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Some history of IBM 5150/5155/5160/5170 Motherboard Failure
at the Vintage Computer Federation Forums


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Date Thread#Post Member Motherboard Cause   Comment
OCT06 4573 the xt guy 5150 RAM  
NOV06 5414 mR_Slug 5160 Tantalum cap  C56 (sits on +12V line).
JAN08 9622 dkedrowitsch 5170 BIOS ROM  Offline, determined that his 61X9265 EPROM had corrupted contents.
MAR08 10586 crazypigeon 5150 Tantalum cap  One of six C6 on 16KB-64KB board. (+/- 12V lines).
  10586#11 flavio75 5160 Tantalum cap  
MAY08 10586#30 vwestlife 5150 Tantalum cap  64KB-256KB board. C7 nearest U5 (sits on -12V line).
MAY08 10931 dongfeng 5150 RAM  
JAN09 12623 Luke 5160 Tantalum cap  C58 (sits on -12V line).
MAR09 10931#12 tezza 5150 RAM  Last worked okay a few months previously.
MAR10 19968 rtwo 5155 BIOS ROM  U19
NOV10 22539#38 nestor 5150 RAM  64KB-256KB board. One faulty 4164 RAM chip in bank 0.
JAN11 25636 Denniske1976 5160 Tantalum cap  C56 (sits on +12V line).
FEB11 24438#1 mikey99 5150 RAM  16KB-64KB board. One faulty 4116 RAM chip in bank 3.
MAR11 24606 framer 5150 BIOS ROM  U33
MAR11 24121#17 zoomgofstr 5155 RAM  
MAY11 25602 redhawk579 5160 Tantalum cap  C56 (sits on +12V line).
AUG11 27010#8 bettablue 5150 Tantalum cap  Multiple.
DEC11   mikey99 5150 RAM  16KB-64KB board. One 4116 RAM chip. Same motherboard that failed in February.
MAY12 30899 DOS lives on 5170 RAM  Type 1 motherboard. One chip in bank 0.
MAY12 31075 CannedBread 5155 Tantalum cap  C58 (sits on -12V line)         (plus tantalum cap C8 on IBM CGA card)
JUN12 31716 latvija13 5155 2 x tantalum caps  C56 (sits on +12V line) or C58 (sits on -12V line)  -  both removed.
SEP12 33250 marcoguy 5160 RAM  No longer seeing RAM above 128 KB.  Fix: Reseated RAM chips.
OCT12 34322 madmaxamdam 5160 2 x tantalum caps  C56 (sits on +12V line) or C58 (sits on -12V line)  -  both removed.
APR13 36858#54 PCFreek 5150 RAM  64KB-256KB board. One faulty 4164 RAM chip in bank 0.
APR13 36858 PCFreek 5150 Multiple faults  16KB-64KB board #1. 74LS175 chip (U26) + faulty 4116 RAM chips.
APR13 36858 PCFreek 5150 RAM  16KB-64KB board #2. One 4116 RAM chip.
JUL13 38680 gkavner 5150 2 x tantalum caps  64KB-256KB board. Caps on +12V and -12V lines.
JUL13   PCFreek 5150 Tantalum cap  16KB-64KB board. One of many caps on +12V line.
AUG13 39067#1 eXTended8088 5160 RAM  Faulty RAM in bank 0.
AUG13 39160#12 framer 5160 Tantalum cap  C56 (sits on +12V line) or C58 (sits on -12V line)  -  both removed.
AUG13 39236 camerongray 5160 Tantalum cap  C56 (sits on +12V line).
SEP13 39617 gkavner 5150 Tantalum cap  
NOV13 40575#22 giobbi 5160 Tantalum cap  C56 (sits on +12V line).
DEC13 40956#9 tezza 5160 Tantalum caps + RAM  C56 (sits on +12V line) and C58 (sits on -12V line) and faulty RAM in bank 0.
JAN14 41168 Denniske1976 5160 2 x tantalum caps  C56 (sits on +12V line) and C58 (sits on -12V line).
JAN14 41201 VintageC 5155 Tantalum cap  C56 (sits on +12V line) or C58 (sits on -12V line)  -  both removed.
JAN14 [email] Denniske1976 5160 Tantalum cap  C56 (sits on +12V line).
FEB14 41680 commodorejohn 5150 Tantalum caps  Caps on the +12V line and -12V lines.
MAR14 42334 xave 5160 RAM  No longer seeing RAM above 64 KB.  Cause: Bad RAM chip in 64-128KB bank
MAR14 42399#8 awergh 5160 Tantalum caps  Caps on the +12V line and -12V lines.
MAR14 42467#4 bjorn_and 5150 Tantalum cap  Cap on the -12V line.
JUN14 43530 3pcedev 5160 RAM  
JUL14 43769 bobba84 5160 RAM  Via PM: "10 bad RAM chips".  5160 had been in a shed for 7 years.
AUG14 44293 PCFreek 5150 Tantalum cap  16KB-64KB board. One cap on the +12V line.
SEP14 44854#1 PCFreek 5150 Tantalum cap  16KB-64KB board #1.  One C6 (there are many C6's - used on both the -12V and +12V lines).
SEP14 44380#1 PCFreek 5150 Tantalum cap  16KB-64KB board #2.  Multiple C6 (there are many C6's - used on both the -12V and +12V lines).
SEP14 45004 codeman 5150 Tantalum cap  16KB-64KB board.
JAN15 46667 MauriceH 5160 RAM  No longer seeing RAM above 128 KB.  Cause: Bad RAM chip in 128-192KB bank
APR15 47653 Stone 5150 Tantalum cap  64KB-256KB board. The cap on the -12V line.
APR15 47795 romanon 5150 RAM  Faulty RAM in bank 0.
APR15 47041 romanon 5170 keyboard controller  Faulty keyboard controller chip (U126).
MAY15 47935 gobabushka 5155 Tantalum caps  C56 (sits on +12V line) and C68 (sits on -5V line).
MAY15 48041 framer 5160 Tantalum cap + RAM  C56 (sits on +12V line) or C58 (sits on -12V line) - both removed.  Plus faulty RAM.
MAY15 48105 Divad 5150 BIOS ROM + RAM  16KB-64KB board.  Faulty U33, plus faulty RAM in bank 0.
AUG15 49222#6 max5160 5160 BIOS ROM  Faulty U18.
AUG15 49282 vossi 5160 Tantalum cap  C56 (sits on +12V line).
AUG15 49383 Chromedome45 5150 RAM  Faulty RAM in bank 0.
SEP15   elwro07 5155 Tantalum caps  C56 (sits on +12V line) and C58 (sits on -12V line).
NOV15 50452 Gerardcjat 5155 Tantalum caps  C56 (sits on +12V line) and C58 (sits on -12V line)         (plus tantalum cap C8 on IBM CGA card)
NOV15 50398#37 A Fox 5160 IC  Faulty U27.
NOV15 50398#38 A Fox 5160 IC + RAM  Faulty U11 and U20, plus six faulty 4164.
DEC15 49773 fafonso 5150 RAM  Faulty RAM in bank 0.
DEC15 51030 Ozzuneoj 5150 RAM  Faulty RAM in bank 0.
FEB16 52017 offensive_Jerk 5150 RAM  Faulty RAM in bank 0.
APR16 52814 gleegum 5160 Tantalum cap  C56 (sits on +12V line).
APR16 52815 offensive_Jerk 5170 IC  Type 1 motherboard.  Faulty MC146818
APR16 52896 prime 5150 IC  16KB-64KB board.  Faulty U15 and U17 and U23.
APR16 52896#17 prime 5150 Tantalum cap  C7 nearest U5 (sits on -12V line).  Repaired in March.
SEP16 54728 astamp 5160 Tantalum cap  C58 (sits on -12V line).
NOV16 55848 lutiana 5170 RAM  Type 1 motherboard.  One chip in bank 0.
DEC16 56226 Flamin Joe 5150 Tantalum cap  Quote: "shorted Tantalums on the 12V rail"
JAN17 56458 offensive_Jerk 5150 Tantalum cap  Linked video showed the one on the +12V line.
MAR17 53805 gigabajcior 5170 RAM delay line  DS1010-200
MAR17 57475#39 paperinik77pk 5160 Tantalum caps + RAM  Quote: "two 12v tantalum capacitors and some bad 4164 chips"
APR17 58105 Microfinne 5160 Tantalum caps  C56 (sits on +12V line) and C58 (sits on -12V line).
MAY17 58637 RadRacer203 5150 Tantalum caps  C6 (sits on +12V line) and C7 (sits on -12V line).
NOV17 61405 KLund1 5150 Tantalum cap  
MAR18 63505 jesolo 5150 RAM  RAM related problem.
JUN18 65027 KLund1 5150 Tantalum cap  16KB-64KB board.  Quote: "C6 closest to the white power connector."  (This sits on -12V line.)
JUL18 65788 rvdbijl 5150 RAM  16KB-64KB board.  One chip in bank 0.
AUG18 66417#13 David_M 5170 Various  ROM + RAM
AUG18 66417#13 David_M 5170 Various  ROM + RAM + CPU
OCT18 67292 lutiana 5150 Various  16KB-64KB board.  ROM + RAM + [RAM refresh problem]
NOV18 67693 organizethis 5160 Tantalum cap  C58 (sits on -12V line).
DEC18   Flamin Joe 5170 IC  Type 1 motherboard.  Faulty MC146818.
JAN19 69184 mykrowyre 5155 Tantalum caps  C56 (sits on +12V line) and C58 (sits on -12V line)         (plus tantalum cap on video card)
FEB19 69192 romanon 5150 IC  16KB-64KB board.  Faulty 8237 DMA chip.
FEB19 69365 Pekopome 5155 Tantalum cap  C56 (sits on +12V line).
JUN19 71597 mrmanse 5155 Tantalum caps  C56 (sits on +12V line) and C58 (sits on -12V line).
AUG19 72246 MikeTwain 5160 Tantalum caps  C56 (sits on +12V line) and C58 (sits on -12V line).
AUG19 71730 KLund1 5150 RAM  16KB-64KB board.  Multiple faulty RAM chips in bank 0.
SEP19 72615 dabone 5150 Tantalum cap  Quote: "... and it ended up being a shorted 12v cap"
SEP19 72622 flyingji5 5170 IC  Faulty D82284-6 chip.
NOV19 49282#24 tonata 5160 Tantalum cap  C56 (sits on +12V line).
JAN20 74392 Smack2k 5160 RAM  No longer seeing RAM above 256 KB.  Cause: Bad RAM chip in 256-512KB bank
FEB20 74871 Old_hitech 5150 Various  16KB-64KB board. One cap on the +12V line, plus some yet-to-be-determined causes.
FEB20 74951 Dani G 5162 IC  Faulty MC146818.
APR20 75542 NoSmoke 5150 Tantalum cap  16KB-64KB board. One cap on the +12V line.
APR20 75771 singlethread 5160 Tantalum cap  C58 (sits on -12V line).
JUL20 77189 Gary C 5160 Tantalum cap  C56 (sits on +12V line).
JUL20 40442 Alfred Werner 5160 BIOS ROM  Faulty BIOS ROM, U18.
OCT20 79645 Carles20VT 5170 IC socket  Faulty IC socket for BIOS ROM.
NOV20   tonata 5160 Multiple  Faulty RAM, plus CPU not connecting well with its socket.
FEB21 80316#5 shirsch 5150 Tantalum cap  16KB-64KB board. One cap on the +12V line.
MAR21 80434 hkzlab 5160 IC  Faulty chip in position U24.
MAR21 80555 simmiv 5170 IC  Faulty 8254-2.
MAR21 80782 chris_nh 5150 Tantalum caps  16KB-64KB board.  Caps on the +12V and -12V lines, plus some yet-to-be-determined causes.
MAY21 1210320 jackb77 5170 Multiple  Type 1 motherboard.  Multiple problems.
JUN21 1213256 fabs0 5150 Multiple  64KB-256KB board.  Faulty RAM, plus faulty U26, plus some yet-to-be-determined causes.
JUN21 1215911 UnicycleFunStuff 5170 keyboard controller  Faulty keyboard controller chip (U126).
AUG21 1220060 Dave Farquhar 5170 RAM  Type 3 motherboard.  One chip in bank 0.  Unusual symptoms seen when IBM BIOS ROM's fitted.
AUG21 1223820 dabone 5150 PCB trace  "broken D7 trace between U12 and U13."
OCT21 1227969 1200XL M.U.L.E. 5150 Tantalum cap  64KB-256KB board. C7 nearest U5 (sits on -12V line).
OCT21 1230732#93 DrAlis 5155 Tantalum cap  C58 (sits on -12V line).
OCT21 1230732#93 DrAlis 5155 Tantalum caps  C56 (sits on +12V line) and C58 (sits on -12V line)         (plus tantalum cap C8 on IBM CGA card)
NOV21 1230732 John's first 5160 5160 Tantalum cap  C58 (sits on -12V line).
NOV21 1232972 VintageVic 5150 Tantalum cap  64KB-256KB board.  Cap on +12V line.
DEC21 1235906 Dave_88 5160 RAM delay line  Sprague 61Z14A100.
JUN22 1238935 maelstrm 5160 RAM  No longer seeing RAM above 64 KB.  Cause: Bad RAM chip in 64-128KB bank
JUL22   dmuntz 5160 Tantalum cap  C58 (sits on -12V line).
JUL22 1239263 VERAULT 5150 Tantalum cap  16KB-64KB board.  Cap on 12V line.
JUL22 1239271 Roland Huisman 5160 Tantalum cap  C56 (sits on +12V line).
AUG22 1237875 xeen 5160 Tantalum cap  C58 (sits on -12V line).
SEP22 1240145 CrashOverride 5160 Tantalum cap  C58 (sits on -12V line).
OCT22 1239139 thegenerallee86 5150 2 x tantalum caps  64KB-256KB board. Caps on +12V and -12V lines.
DEC22 1241282 johnq 5160 IC  Faulty U7 (a 74LS373).
JAN23 1241629 KLund1 5150 Tantalum cap  64KB-256KB board. Cap on the -12V line.
JAN23 1241551 lordhailsham 5160 2 x tantalum caps  C56 (sits on +12V line) and C58 (sits on -12V line).
FEB23 1241572 xavicampa 5170 Multiple  Type 1 motherboard.  Faulty MC146818, plus faulty RAM delay line (61Z14A200).
FEB23 1241880 KLund1 5150 IC  Faulty 8284A chip.
FEB23 1241826 Claude25 5150 Tantalum caps  Two tantalum caps on motherboard, plus one on a RAM expansion card.
FEB23 1242117 VeryVon 5150 Multiple  Tantalum caps, plus 8253 timer chip, plus RAM chip.
MAR23 1242242 fdiskitup 5150 Tantalum cap  16KB-64KB board.  Cap on the -12V line.
MAR23 1242274#1 appleIImidi 5150 Tantalum cap  appleIImidi's first 5150. 64KB-256KB board.  Cap on the +12V line.
MAR23 1242274#17 appleIImidi 5150 Tantalum cap  appleIImidi's second 5150. 64KB-256KB board.  Cap on the -12V line.
MAR23 1242306 Rask 5162 IC's  At least 4 faulty IC's.
APR23 1242844 hozone 5160 Tantalum caps  Caps on +12V and -12V lines.
MAY23 1242989 dabone 5150 RAM  64KB-256KB board.  One faulty 4164 RAM chip in bank 0.   See note 1 below.
MAY23 1243852 Nama 5150 IC's  64KB-256KB board.  Multiple IC's.
JUL23 1243982 Wobblestone 5160 IC  Faulty 74S74 chip at position U86.
AUG23 1244074 rglenn 5150 IC  Faulty 8284A chip.
AUG23 19870 johnq 5160 Tantalum cap  C58 (sits on -12V line).  (Post #1333544 of that very long thread.)
AUG23 1244392 Swoop2392 5160 RAM ?  No longer seeing RAM above 448 KB.  Probable (not only) cause: RAM chip.  See here.
SEP23 1243108 rodney 5170 IC's  Post #39 onwards.  Post #58 indicates many IC's replaced.
SEP23 1244646 Aptly3311 5160 2 x tantalum caps  C56 (sits on +12V line) and C58 (sits on -12V line).
OCT23 1244267 Disappearing inc 5150 Various  16KB-64KB board.  Numerous problems.  See post #40 for summary.
OCT23 1245262 Nama 5150 IC  64KB-256KB board.  Faulty U10.  Same motherboard as above (MAY23/1243852).
OCT23 1244040#73 Dave84620 5150 IC  16KB-64KB board.  RAM address problem.  Probable (not only) cause: RAM chip.
OCT23 1245345 Wobblestone 5150 IC  Faulty DMA controller chip (8237A) causing 'PARITY ERROR 1' during start-up.
NOV23 1245657 compaqportableplus 5150 Tantalum cap  Faulty tantalum capacitor.
DEC23 1245886 Skip94 5150 IC  64KB-256KB board.  Faulty U14.
DEC23 1245923 VeryVon 5150 PCB/solder  64KB-256KB board.  See post #124.
JAN24 1246363 VeryVon 5150 PCB  16KB-64KB board.  Short-circuit in PCB.
JAN24 1246400 vossi 5150 PCB  64KB-256KB board.  Small hole found drilled in PCB.    (Very weird.)
JAN24 1246461 VeryVon 5150 IC's  64KB-256KB board.  Multiple IC's.
JAN24 1246323 Piligrim05 5170 IC's  Multiple IC's.
JAN24 1246480 RDuckey 5160 RAM  Not seeing RAM above 64 KB.  Cause: Bad RAM chip/s in 64-128KB bank
FEB24 1246673 DaCiRo 5160 Tantalum cap  C58 (sits on -12V line).
FEB24 1246704 VeryVon 5150 PCB/solder  Issues under the socket that had been installed for the DMA controller chip.
FEB24 1246735 RDuckey 5160 Multiple  RAM chip, plus faulty U19 ROM.
MAR24 1247093 Oddsocks 5150 Multiple  16KB-64KB board.  Cap on a 12V line, plus RAM chips, plus ?????  {in progress repair}
MAR24 1247190 KLund1 5160 Missing jumper  256-640KB board.  Will not recognise 640K RAM.  E2 jumper found missing.
MAR24 1247500 MacGyverr 5150 Multiple  16KB-64KB board.  Multiple RAM chips, plus 8255A chip.
APR24 1247616 floogy 5160 Tantalum cap  C58 (sits on -12V line).
APR24 1247709 Frank4545 5170 ???  No-go fault disappeared.
MAY24 1248101 olegyk 5150 2 x tantalum caps  64KB-256KB board.  Tantalum capacitors on +12V and -12V lines.
MAY24 1248205 flaviosr 5160 Tantalum cap  C56 (sits on +12V line).
MAY24 1248288 RDuckey 5160 Tantalum caps + RAM  C56 (sits on +12V line) and C58 (sits on -12V line) and faulty RAM.
MAY24 1248264 docangle 5160 Crystal + cap  Crystal, plus ceramic capacitor C2.
MAY24 1245531#20 Superhik 5160 IC  Faulty U9, with the possibility of U20 as well.
MAY24 1248328 Honza 5155 IC  Faulty U68 (part of switch reading circuitry).
JUN24 1248403 ExNASATerry 5150 Multiple  16KB-64KB board.  Multiple tantalum capacitors, and a BASIC ROM.
JUN24 1248553 docangle 5150 Multiple  64KB-256KB board.  Chip U52, chip U31, plus multiple RAM chips.
JUN24 1248649 NickyDoes 5150 Multiple  64KB-256KB board.  Tantalum capacitors on +12V and -12V lines, plus ?????
JUN24 1248652 docangle 5150 RAM  64KB-256KB board.  Intermittent 'PARITY CHECK 1' error.  Motherboard RAM chips re-seated.
JUN24 1248754 docangle 5150 Multiple  64KB-256KB board.  Tantalum capacitors on +12V and -12V lines, plus U14.
JUL24 1248819 oldcomputerdave 5162 Multiple  DMA controller chip, plus ?????  {in progress repair}
JUL24 Via DM VeryVon 5155 2 x tantalum caps  C56 (sits on +12V line) and C58 (sits on -12V line).
AUG24 1249186#56 AltairNic 5155 PCB  Broken trace under socket U18.
AUG24 1249467 BlaBla1985 5150 RAM  Faulty RAM chips, including one that failed in an 'address' way.



Some of my own motherboard repairs:

Date Motherboard Cause   Comment
NOV08 5150 Faulty RAM chip  16KB-64KB board.  One faulty 4116 RAM chip in bank 0.
NOV08 5170 Faulty RAM chip  
AUG09 5150 Faulty 74LS138 chip  Thermal.  Chip worked when cold.
JAN10 5150 2 x tantalum caps plus 3 x RAM chips  Newly acquired motherboard.
FEB10 5160 RAM delay line  
OCT19 5150 Various Prior to my acquisition of the motherboard, the motherboard had had a card fitted where, many years ago, the on-card battery had leaked.
1.   Discovered some faulty chips (right next to the slots).
2.   No damaged tracks, but there were damaged vias.   Those vias were some of the many where the solder in the component side of the via had become very dull and had become concrete like (example).   Those 'some' were open-circuit.   The photo at here shows my bypassing of the damaged vias, using wire-wrap wire.
DEC21 5160 Faulty IC Discovered about 4 ohms between bits 2 and 1 of the external data bus.
Tracked down to chip U10, a 74LS670, used for the DMA page registers.
See note 2 below.
APR22 5150 IC socket 16KB-64KB board.
8088 CPU needed to be re-seated.

( I have needed to do that 3 times now.  I am on the verge of replacing the IC socket. )
AUG23 5160 Bad solder joint Started off slightly intermittent, then progressively got worse, eventually becoming permanent.
Bad solder joint on a pin of the DMA controller chip.

( This is a 'test' motherboard of mine, getting flexed often. )
AUG23 5150 Faulty IC 64KB-256KB board.
Faulty U79, causing Ruud's Diagnostic ROM to report a RAM addressing error.

( 74LS158. When removed, 13 ohms was discovered between the ground pin and pin 12. See note 2 below.)
FEB24 5150 Tantalum cap 64KB-256KB board.
This is the motherboard above in the 'OCT19' line.  It had been in storage for about, 4 years ?
At application of power, C7 (the one on the +12V line) blew open-circuit.




Note 1 The Supersoft Diagnostic ROM and Ruud's Diagnostics ROM both passed.
That was because, at the time, both were missing a test that the POST in the IBM BIOS ROM does.
That test is a look for certain RAM addressing problems.
As from version 3.3, Ruud's Diagnostic ROM now looks for RAM addressing problems.
   
Note 2 Note that most faulty chips will not have low ohmage between pins.