Editing DECpc 433 Troubleshooting Guide

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[[File:DECpc 433 Workstation rear panel (bitsavers).jpg|thumb|right|340px|Rear of a DECpc 433 Workstation (model PCW10-A2). The rotary video select switch beside the video connector is the first thing DEC checks when there is no picture (bitsavers.org)]]
Fault-finding on the '''[[DECpc 433]]''' Workstation from chapter 2 of DEC's ''DECpc 433 Workstation Service Guide'' (ER-PCW10-SV-001) and the ''Technical Reference Manual'' (ER-PCW1A-TR).<ref name="sg" /><ref name="trm" /> The BIOS is Phoenix's 80486 ROM BIOS PLUS.<ref name="sg5" />

== DEC's first steps ==
# Check the power indicators on the system box, the SCSI expansion box, the monitor and any peripherals.
# Check for loose cables and connections.
# Switch on. If the machine does not boot, switch off, wait 20 seconds and switch on again.
# Note any POST message or beep code and act on it using the tables below.
<ref name="sg15" />

== Power-on self-test ==
POST tests the system board first: interrupt controller, 82340 chip set, CPU, keyboard controller, CMOS RAM, ROM checksum, timer, DMA, the first 64 KB of RAM and the cache controller. A failure there is fatal and is reported by beeps, an on-screen message, or fault LEDs on the system board and graphics controller. POST then checks the configuration in CMOS against the hardware, the rest of the memory, keyboard, serial and parallel ports, floppy and hard disk controllers and the graphics controller.<ref name="sg3" /> While it runs, the screen counts down from 240 to 000; the memory count can take up to 60 seconds. A clean run gives one beep; an error gives two beeps and a message.<ref name="sg5" />

{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+ '''POST error messages (DEC Table 2-2)'''
! Count !! Code !! Message !! DEC's action
|-
| 240 || 0007 || No timer tick || Replace the system board
|-
| 200 || 0001 || Gate A20 failure || Replace the system board
|-
| 190 || 0009 || Timer 2 failure || Replace the system board
|-
| 180 || 0010 || Keyboard stuck key, keyboard controller, clock line, data line or keyboard failure || Check the keyboard connection and for a stuck key; replace the keyboard
|-
| 170 || 0041 || Pointing device failure || Check the mouse connection; replace the mouse
|-
| 160 || – || 640 KB base memory, 0 KB extended memory || Replace the system board
|-
| 150 || 0017 || Time-of-day clock stopped || Replace the system board
|-
| 100 || 0018 || Invalid configuration information || Run Setup
|-
| 090 || 0011 || Floppy disk drive failure || Check connections; replace the drive
|-
| 080 || 0015, 0016 || Hard disk controller failure; hard disk 0 failure || Check connections; replace the hard disk
|-
| 070 || 43 || No SCSI BIOS found || Check SCSI connections; replace the system board
|-
| 070 || 210–215 || SCSI target 0 not connected, faulty, not a disk, not ready, capacity read failed, or not 512-byte blocks || Check the expansion box connection and SCSI IDs, run Setup, or replace the drive
|-
| 070 || 200 || Host adapter diagnostic failure || SCSI hardware failure
|-
| 060 || 0021 || Optional ROM bad checksum || Correct the address conflict or replace the ROM
|-
| 060 || 71–8C || LAN memory, hardware, I/O, interrupt or mouse-interrupt failure || Replace the system board
|-
| 050 || 0019 || Time-of-day not set || Run Setup and set the time and date
|-
| 040 || 0020 || Keyboard is locked || Unlock the keyboard
|}
<ref name="sg7" />

Messages 0017, 0018 and 0019 all involve the battery-backed clock and CMOS RAM. Before replacing a system board for them, check the clock battery on header J8: DEC's parts list gives it as a 4.5 V pack, and on the machine photographed for bitsavers it is a non-rechargeable alkaline Duracell pack, now decades old. DEC's battery procedure ends with re-entering the configuration in Setup.<ref name="sg23" /><ref name="sg3p" /><ref name="photo" />

== Beep codes ==
When POST cannot show a message it sounds a beep code and writes a value to I/O port 80h, which a POST card can read. A code such as 2-1-4 is a burst of two beeps, one beep, then four.<ref name="sg11" />

{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+ '''Fatal and non-fatal beep codes (DEC Tables 2-3 and 2-4)'''
! Beeps !! Port 80h !! Error
|-
| 1-1-3 || 02h || RTC write/read failure
|-
| 1-1-4 || 03h || ROM BIOS checksum failure
|-
| 1-2-1 || 04h || Programmable interval timer failure
|-
| 1-2-2 || 05h || DMA initialisation failure
|-
| 1-2-3 || 06h || DMA page register write/read failure
|-
| 1-3-1 || 08h || DRAM refresh verification failure
|-
| 1-3-3 || 0Ah || First 64 KB DRAM chip or data line failure
|-
| 1-3-4 || 0Bh || First 64 KB DRAM odd/even logic failure
|-
| 1-4-1 || 0Ch || First 64 KB DRAM address line failure
|-
| 1-4-2 || 0Dh || First 64 KB DRAM parity test in progress or failure
|-
| 2-1-1 to 2-4-4 || 10h to 1Fh || Bits 0 to F of the first 64 KB of DRAM, in order (2-1-1 is bit 0, 2-1-4 bit 3, 2-4-4 bit F)
|-
| 3-1-1 || 20h || Slave DMA register failure
|-
| 3-1-2 || 21h || Master DMA register failure
|-
| 3-1-3 || 22h || Master interrupt mask register failure
|-
| 3-1-4 || 23h || Slave interrupt mask register failure
|-
| 3-2-4 || 27h || Keyboard and mouse controller test failure
|-
| 3-3-4 || 2Bh || Screen memory test failure (non-fatal)
|-
| 3-4-1 || 2Ch || Screen initialisation failure (non-fatal)
|-
| 3-4-2 || 2Dh || Screen retrace test failure (non-fatal)
|}
<ref name="sg12" />

The intelligent graphics controller has its own codes of long and short beeps and writes nothing to port 80h:<ref name="sg11" /><ref name="sg14" />
{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+ '''Intelligent graphics controller beep codes (DEC Table 2-5)'''
! Long !! Short !! Failed test
|-
| 1 || 1 || VGA RAMDAC
|-
| 1 || 2 || Monitor detection (RGB line loading or BT459 test circuit)
|-
| 1 || 3 || VGA display memory
|-
| 1 || 4 || VGA retrace (no vertical retrace)
|-
| 1 || 5 || Other adapter (a CGA or MDA card fitted and failing)
|-
| 1 || 6 || Xilinx programming
|-
| 2 || 1 || Frequency synthesiser (SC22318) programming
|-
| 2 || 2 || BT459 RAMDAC register test
|-
| 2 || 3 || GSP POST time-out
|-
| 2 || 4 || Register read/write to the i486 registers and GSP configuration register
|-
| 2 || 5 || Frame-grab hardware
|-
| 2 || 6 || GSP memory (VRAM and DRAM)
|-
| 3 || 1 || Controller disabled by a reserved video switch setting
|}
<ref name="sg14" />

== System box faults ==
{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+ '''System box, disk and monitor faults (from DEC Tables 2-6 to 2-8)'''
! Problem !! Possible cause !! Action
|-
| No response at switch-on || Not plugged in, or no power at the outlet || Plug in; try another outlet
|-
| Power on, no picture || Video select switch in the wrong position; monitor off; monitor cable wrong || Check the switch position; switch the monitor on; check the cable
|-
| Partly highlighted characters, rolling or flickering picture, wrong colours || Video select switch wrong; monitor adjustment; bent pins in the monitor cable || Check the switch; adjust; straighten pins and reseat
|-
| Colour monitor shows monochrome || System box switched on before the monitor || Switch the system box off, the monitor on, then the system box on
|-
| Hangs at start-up although its Ethernet address is set up on the server || Software not installed on the server, network failure, or network select switch in the wrong position || Check with the network administrator; set the network select switch correctly
|-
| Will not boot from the IDE disk || No operating system, unformatted or unpartitioned disk, wrong jumpers or drive type, loose cable || Install, format or partition; check jumpers; run Setup
|-
| Will not boot from the diskette || Drive ID not set to 1, no system files, worn diskette, loose cable || Set the drive ID to 1; use a bootable diskette
|-
| No response to the keyboard || Keyboard password set; keyboard unplugged or in the mouse port || Enter the password; plug into the keyboard port
|}
<ref name="sg16" />

== SCSI expansion box ==
The expansion box takes its mains from the system box. If its power light is out, check that its cord is plugged into the system box and that the system box is plugged in; otherwise its 63 W supply has failed.<ref name="sg20" /> If the machine will not boot from a SCSI disk, DEC's list is: no operating system, partition missing, drive jumpers, SCSI ID conflicts, terminating resistors left on the drive, the external terminator missing, or Setup not configured for SCSI.<ref name="sg20" />

== Power supply ==
DEC treats the 105 W supply as a replaceable unit and publishes no component data for it. Its outputs should be +5 V ±5% (up to 18 A), +12 V ±5% (1 A, 2 A peak), −12 V ±10% and −5 V ±10% (0.2 A each).<ref name="trm11" /> Warning: the supply is mains powered; unplug the system box before removing it.<ref name="sg3c" />

== Clearing passwords and CMOS ==
Jumpers on the system board clear a forgotten password or the CMOS RAM:<ref name="trm4" />
{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+ '''System board jumpers (DEC Table 4-13)'''
! Feature !! Normal (default) !! Clear
|-
| Password || E1-1 and E1-2 || E1-2 and E1-3
|-
| CMOS RAM || E1-4 and E1-5 || E1-5 and E1-6
|}
<ref name="trm4" />

== Related pages ==
* [[DECpc 433]]
* [[DECpc 433 General Maintenance]]
* [[DECpc 433 Documentation]]
* [[Battery Explosion, Capacitor or Corrosion Damage]]
* [[Hard Drive Maintenance and Repair]]

== References ==
<references>
<ref name="sg">Digital Equipment Corporation, ''DECpc 433 Workstation Service Guide'', ER-PCW10-SV-001, June 1991 ([[:File:DECpc 433 Workstation Service Guide (ER-PCW10-SV-001).pdf]]).</ref>
<ref name="sg3">DEC, ER-PCW10-SV-001, pp. 2-3 to 2-4. POST system board and peripheral tests.</ref>
<ref name="sg5">DEC, ER-PCW10-SV-001, pp. 2-5 to 2-6. POST sequence, countdown, Phoenix BIOS banner.</ref>
<ref name="sg7">DEC, ER-PCW10-SV-001, pp. 2-7 to 2-10, Table 2-2, "POST Error Messages".</ref>
<ref name="sg11">DEC, ER-PCW10-SV-001, p. 2-11. Beep codes and port 80h.</ref>
<ref name="sg12">DEC, ER-PCW10-SV-001, pp. 2-12 to 2-13, Tables 2-3 and 2-4.</ref>
<ref name="sg14">DEC, ER-PCW10-SV-001, p. 2-14, Table 2-5.</ref>
<ref name="sg15">DEC, ER-PCW10-SV-001, p. 2-15. Initial troubleshooting.</ref>
<ref name="sg16">DEC, ER-PCW10-SV-001, pp. 2-16 to 2-19, Tables 2-6, 2-7 and 2-8.</ref>
<ref name="sg20">DEC, ER-PCW10-SV-001, pp. 2-20 to 2-21, Table 2-9.</ref>
<ref name="sg23">DEC, ER-PCW10-SV-001, pp. 3-23 to 3-24. System battery on header J8.</ref>
<ref name="sg3p">DEC, ER-PCW10-SV-001, p. 3-2, Table 3-1. Battery, 4.5 V dc, 29-28951-01.</ref>
<ref name="sg3c">DEC, ER-PCW10-SV-001, p. 3-3. Warning on disconnecting power before opening the covers.</ref>
<ref name="trm">Digital Equipment Corporation, ''DECpc 433 Workstation Technical Reference Manual'', ER-PCW1A-TR, December 1991 ([[:File:DECpc 433 Workstation Technical Reference Manual (ER-PCW1A-TR).pdf]]).</ref>
<ref name="trm4">DEC, ER-PCW1A-TR, p. 4-19, Table 4-13. System board jumper settings.</ref>
<ref name="trm11">DEC, ER-PCW1A-TR, p. 11-1, Table 11-1. 105 W power supply.</ref>
<ref name="photo">Photograph of the clock battery in DECpc 433 serial number 2B21100274, [http://bitsavers.org/pdf/dec/decpc/DECpc_433/sn_2B21100274/ bitsavers.org] ([[:File:DECpc 433 alkaline clock battery and corrosion (bitsavers).jpg]]). Duracell MN1500CCB alkaline 4.5 V pack.</ref>
</references>

[[Category:Digital Equipment Corporation]]
[[Category:Troubleshooting Guides]]