Josh: Deep technical RS/6000 page rewrite with verified sources, embedded images, full cap lists

2026-05-22T10:52:31Z

Deep technical RS/6000 page rewrite with verified sources, embedded images, full cap lists

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This guide documents preventive maintenance for the '''[[IBM RS/6000]]''' family — IBM's POWER / PowerPC / POWER3 / RS64 RISC UNIX workstation and server line, machine types '''7011 / 7012 / 7013 / 7015 / 7020 / 7025 / 7026 / 7043 / 7044 / 7248'''. Procedures are common to the family where possible; submodel-specific procedures are called out where they differ.

== Safety Warning ==

All RS/6000 PSUs contain mains-rectified bulk capacitors that hold a lethal charge after power-off. Before any work inside any PSU shell:

# Power off and unplug the mains lead.
# Wait at least 30 seconds.
# Discharge the bulk capacitor through a 1 kΩ / 5 W resistor.
# Verify with a multimeter.

Rack-class RS/6000s (7015, 7026 H-series) may carry dual or redundant PSUs and may also be wired to '''−48 V DC''' instead of mains (especially R24 frames in telco service).<ref>IBM, ''RS/6000 7015 R-Series Installation and Service Guide'' (manualslib summary)</ref> Confirm the input topology of the specific system in front of you before any service work.

== Identifying Your RS/6000 ==

The machine type and submodel are printed on the rear-panel label (e.g. "Type 7012-320", "Type 7043-150 — 43P-150"). The machine type maps to a service guide:

{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''RS/6000 service-guide mapping'''
! Machine type !! IBM service guide
|-
| 7011, 7012, 7013, 7015 || SA38-0531 series (POWER1/POWER2 era)
|-
| 7020 / 7007-N40 || N40-specific HMR (rare)
|-
| 7025 (F30/F40/F50/F80) || SA38-0532 series + Redbook SG24-5143
|-
| 7026 (H10/H50/H70/H80) || SA38-0535 series + Redbook SG24-5143
|-
| 7043 (140 / 150 / 240 / 260) || SA38-0512 series + Redbook SG24-5144
|-
| 7044 (170 / 270) || SA38-0538 series
|-
| 7248 (100 / 120 / 133) || IBM 7248 HOWTO + per-board reference
|}

The machine-type prefix also tells you the era:

* '''70xx''' — Micro Channel POWER1/POWER2 (1990–1996).
* '''7248''' — PReP / Carolina board (1995–1997).
* '''7025 / 7026 / 7043 / 7044''' — CHRP / PCI / Open Firmware (1996–2000).

== Opening the System ==

=== 7011 (pizza-box desktop) ===

# Power off, unplug, discharge PSU.
# Loosen the two thumbscrews at the rear top.
# Slide the cover back ~10 mm and lift off.
# The planar is on the chassis floor; PSU on the left; drive cage at the front.

=== 7012 / 7013 (deskside) ===

# Power off, unplug, discharge.
# Open the rear access panel (two captive screws).
# The CPU MCM card and memory cards mount in a vertical riser at the rear.
# Drive cage runs vertically up the front.
# PSU is at the top or rear, depending on submodel.

The MCM module on POWER2 7012-39H / 397 is large, heavy and surrounded by heatsink mass. '''Do not''' lift the MCM out unless you have the IBM extraction tool — the module pins are fragile and the seating force is high.

=== 7015 (rack) ===

Standard 19" rack handling rules. CPU drawer typically slides out on chassis rails; ground yourself before any work; never disconnect rear power without locking the rack rails first.

=== 7025 / 7026 / 7043 / 7044 (PCI tower / rack) ===

# Power off, unplug, discharge.
# Remove side panel (single thumbscrew or latch on most submodels).
# Planar mounts horizontally; PSU at top or top-rear; drives stacked vertically.
# CPU and memory cards on '''carrier cards''' that plug vertically into the planar.

=== 7248 (Carolina PReP) ===

# Power off, unplug, discharge.
# Remove the cover (two screws at the rear).
# Carolina motherboard is in the bottom of the chassis. ISA cards on the left riser; PCI cards on the right.

== Inspecting the Planar ==

The Micro Channel era 7012 / 7013 planars carry '''surface-mount aluminium electrolytic''' capacitors of the same vintage and chemistry as the [[IBM PS/2 Model 70]] / [[IBM PS/2 Model 80|80]]. They leak. Inspect every SMD electrolytic on the planar before any other work — see [[IBM RS/6000 Capacitor Replacement Guide]] for the full procedure.

Later RS/6000 planars (7025 / 7026 / 7043 / 7044) carry through-hole and SMD tantalum decoupling plus through-hole aluminium electrolytics near the PSU input. These age more slowly than the PS/2-era SMD aluminium electrolytics but still warrant inspection.

== Regular Cleaning ==

* Soft brush and low-pressure compressed air for the planar, the riser, PCI cards, the drive cage and the PSU vents.
* Hold any fan blades by hand if using compressed air.
* Clean SCSI ribbon cable connectors and edge connectors. Original IBM SCSI cables age and develop intermittent contact in the IDC connectors.
* Clean MCA card edge fingers (POWER1/POWER2 era) with a soft eraser or deoxidising contact cleaner.
* Inspect the planar for any signs of leaked electrolyte around SMD or through-hole aluminium electrolytics.

== PSU Voltage Checks ==

Probe the PSU output rails with a multimeter while the system is powered on. RS/6000 PSUs supply the standard ATX-like rails plus, in many cases, a separate +3.3 V rail for the CPU MCM:

{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''Typical RS/6000 PSU rail tolerances'''
! Rail !! Acceptable range !! Notes
|-
| +5 V || +4.75 V to +5.25 V || I/O logic
|-
| +12 V || +11.4 V to +12.6 V || Drive motors
|-
| +3.3 V || +3.15 V to +3.45 V || POWER2 / PowerPC / POWER3 CPU rails (on PSUs that supply it)
|-
| −12 V || −11.4 V to −12.6 V || RS-232 / legacy
|-
| −5 V || −4.75 V to −5.25 V || Legacy (omitted on some later PSUs)
|}

The exact per-machine PSU rating is in the corresponding IBM service guide. Documented values:

* '''7026-H70''' — 750 W PSU, FC 6290.<ref>https://www.amazon.com/IBM-6000-7026-H70-POWER-SUPPLY/dp/B000MRECHI</ref>
* '''7015 R10 / R20 / R21''' CPU drawer — 0.29 kVA typical, 200–240 V AC.
* '''7015 R24''' — 0.685 kVA typical, 200–240 V AC or −48 V DC.
* '''Per-machine watts for 7011, 7012, 7013, 7043''' — refer to SA38-0531 / SA38-0512.

== NVRAM / RTC Battery ==

The RS/6000 family uses '''Dallas Semiconductor TimeKeeper''' modules on the planar to hold real-time clock, system NVRAM and boot configuration. The internal lithium cell fails after 10–20 years, producing:

* Lost boot list (SMS boots from CD instead of disk after every power-cycle).
* Clock at epoch (1 Jan 1970 or similar).
* Lost machine serial number / model code (rare but possible if the part holds the IPL ROS / VPD).
* Solid LED panel halt at NVRAM tests (typically '''200''' / '''202''' / '''203''' on the LED panel — see [[IBM RS/6000 Troubleshooting Guide]]).

Common Dallas modules in the family include:

* '''DS1287 / DS1287A''' — 24-pin DIP, used on early MCA 7012 / 7013 planars (same family as PS/2 50/70/80).
* '''DS1385 / DS1387''' — DS1385 + integrated battery/crystal in an encapsulated module.
* '''DS1644''' — non-volatile TimeKeeping RAM.
* '''DS1742W''' — 32-pin nonvolatile timekeeping RAM, 5 V or 3 V variants.
* '''DS1746 / DS1746P''' — 128 KB × 8 NVSRAM + RTC, Y2K-compliant.

Replacement options:

# Direct replacement with a fresh-date Dallas/Maxim part (NOS or refurbished). DS12887+, DS1387 with cell replaced, DS1746P+.
# Modern drop-in board replacements such as the '''Glitch Works GW-1742-1''' (DS1742 substitute), '''GW-1387-1''' (DS1387 maintainable repair board) and '''Necroware nwX287''' (DS12887 replacement using a CR1225 + modern SRAM + RTC chip).<ref>https://www.tindie.com/products/glitchwrks/glitch-works-gw-1742-1-dallas-ds1742-replacement/</ref><ref>https://users.glitchwrks.com/~glitch/2017/07/27/ds1387-rebuild</ref>
# DIY: cut the Dallas plastic case open, find the internal cell, replace with an external CR2032 holder. Electrically valid but messy.

Replacement procedure:

# Power off; discharge PSU bulk capacitor.
# Identify the Dallas DIP on the planar — typically near the RTC crystal or near the boot ROM.
# Desolder with solder wick at no more than 350 °C. Limit each cycle to 5–7 seconds — RS/6000 planars are no more forgiving of repeated heating than PS/2 planars.
# Fit a socket (recommended) before fitting the replacement Dallas / Glitch Works / Necroware module.
# Power on; enter SMS (F1 or F4); re-enter boot list, IP / SLIP config, date/time.

After replacement, run '''SMS → Utilities → Update System Vital Product Data''' to write the machine serial back into NVRAM if the previous module had lost it.

== Capacitor Health ==

Through-hole tantalum capacitors and aluminium electrolytics on the planar, drive logic boards, GXT graphics cards and PSU all age. Full procedure: [[IBM RS/6000 Capacitor Replacement Guide]].

Specific known capacitor failure points:

* '''7012 / 7013 planar SMD aluminium electrolytics''' — same generation as PS/2 70/80 plague.
* '''7013 500-series PSU''' — will refuse to stay on if the cooling fan signal is lost. Aged secondaries cause fan stutter which causes PSU shutdown.<ref>https://www.ardent-tool.com/RS6000/docs/pdf/38053100.pdf</ref>
* '''POWER GXT graphics card decoupling''' — SMD tantalum on the GXT800P / GXT3000P boards can fail short and pull down the +5 V rail.

== Drive Maintenance ==

=== SCSI Spindle Stiction ===

Original IBM SCSI drives in long-stored RS/6000s are prone to spindle stiction. Symptoms: drive does not spin up; faint "thunk" on power-on but no rotation; SCSI BUS RESET timeouts.

Field fix (for one-time data recovery only):

* Power off.
* Pull the drive sled.
* Gently rotate the drive case 45–90° around its spindle axis to free the heads.
* Re-install. Power on.

Image the drive immediately to a modern SCSI-to-USB or SCSI2SD setup. The drive cannot be trusted to spin up reliably again.

=== SCSI Cable Replacement ===

The original IBM Centronics-50 / HD-50 SCSI cables in early RS/6000s develop intermittent contact in the IDC connectors. Replace with modern shielded cables (SCSI-3 cables are backward-compatible with SCSI-2 drives).

=== SCA-Tray Drives (7026 / 7044) ===

Hot-swap SCA-tray drives in the 7026 H-series and 7044-270 require the drive carrier to be fully inserted in the bay to register on the bus. Aged carrier latches can cause intermittent drive disappearance — clean the SCA connector with contact cleaner.

== Reference Diskette / Reference CD ==

Pre-CHRP RS/6000s (7011 / 7012 / 7013 / 7015) used per-machine '''Reference Diskettes''' for SETUP, similar in concept to the PS/2 line. CHRP RS/6000s (7025 / 7026 / 7043 / 7044) use the built-in '''SMS''' utility on Open Firmware — no Reference Diskette required.

The 7248 (PReP) uses a per-board firmware that boots to a text setup screen at POST.

== Cooling System ==

Restoration points:

* All RS/6000s with the original PSU fan are 30+ years old by now; the sleeve bearings are due for replacement. Listen for fan rattle or stutter on power-on.
* The 7013 500-series and 7015 rack systems require positive airflow to keep the MCM heatsink within thermal limits. A failed CPU fan on these can cause CPU overtemperature shutdown — visible in the LED panel as a thermal-class error.
* The 7044-270 PSU has redundant fans; one fan failure does not stop operation but is logged in the service processor diagnostic log.

== Connector Care ==

* '''Keyboard / mouse''' — RS/6000 desktops use either PS/2 Mini-DIN-6 ports (later submodels) or older AT-style 5-pin DIN (early submodels).
* '''Serial''' — DB-9 male on most submodels (RS-232C).
* '''Parallel''' — DB-25 female on submodels with parallel port.
* '''SCSI''' — Centronics-50 (early), HD-50 / HD-68 (later), SCA-2 80-pin (hot-swap).
* '''Ethernet''' — AUI on early submodels; 10Base-T / 100Base-TX RJ-45 on later submodels.
* '''Graphics''' — 13W3 connector (IBM GXT family; same as Sun) on most RS/6000 GXT cards; 15-pin DSUB on 7248 integrated graphics.

The '''13W3''' connector requires a 13W3-to-15-pin VGA adapter for use with modern monitors.

== Recommended Tools ==

* Philips #2 screwdriver and T15 Torx.
* Anti-static strap.
* Digital multimeter.
* IPA + foam swabs.
* Soldering iron with fine tip + solder wick.
* '''Hot-air rework station''' for SMD electrolytic removal on 7012 / 7013 planars.
* USB microscope for inspecting SMD cap leakage.
* SCSI2SD or BlueSCSI for replacement of original SCSI drives.
* 13W3-to-VGA adapter for monitor work.
* Spare Dallas DS12887+ or Glitch Works / Necroware NVRAM replacement.
* Per-machine IBM Service Guide PDF (SA38-0531, SA38-0512, etc.).

== Related Pages ==

* [[IBM RS/6000]]
* [[IBM RS/6000 Troubleshooting Guide]]
* [[IBM RS/6000 Capacitor Replacement Guide]]
* [[IBM RS/6000 Firmware Update Guide]]
* [[Recommended Tools]]

== References ==

* [https://www.ardent-tool.com/RS6000/docs/pdf/38053100.pdf IBM SA38-0531-00 — RS/6000 7013 500-series Installation and Service Guide]. Authoritative PSU + planar service.
* [https://sharktastica.co.uk/resources/docs/IBM_SA38-0512-03_RS6000_98_4.pdf IBM SA38-0512-03 — RS/6000 7043 / 7248 Service Guide]. 43P and Carolina service.
* [http://ps-2.kev009.com/rs6000/redbook-cd/sg245144.pdf IBM Redbook SG24-5144 — 43P Models 150 and 260 Handbook]. 7043 deep dive.
* [http://ps-2.kev009.com/rs6000/redbook-cd/sg245143.pdf IBM Redbook SG24-5143 — Models E30, F40, F50, H50 Handbook]. 7025 / 7026 deep dive.
* [http://www.ibmfiles.com/pages/rs6000type7044.htm IBM RS/6000 7044 family page, ibmfiles.com].
* [https://users.glitchwrks.com/~glitch/2017/07/27/ds1387-rebuild Glitch Works — DS1387 rebuild]. Reference for Dallas TimeKeeper failure mode and modern repair boards.
* [https://www.tindie.com/products/glitchwrks/glitch-works-gw-1742-1-dallas-ds1742-replacement/ Glitch Works GW-1742-1]. Drop-in DS1742 replacement.
* [https://www.minuszerodegrees.net/failure/failure.htm Commonly Failing Electronic Components, minuszerodegrees.net].

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IBM RS/6000 Maintenance Guide - Revision history

Josh: Deep technical RS/6000 page rewrite with verified sources, embedded images, full cap lists