Jump to content

Rainbow 100+ General Maintenance

From RetroTechCollection
DEC Rainbow 100+ (Centre for Computing History)
Rainbow 100+ (Centre for Computing History)

Maintenance points specific to the Rainbow 100+ and the PC100-B: the RD51 hard disk and its controller, the H7842-D power supply and the DC fan. Everything else (environment, cover and system module removal, ROMs, the RX50 drive, the VR201 monitor and its adjustments) is the same as on the PC100-A and is covered on Rainbow 100 General Maintenance.[1]

The system unit contains a mains switching supply and the VR201 monitor a CRT. Read CRT Discharge Procedure before opening the monitor.

Power supply and fan

[edit | edit source]

The H7842-D is an H7842-A redesigned to supply more +5 V current for the hard disk. A two-wire cable on the fan bracket's 6-pin connector carries +12 V from the supply to the DC fan; the 3-pin and 4-pin connectors carry the mains through the front power switch.[2] The fan bracket assembly for the PC100-B is 70-20816-01, against 70-19572-00 for the PC100-A.[3] DEC specifies forced-air cooling of at least 40 CFM.[4]

The 115/230 V selector is below the mains connector; it slides right for 115 V and left for 230 V. DEC's warnings are the same as for the H7842-A: 230 V with the switch at 115 V damages internal components, and 115 V with the switch at 230 V leaves the computer unable to run. Before opening the supply cover, switch off, wait five minutes and check with a voltmeter that no high voltage remains.[5] The bulk voltage is 325 V DC, measured between pins 1 and 4 of L1, and fuse F1 is soldered into the power supply board.[6][7]

H7842-D outputs (DEC section 5.5.3)
Output Load range Total tolerance Ripple and noise
+5.1 V 2.5–11.5 A ±6% 50 mV p-p
+12.2 V 0.6–6.7 A ±6% 75 mV p-p
−12 V 0–0.15 A ±7% 120 mV p-p

[4]

The output table in chapter 5 of DEC's addendum is the same as the H7842-A's, although chapter 1 of the addendum gives a −12 V maximum of 388 mA.[4][8] For the circuit description and Rob Jarratt's H7842 repairs, see DECmate II Power Supply Service.

Hard disk

[edit | edit source]

The RD51 draws 3.5 A from +12 V while spinning up and 1.6 A once running.[9] DEC describes it as a delicate precision instrument that must not be dropped or bumped, and supplied a packing container for it (99-90045-01).[10][11]

Removing the drive

[edit | edit source]
  1. Switch off, unplug the mains and all cables, and take the cover off.
  2. Pull the ground clip of the hard disk cable off the ground lug on the power supply.
  3. Press the latch in front of the drive and slide it partly forward.
  4. Unplug the 4-wire power cable from the back of the drive. Pull the signal cable straight off its two connectors, not at an angle.
  5. Slide the drive out and put it in its original packing for transport.[10]

DEC suggests trying another drive cable before replacing a drive.[10] When refitting, push the drive home without slamming it, refit the ground clip, and lay the cable flat across the top of the diskette drive so that it clears the cover.[12]

Removing the controller

[edit | edit source]

The hard disk controller (54-16019) plugs into J4 and J5 on the system module, the same connectors as the extended communications option.[13] When taking the system module out, unplug the hard disk cable from the system module before the power cable, and leave its ground clip attached.[14] The controller sits on a spacer (74-29164-01), which DEC says to keep and refit.[15][11]

See Hard Drive Maintenance and Repair for general hard disk care.

Routine checks

[edit | edit source]
  1. Check the voltage selector before the first power-up, and look over the H7842-D for bulging or leaking capacitors.
  2. Switch on. A PC100-B sizes its memory and can boot itself, so check the screen and the rear LEDs as for the PC100-A (see Rainbow 100 Troubleshooting Guide).[16]
  3. Listen for the DC fan; on this model it runs from the supply's +12 V output.[2]
  4. Run the hard disk diagnostic from the diagnostic diskette (test 16, installed from the option's own diskette) or from the Rainbow Hard Disk Utility Program diskette.[17]
[edit | edit source]

References

[edit | edit source]
  1. ↑ Digital Equipment Corporation, Rainbow Technical Manual Addendum for Models PC100-A, PC100-B, and Rainbow 100+, EK-RB100-TM-001, December 1984, pp. 1-1 to 1-3 (File:Rainbow Technical Manual Addendum PC100-A PC100-B and 100+ (EK-RB100-TM-001).pdf). Models and their units.
  2. ↑ 2.0 2.1 DEC, EK-RB100-TM-001, p. 5-1, sections 5.1 and 5.2. H7842-D, fan bracket and connections.
  3. ↑ DEC, User's Service Guide, EK-P100E-SV-001, p. 124, Table B-1. Fan bracket assemblies.
  4. ↑ 4.0 4.1 4.2 DEC, EK-RB100-TM-001, pp. 5-7 to 5-8, section 5.5. H7842-D specifications.
  5. ↑ DEC, EK-RB100-TM-001, p. 5-2. AC selector switch and warnings.
  6. ↑ DEC, EK-RB100-TM-001, p. 5-4, section 5.3. Fuse F1 soldered into the board; 325 V bus.
  7. ↑ DEC, EK-RB100-TM-001, p. 5-5, section 5.4.1. 325 V measured between pins 1 and 4 of L1.
  8. ↑ DEC, EK-RB100-TM-001, pp. 1-6 to 1-7. Power supply summary, −12 V at 388 mA.
  9. ↑ DEC, EK-RB100-TM-001, pp. 1-9 to 1-10, section 1.3.5. RD51 input power.
  10. ↑ 10.0 10.1 10.2 DEC, User's Service Guide, EK-P100E-SV-001, pp. 38 to 39. Hard disk drive removal and caution.
  11. ↑ 11.0 11.1 DEC, User's Service Guide, EK-P100E-SV-001, p. 125, Table B-1. Hard disk controller spacer and RD51 packaging container.
  12. ↑ DEC, User's Service Guide, EK-P100E-SV-001, pp. 48 to 49. Hard disk drive installation.
  13. ↑ DEC, EK-RB100-TM-001, p. 3-4, Figure 3-2. J4 and J5 for the extended communications or hard disk controller option.
  14. ↑ Digital Equipment Corporation, User's Service Guide (Rainbow), EK-P100E-SV-001, April 1985, p. 18 (File:Rainbow User's Service Guide (EK-P100E-SV-001).pdf). Hard disk cable before power cable.
  15. ↑ DEC, User's Service Guide, EK-P100E-SV-001, p. 24. Hard disk controller board removal and replacement.
  16. ↑ DEC, EK-RB100-TM-001, p. 1-4, Table 1-1. Automatic memory sizing and bootstrap.
  17. ↑ DEC, User's Service Guide, EK-P100E-SV-001, pp. 100 to 101. Diagnostic tests 14 to 16 and the Winchester option test.
Retrieved from "https://retrotechwiki.com/index.php?title=Rainbow_100%2B_General_Maintenance&oldid=21582"