Digital Equipment MicroVAX 3100 85 Guide

MicroVAX3100
Model85/95/96
TroubleshootingandDiagnostic
Information
Order Number: EK–A0719–TM. C01
DATE 1995
This manual describes the troubleshooting procedures and diagnostic
commands that you can use to solve basic problems with the
MicroVAX 3100 Model 85, Model 95, and Model 96 systems.
Revision Information: This manual supersedes
EK–A0719–TM. B01
Digital Equipment Corporation
Maynard, Massachusetts

DATE 1995
Digital Equipment Corporation makes no representations that the use of its products in the
manner described in this publication will not infringe on existing or future patent rights, nor do
the descriptions contained in this publication imply the granting of licenses to make, use, or sell
equipment or software in accordance with the description.
Possession, use, or copying of the software described in this publication is authorized only pursuant
to a valid written license from Digital or an authorized sublicensor.
FCC NOTICE: This equipment has been tested and found to comply with the limits for a Class
A digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide
reasonable protection against harmful interference when the equipment is operated in a commercial
environment. This equipment generates, uses, and can radiate radio frequency energy and, if not
installed and used in accordance with the instruction manual, may cause harmful interference to
radio communications.
Any changes or modifications made to this equipment may void the user’s authority to operate this
equipment.
Operation of this equipment in a residential area may cause interference in which case the user
at his own expense will be required to take whatever measures may be required to correct the
interference.
© Digital Equipment Corporation 1994. All Rights Reserved.
The postpaid Reader’s Comments form at the end of this document requests your critical evaluation
to assist in preparing future documentation.
The following are trademarks of Digital Equipment Corporation: Digital, MicroVAX, OpenVMS, RX,
ThinWire, VAX, VAX DOCUMENT, and the DIGITAL logo.
All other trademarks and registered trademarks are the property of their respective holders.
S2811
This document was prepared using VAX DOCUMENT Version 2.1.

Contents
Preface ................................................ v
1 Troubleshooting and Diagnosing Problems
1.1 Troubleshooting . . ............................... 1–1
1.2 Using the Troubleshooting Table .................... 1–2
1.3 Diagnostic Tests and Commands .................... 1–9
1.3.1 Power-Up Tests .............................. 1–10
1.3.2 Diagnostic Tests and Utilities ................... 1–13
1.3.3 Power-Up Error Messages ...................... 1–18
1.3.4 Configuration Display . . ....................... 1–22
1.3.5 Error Display . ............................... 1–24
1.4 Contacting Digital Services . ....................... 1–25
Index
Examples
1–1 SYNC Test Failure ............................ 1–18
1–2 Memory_Setup_CSRs Test Failure . ............... 1–19
1–3 Memory_Count_Pages Test Failure ............... 1–20
1–4 No_Memory_Present Test Failure . ............... 1–21
iii

Figures
1–1 Diagnostic Tests .............................. 1–13
1–2 Status LED Display ........................... 1–26
Tables
1–1 Basic Troubleshooting . . ....................... 1–3
1–2 Option Card Tests ............................ 1–15
1–3 MicroVAX 4000-100A/105A Tests . . ............... 1–16
iv

Preface
This manual describes the troubleshooting procedures and diagnostic commands
that you can use to solve basic problems with the MicroVAX™ 3100 Model 85,
Model 95, and Model 96 systems.
Audience
This manual is intended for people who have some experience with computers.
Structure of This Manual
This manual presents the information you need for solving basic problems with
the MicroVAX 3100 Model 85/95/96 system in one chapter. Use the sections in
the order presented, starting with Section 1.1, Troubleshooting, when solving
a problem with your system. You can follow up with diagnostic testing or by
contacting Digital services for support as described in Section 1.3 and Section 1.4.
Additional Information
See the MicroVAX 3100 Model 85/95/96 Operator Information manual for the
list of related documents.
v

Conventions
The following conventions are used in this manual:
Convention Description
MONOSPACE type Text displayed on the screen is shown in monospace type.
italic type Italic type emphasizes important information and indicates the
complete titles of manuals.
Note A note contains information that is of special importance to the
user.
Warning A warning contains information to prevent personal injury.
vi

1
Troubleshooting and Diagnosing
Problems
This chapter describes the troubleshooting procedures and diagnostic commands
that you can use to solve basic problems with the MicroVAX 3100 Model 85,
Model 95, and Model 96 systems. It contains information on the following:
• Troubleshooting
• Diagnostic tests and commands
• Contacting Digital™ services
It also lists the information that you must give to your Digital services
representative and where to find this information.
1.1 Troubleshooting
If a problem occurs, you must first make sure that all the cables, loopback
connectors, and terminators are correctly connected and that the connectors are
not damaged, for example, the pins may be broken or short-circuited.
Follow these steps:
1. Shut down the operating system by following the procedures described in the
operating system documentation.
2. Turn off the console terminal and all the peripheral devices, such as printers
and modems.
3. Turn off all the expansion boxes.
4. Turn off the system unit.
5. Check that the following cables, if installed, are correctly connected at both
ends and that the connectors are not damaged:
• Console terminal cable (linking the console terminal to the system unit)
• Console terminal power cord
Troubleshooting and Diagnosing Problems 1–1

• System unit power cord
• Expansion box SCSI cables
• Expansion box power cords
• ThinWire™ Ethernet cable or standard Ethernet cable
6. Check that the following terminators, if installed, are correctly connected and
are not damaged:
• SCSI terminators
• ThinWire Ethernet terminator (T-connector and two terminators)
• Standard Ethernet loopback connector
If you have correctly followed steps 1 to 5, the on/off switches on all the
components are set to the off (O) position, and you have solved any problems
caused by incorrectly connected cables or terminators.
7. Set the on/off switches on the following equipment to the on (|) position in
the following order:
a. Expansion boxes
b. Peripherals
c. Console terminal
d. System unit
The system responds with the power-up test display. If it does not, see
Section 1.2.
1.2 Using the Troubleshooting Table
Table 1–1 suggests the corrective actions for certain system problems. If you have
a problem with the system, follow these steps:
1. Write down the symptoms of the problem.
2. Check the Symptom column in Table 1–1 for a match.
3. Check the causes of the symptom in the Possible Cause column. If the
column lists more than one possible cause, check the possible causes and
their suggested solutions in the order listed.
4. Follow the advice in the Suggested Solution column.
5. See Section 1.4 if the problem persists.
1–2 Troubleshooting and Diagnosing Problems

Table 1–1 Basic Troubleshooting
Symptom Possible Cause Suggested Solution
System Problems
The system unit fan is
off or the power light is
off.
The power cord is not
connected. The power
cord may be faulty. The
power socket may not
be working. The system
breaker or wall outlet
may have blown.
Make sure that all the power cords
are connected correctly at both
ends. Try a known good power cord
or test the power socket with an
appliance that works.
The overload protection
circuitry of the power
supply may have shut
down because of an
abnormal condition on
the power line.
Turn the system off and then turn
it back on.
The power supply unit
(PSU) is faulty. Contact your Digital services representative.
The power-up display
does not show after 20
seconds.
The terminal cable is
not correctly connected. Make sure that all the cables are connected at both ends.
The terminal cable is
not connected to the
correct MMJ port.
Check the MMJ port to which the
terminal cable is connected. If this
port is not MMJ port 3, remove the
terminal cable and connect it to
MMJ port 3.
The power cord is not
connected. The power
cord may be faulty. The
wall outlet may not be
working.
Make sure that all the power cords
are connected correctly at both
ends. Try a known good power cord
or test the power socket with an
appliance that works.
The terminal fuse may
have blown. Replace the blown terminal fuse. See the terminal documentation.
The terminal settings
may be incorrect. See the MicroVAX 3100 Model 85/95/96 Operator Information
manual for the list of correct
terminal settings. See the terminal
documentation for information on
how to set up the terminal.
(continued on next page)
Troubleshooting and Diagnosing Problems 1–3

Table 1–1 (Cont.) Basic Troubleshooting
Symptom Possible Cause Suggested Solution
System Problems
The port to which the
terminal connects may
be faulty.
Try connecting the terminal to
another system. If this solution
works, the port to which the
terminal was connected is faulty.
If the terminal still does not
operate, it is faulty. In either
case, contact your Digital services
representative.
The terminal cable may
be faulty. Connect the terminal cable and the terminal to another system.
If the connected terminal works,
the DZ circuitry or MMJ connector
is faulty. Otherwise, the cable
is faulty. Contact your Digital
services representative.
The power-up display
contains question marks. A diagnostic error has occurred. See Section 1.4.
The power-up test
display contains
unexpected characters.
The terminal settings
are incorrect or the DZ
circuitry is faulty.
Make sure the terminal settings
are correct, then run the power-
up test again. If the terminal is
set correctly, contact your Digital
services representative.
The system fails to boot
the operating system. The system defaults are incorrectly set. Set the system defaults as described in the OpenVMS
Factory Installed Software User
Information document, then try
to boot the system again. If
the system still fails to boot,
contact your Digital services
representative.
(continued on next page)
1–4 Troubleshooting and Diagnosing Problems

Table 1–1 (Cont.) Basic Troubleshooting
Symptom Possible Cause Suggested Solution
RRD43 Compact Disc Drive Problems
The drive does not
accept the disc. The disc is upside-down in the tray or it is not
placed correctly in the
tray.
Remove the disc from the tray and
reinsert it properly.
A disc is already
present. Remove the disc and replace it with a new one.
The eject button fails to
release the disc tray. The eject button is disabled by software. Reenable the eject button or manually release the disc tray.
The system does not
have power. Set the system unit on/off switch to the on (|) position and press the
eject button again.
The RRD43 compact disc
drive is faulty. If you want to release the disc tray manually, see MicroVAX
3100 Model 85/95/96 Operator
Information for instructions. If
the problem persists, contact your
Digital services representative.
(continued on next page)
Troubleshooting and Diagnosing Problems 1–5

Table 1–1 (Cont.) Basic Troubleshooting
Symptom Possible Cause Suggested Solution
TZ30 Tape Drive Problems
The TZ30 green LED
flashes rapidly. The drive mechanism is faulty or the tape
cartridge is damaged.
Press and release the unload
button to clear the fault. If the
LED continues to flash, do not try
to remove the tape cartridge or
use the tape drive. Contact your
Digital services representative.
The TZ30 does not
operate. The drive does not contain a tape cartridge. Insert the tape cartridge and slide the lever from the UNLOCK to the
LOCK position.
The operate lever does
not slide. The tape cartridge is in use. Wait for the green LED to turn on and try again. If the problem
persists, do not use the drive.
Contact your Digital services
representative.
The operate lever does
not lock. The tape cartridge is not inserted correctly. Reinsert the tape cartridge. If the problem persists, contact your
Digital services representative.
The tape does not load. Press and release the unload
button. Wait for the green LED
to turn on before sliding the lever
and removing the tape. If the
LED flashes, contact your Digital
services representative.
The system cannot write
to the tape. The write-protect switch is in the write-protect
position.
If the write-protect LED is on,
remove the tape, reset the switch
and try writing to the tape
again. If the problem persists,
contact your Digital services
representative.
The data read from
the tape cartridge is
corrupted.
The tape drive head may
be dirty. See the MicroVAX 3100 Model 85/95/96 Operator Information
manual for information on how to
clean the drive head.
The tape does not eject. The tape is not rewound.
The operate lever is in
the lock position.
Follow the procedure for removing
a tape from the TZ30 described in
the MicroVAX 3100 Model 85/95
/96 Operator Information manual.
(continued on next page)
1–6 Troubleshooting and Diagnosing Problems

Table 1–1 (Cont.) Basic Troubleshooting
Symptom Possible Cause Suggested Solution
TLZ06 and TLZ07 Cassette Tape Drive Problems
The system cannot write
to the cassette tape. The write-protect switch is in the write-protect
position.
If the write-protect LED is on,
remove the tape, reset the switch
and try writing to the tape
again. If the problem persists,
contact your Digital services
representative.
The cassette tape is not
loaded. Load the cassette tape.
The write-protect LED
flashes. The tape drive heads are dirty or the tape is
worn.
Clean the drive heads (see the
MicroVAX 3100 Model 85/95/96
Operator Information manual). If
the problem persists, use a new
tape.
The data read from
the cassette tape is
corrupted.
The tape drive heads
may be dirty. See the MicroVAX 3100 Model 85/95/96 Operator Information
manual for information on how to
clean the drive heads.
TZK10/TZK11 Quarter Inch Cartridge (QIC) Tape Drive Problems
The data read from the
QIC tape is corrupted. The drive head is dirty. Clean the drive head. See the MicroVAX 3100 Model 85/95/96
Operator Information manual.
The system cannot write
to the QIC tape. The write-protect switch is in the write-protect
position.
Remove the QIC tape, reset the
switch and try to write to the
QIC tape again. If the problem
persists, contact your Digital
services representative.
The system cannot read
from or write to the QIC
tape.
The QIC tape may be
faulty. Remove the QIC tape. If the amber LED turns off when you remove
the QIC tape, the tape is probably
faulty. Try a different QIC tape.
If the amber LED stays on or if
the problem persists, contact your
Digital services representative.
(continued on next page)
Troubleshooting and Diagnosing Problems 1–7

Table 1–1 (Cont.) Basic Troubleshooting
Symptom Possible Cause Suggested Solution
RX™26 Diskette Drive Problems
The system cannot read
from or write to the
diskette.
The diskette is not
formatted. Format the diskette.
The diskette is not
correctly inserted. Eject the diskette. Try to insert the diskette again.
The diskette is faulty. Try a different diskette.
The diskette drive is
faulty. Contact your Digital services representative.
The diskette density is
incorrect. The RX26 accepts only high- density (HD) or extra-density
(ED) diskettes.
The diskette drive head
may be dirty. See the MicroVAX 3100 Model 85/95/96 Operator Information
manual for information on how to
clean the diskette drive head.
The system can read
from but cannot write to
a diskette.
The write-protect switch
is in the write-protect
position.
Eject the diskette and reset the
switch. Try writing to the diskette
again.
The diskette does not
eject. The diskette is incorrectly positioned
in the drive.
Gently press the diskette with your
finger and reposition it. Press the
eject button again.
RZ-Series SCSI Disk Drive Problems
An installed drive does
not work. Two SCSI identifiers are set to the same number. Reset each SCSI ID to a unique number.
Drive cables are not
properly connected. Check the cable connections.
The Configuration
display does not show a
SCSI device.
SCSI device is not
properly terminated. Check for a SCSI 50-pin terminator.
Two SCSI identifiers are
set to the same number. Reset each SCSI ID to a unique number.
1–8 Troubleshooting and Diagnosing Problems

1.3 Diagnostic Tests and Commands
There are a number of diagnostic tests and commands that can help you to isolate
a problem with the system unit. These tests and commands are as follows:
• Power-up tests
• Diagnostic tests and utilities1
• Configuration display1
• Error display1
The following sections describe these tests and commands.
1You can use these tests and commands in privileged console mode only if the
console security feature is enabled and the password is set. See the MicroVAX 3100
Model 85/95/96 Customer Technical Information manual for information on the console
security feature.
Troubleshooting and Diagnosing Problems 1–9

1.3.1 Power-Up Tests
The system runs the power-up tests each time you turn on the system. After
successful completion of tests, the system will either enter console mode or
proceed to automatic bootstrap, depending on the HALT action selected by the
user. If HALT action is Default, Halt, or Restart, then the system enters console
mode. If HALT action is Reboot or Restart_reboot, then the system proceeds to
boot. The following example shows a typical display for a system that passes all
tests and then enters console mode.
KA55-A or KA51-A or KA56-A V2.6, VMB 2.15 !
Performing normal system tests.
74..73..72..71..70..69..68..67..66..65..64..63..62..61..60..59..
58..57..56..55..54..53..52..51..50..49..48..47..46..45..44..43.. "
42..41..40..39..38..37..36..35..34..33..32..31..30..29..28..27..
26..25..24..23..22..21..20..19..18..17..16..15..14..13..12..11..
10..09..08..07..06..05..04..03..
Tests completed. #
>>> $
!
Central Processing Unit (CPU) Name, Firmware Version Number, and Virtual
Memory Boot (VMB) Version Number
" Read-Only Memory (ROM) Based Diagnostics Countdown
# Status Message
$ Console Prompt
1–10 Troubleshooting and Diagnosing Problems

The following example shows a typical display for a system that passes all tests
and then enters automatic bootstrap.
KA55-A or KA51-A or KA56-A V2.6, VMB 2.15
Performing normal system tests.
74..73..72..71..70..69..68..67..66..65..64..63..62..61..60..59..
58..57..56..55..54..53..52..51..50..49..48..47..46..45..44..43..
42..41..40..39..38..37..36..35..34..33..32..31..30..29..28..27..
26..25..24..23..22..21..20..19..18..17..16..15..14..13..12..11..
10..09..08..07..06..05..04..03..
Tests completed.
Loading system software.
(BOOT/R5:0 EZA0)
2..
-EZA0
1..0..
Note
The operating system messages start here, that is VMS . . .
If the power-up tests encounter an error, one of the following actions occurs:
For minor errors:
• If HALT action is set to a boot condition (that is reboot or restart_reboot),
and if a minor error occurs, the system displays an abbreviated error
message and continues to boot as normal.
• If HALT action is set to Default, Halt or Restart, then the system enters
console mode.
• The only errors defined as minor are errors in memory that cause pages
to be marked bad in the memory bitmap. There must be enough good
memory left to allow an attempt to bootstrap.
For severe errors:
• The system always enters console mode regardless of HALT action after it
attempts to complete all tests possible.
Troubleshooting and Diagnosing Problems 1–11

The following example shows a system with a memory error that only affected one
set of memory out of two sets. Because some memory is still usable, the system
proceeds to automatic bootstrap if the HALT action is set to a boot condition.
KA55-A or KA51-A or KA56-A V2.6, VMB 2.15
Performing normal system tests.
74..73..72..71..70..69..68..67..66..65..64..63..62..61..60..59..
58..57..56..55..54..53..52..51..50..49..48..47..46..45..44..43..
42..41..40..39..38..37..36..35..34..33..32..
? Test_Subtest_40_06 Loop_Subtest=00 Err_Type=FF DE_Memory_count_pages.lis
31..30..29..28..27..26..25..24..23..22..21..20..19..18..17..16..
15..14..13..12..11..10..09..08..07..06..05..04..03..
16 MB RAM, SIMM Set (0A,0B,0C,0D) present
Memory Set 0: 04000000 to 04FFFFFF, 16MB, 0 good pages, 32768 bad pages
64 MB RAM, SIMM Set (1E,1F,1G,1H) present
Memory Set 1: 00000000 to 03FFFFFF, 64MB, 131072 good pages, 0 bad pages
Total of 80MB, 131072 good pages, 32768 bad pages, 136 reserved pages
Tests completed.
Loading system software.
(BOOT/R5:0 EZA0)
2..
-EZA0
1..0..
!
? Test_Subtest_40_06 Loop_Subtest=00 Err_Type=FF DE_Memory_count_pages.lis "
16 MB RAM, SIMM Set (0A,0B,0C,0D) present
Memory Set 0: 04000000 to 04FFFFFF, 16MB, 0 good pages, 32768 bad pages
64 MB RAM, SIMM Set (1E,1F,1G,1H) present
Memory Set 1: 00000000 to 03FFFFFF, 64MB, 131072 good pages, 0 bad pages
Total of 80MB, 131072 good pages, 32768 bad pages, 136 reserved pages
! Operating system messages start here; that is VMS . . .
" Abbreviated error message for memory error
Memory errors normally cause the results of a SHOW MEMORY display to occur
after the tests are completed and before continuing. SHOW MEMORY is the
most useful command to determine which memory SIMMs are bad when memory
errors occur.
1–12 Troubleshooting and Diagnosing Problems

1.3.2 Diagnostic Tests and Utilities
The diagnostic tests and utilities are similar to the power-up tests except that
the power-up tests enable you to test all the devices in the system, whereas the
diagnostic tests and utilities enable you to test single devices and the functions of
single devices.
Figure 1–1 shows a list of diagnostic tests obtained by entering the following
command:
>>> T9E
Figure 1–1 Diagnostic Tests
Test
# Address Name Parameters
___________________________________________________________________________
20052200 SCB
20055850 De_executive
30 2006A53C Memory_Init_Bitmap *** mark_Hard_SBEs ******
31 2006AB34 Memory_Setup_CSRs *********
32 2005D148 NMC_registers **********
33 2005D324 NMC_powerup **
34 2005E6D8 SSC_ROM ***
35 2005FB90 B_Cache_diag_mode bypass_test_mask *********
37 20061590 Cache_w_Memory bypass_test_mask *********
40 2006B5E0 Memory_count_pages SIMM_set0 SIMM_set1 Soft_errs_allowed *****
41 20068CEC Board_Reset *
42 20061880 Chk_for_Interrupts **********
46 200610C4 P_Cache_diag_mode bypass_test_mask *********
47 2006AD04 Memory_Refresh start_a end incr cont_on_err time_seconds *****
48 2006B028 Memory_Addr_shorts start_add end_add * cont_on_err pat2 pat3 ****
4A 2006A23C Memory_ECC_SBEs start_add end_add add_incr cont_on_err ******
4B 2006940C Memory_Byte_Errors start_add end_add add_incr cont_on_err ******
4C 20069BA0 Memory_ECC_Logic start_add end_add add_incr cont_on_err ******
4D 20068FE8 Memory_Address start_add end_add add_incr cont_on_err ******
4E 20069188 Memory_Byte start_add end_add add_incr cont_on_err ******
4F 2006B7F4 Memory_Data start_add end_add add_incr cont_on_err ******
51 2005803C FPA **********
52 20058530 SSC_Prog_timers which_timer wait_time_us ***
53 20058818 SSC_TOY_Clock repeat_test_250ms_ea Tolerance ***
54 20057C18 Virtual_Mode ********
55 20058E6C Interval_Timer *****
56 2006507C SHAC_LPBCK From_bus To_bus passes *******
58 20065D24 SHAC_RESET dssi_bus port_number time_secs not_pres *
59 20062778 SGEC_LPBCK_ASSIST time_secs **
(continued on next page)
Troubleshooting and Diagnosing Problems 1–13

Figure 1–1 (Cont.) Diagnostic Tests
5C 20062D10 SHAC SHAC_number *********
5F 200619B8 SGEC loopback_type no_ram_tests ******
62 20058B1C console_QDSS mark_not_present selftest_r0 selftest_r1 *****
63 20058CA4 QDSS_any input_csr selftest_r0 selftest_r1 ******
80 2005D3C0 CQBIC_memory bypass_test_mask *********
81 200596CC Qbus_MSCP IP_csr ******
82 200598AC Qbus_DELQA device_num_addr ****
83 2005A85C QZA_Intlpbck1 controller_number ********
84 2005BF1C QZA_Intlpbck2 controller_number *********
85 20059A9C QZA_memory incr test_pattern controller_number *******
86 20059F44 QZA_DMA Controller_number main_mem_buf ********
90 20058494 CQBIC_registers *
91 20058410 CQBIC_powerup **
99 2005DC4C Flush_Ena_Caches dis_flush_VIC dis_flush_BC dis_flush_PC
9A 20063FB0 INTERACTION pass_count disable_device *******
9B 20068E48 Init_memory **
9C 2006631C List_CPU_registers *
9D 2006C250 Utility Flags *********
9E 2005903C List_diagnostics script_number *
9F 200681CC Create_A0_Script **********
C1 20057888 SSC_RAM_Data *
C2 20057A78 SSC_RAM_Data_Addr *
C5 200589E8 SSC_registers *
D0 20060C70 V_Cache_diag_mode bypass_test_mask *********
D2 2005DE90 O_Bit_diag_mode bypass_test_mask *********
DA 2006139C PB_Flush_Cache **********
DB 2005E850 Speed print_speed *********
DC 2006C060 NO_Memory_present *
DD 2005F0DC B_Cache_Data_debug start_add end_add add_incr *******
DE 2005EC64 B_Cache_Tag_Debug start_add end_add add_incr *******
DF 2005E2A8 O_BIT_DEBUG start_add end_add add_incr seg_incr ******
E0 2006D4D4 SCSI environment reset_bus time_s *******
E1 2006D7CC SCSI_Utility environment util_nbr target_ID lun ******
E2 2006DA2C SCSI_MAP bypass_test addr_incr_data_tst ********
E4 2006DFC8 DZ environment *********
E8 2006E1DC SYNC environment *********
E9 2006E2B4 SYNC_Utility environment *********
EC 2006E398 ASYNC environment *********
F0 2006D638 SCSI_option environment reset_bus time_s *******
F1 2006D900 SCSI_Opt_Utility environment util_nbr target_ID lun ******
F2 2006DA40 SCSI_MAP_Option bypass_test addr_incr_data_tst ********
Scripts
# Description
(continued on next page)
1–14 Troubleshooting and Diagnosing Problems