation 5000 Model 200 Maintenance Guide (EK-370AA-MG-002).pdf).
- ↑ Digital Equipment Corporation, DECstation/DECsystem 5000 Model 200 Series Maintenance Guide, EK-PM38C-MG-002, April 1993 (File:DECstation 5000 Model 200 Series Maintenance Guide (EK-PM38C-MG-002).pdf).
- ↑ Digital Equipment Corporation, DECstation 5000 Model 200 Hardware Operator's Guide, EK-366AA-OG-002, October 1990 (File:DECstation 5000 Model 200 Hardware Operator's Guide (EK-366AA-OG-002).pdf).
- ↑ 4.0 4.1 4.2 DEC, EK-370AA-MG-002, pp. A-2 to A-3, Tables A-3 and A-4. Operating and non-operating conditions.
- ↑ 5.0 5.1 5.2 5.3 DEC, EK-370AA-MG-002, pp. 2-2, 2-6 to 2-8 and 2-20 to 2-22. Antistatic kit, cover and front plate removal, clear-NVR jumper.
- ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 DEC, EK-370AA-MG-002, pp. 5-2 to 5-12 and 5-20 to 5-26. System module and chassis warnings, ESAR chip, memory modules, power supply, fan assembly and removal.
- ↑ 7.0 7.1 7.2 DEC, EK-370AA-MG-002, pp. B-1 to B-3, Tables B-1 and B-2. Part numbers.
- ↑ DEC, EK-PM38C-MG-002, pp. 1-14 to 1-15. Memory module types, slot order, NVRAM module in slot 14.
- ↑ 9.0 9.1 DEC, EK-PM38C-MG-002, p. 5-20. Power supply rating, fans, LED and the part numbers 30-32506-01 and H7878A.
- ↑ 10.0 10.1 Rob Jarratt, "DECstation 5000 Model 240 H7878 Possible Fault Found" (28 August 2017) and "PSU Fixed" (1 October 2017), Rob's Old Computers, robs-old-computers.com.
- ↑ Digital Equipment Corporation, DS5000/200 KN02 System Module Functional Specification, 1990, section 4.5.3 (File:DECstation 5000 Model 200 KN02 System Module Functional Specification.pdf). DS1287 clock and 50-byte battery-backed RAM.
- ↑ DEC, EK-370AA-MG-002, appendix G, Table G-2, p. G-5. Minor console status code 0439.
- ↑ DEC, EK-370AA-MG-002, p. 1-10. Keyboard and mouse.
- ↑ DEC, EK-366AA-OG-002, pp. 2-23 to 2-24. Cleaning the mouse.