32 bit Fault finding index

discuss the archimedes & risc pc, peripherals and risc os/risc os on pi
User avatar
1024MAK
Posts: 12780
Joined: Mon Apr 18, 2011 5:46 pm
Location: Looking forward to summer in Somerset, UK...
Contact:

32 bit Fault finding index

Post by 1024MAK »

So I thought it was about time that we had a Fault finding index for the 32 bit'ers like the 8 bit Fault finding index.

So quoting Martin B...
MartinB wrote:A frequent post topic on STH, and indeed all similar retro forums, is where someone has a hardware fault and is asking for advice on how to go about fixing it. In response there are usually plenty of helpful suggestions and/or pointers to ‘common fault’ articles such as those hosted by Sprow or Wouter.

EDIT :

In case this never goes anywhere, resources in the spirit of the approach can be found at....

For example :

http://wouter.bbcmicro.net/hardware/repair/index.html

http://www.sprow.co.uk/bbc/doctor.htm

and the zipped-up troubleshooting book mentioned in...

http://www.stardot.org.uk/forums/viewto ... 416#p43416


Thanks

Now, in the electrical goods industry (and motor vehicles, and…) there are engineers ‘bibles’, paper and electronic, which are essentially collections of actual fault fixing reports by engineers and technicians which briefly detail which action fixed a particular fault. For example, you might get a TV entry which says “Ferguson TX100 / Repeatedly trips to Standby / Replaced IC6”. These list entries tend to be short, to the point, and, importantly, don’t include actions which didn’t fix the fault, the latter phrase being the key to the success and usefulness of such an index.

As an example from our world, I’ll pick a test case I was involved in - not to blow my trumpet but because it actually demonstrates a downside of the ‘free advice’ problem! retro_junkie posted ‘Beeb not hearing tapes' and I suggested at least 6 possible causes, all valid, and I could have suggested more, but ultimately he replaced IC7 and this action fixed the fault. BeebInc also suggested some common solutions which might equally have fixed this particular snag. The valuable knowledge there then was that a failure of IC7 does really occur and that it’s a fault which can cause a loss of tape capability. The downside was that he had to wait for replies and he might have felt swamped with suggestions, some of which could be totally anecdotal and/or theoretical and would never apply in reality. That of course was just one example from probably hundreds buried in the forum, all with a similar story.

I have for a while been thinking that a similar index would be very useful for our community and it could be hosted on this very site. It needn’t be in any way complicated and would just be partitioned by machine, e.g. Beeb, Elk, Master, Arc etc., and would simply have three or four columns – Machine configuration summary, Fault Symptoms (as detailed as possible) and what action actually fixed the fault. The single most important feature of such an index is that it is free of theory, speculation and anecdotal evidence and ONLY itemises real and successful repairs.

It would of course take time to build up some useful weight but retrospective input from users is fine as long as the information is correct and is not discoloured by memory. The index would be available to all members and all incident reports would be included unless they were clearly impossible – e.g. "Standard Iss.7 BBC B / Powers up and beeps but black screen / Replaced clear plastic keystrip cover" would probably not make the index :wink:

Someone (some people) would act as a repository for reports and these would simply be technically vetted for plausibility and then added to the list. I’m only thinking of a simple three/four column text file, nothing fancy, which can be visually scanned when hunting for a solution to a problem. I doubt we’d get into thousands of entries so a database wouldn’t be necessary although end users could import it into a their preferred package as they saw fit.

So, anyone have any thoughts on this? Good idea? Bad idea?

Answers on an electronic postcard to this thread :)

Martin
So if you have fixed up an Arc, a RISC PC or anything related to 32 bit Acorn, please post the details here :wink:

If some interest is shown, we'll make the topic a sticky thread.

Mark
User avatar
DutchAcorn
Posts: 2674
Joined: Fri Mar 21, 2014 9:56 am
Location: Maarn, Netherlands
Contact:

Re: 32 bit Fault finding index

Post by DutchAcorn »

Excellent! Can I suggest the post by Piemm fixing "RAM control line failure" on an Acorn A4 by replacing electrolytic capacitors?

viewtopic.php?f=16&t=8981

I suspect leaking capacitors may be the cause of death for many A4's (now and in the future), right after the leaking battery.
Paul
Zarchos
Posts: 2355
Joined: Sun May 19, 2013 9:19 am
Location: FRANCE

Re: 32 bit Fault finding index

Post by Zarchos »

I don't know what a sticky thread is, but may I suggest creating a category in the board index ?
In the 'hardware section' :
'Repairing ...'
The same could be great also for :
'Developments' for example Munchausen's IDE for the A3010 would be there, Dave's new IDE boards too ...
Additionally in the 'software category' :
'Developments', with subcategories apps, games, demos ...
Or WIP (work in progress) if you prefer, don't ask me to choose the more relevant English words. :mrgreen:

Compared to other boards, to me there are many entries missing in the index.
Other people opinions welcome, after all it's not sure I'm right, it's just my feeling.
User avatar
danielj
Posts: 9900
Joined: Thu Oct 02, 2008 5:51 pm
Location: Manchester
Contact:

Re: 32 bit Fault finding index

Post by danielj »

That's a good suggestion, Zarchos - I'll flag it for discussion!

d.
User avatar
paulv
Posts: 3866
Joined: Tue Jan 25, 2011 6:37 pm
Location: Leicestershire
Contact:

Re: 32 bit Fault finding index

Post by paulv »

Archimedes A300/A400 & A400/1 series not starting

Symptoms:

Machine appears dead with a possible audible ticking from the PSU....

Cause:

Typically a failure of the Tantalum capacitor C37 on the A300 schematic which is the +12V line decoupling cap.

For the Archimedes A400/1 series the equivalent to C37 is C53.

Test:

To test, simply remove the cap. and power up. If it works, then perform the fix.

Fix:

To fix, replace with an 25V rated equivalent. 16V as specified in the schematic is a little on the low side. To be on the safe side, replace all three Tantalum caps highlighted.

Image

Paul
Last edited by paulv on Fri May 13, 2016 7:25 pm, edited 5 times in total.
User avatar
paulv
Posts: 3866
Joined: Tue Jan 25, 2011 6:37 pm
Location: Leicestershire
Contact:

Re: 32 bit Fault finding index

Post by paulv »

Faulty Audio on the A300 and A400 series where sound can be heard on headphones but not via the speaker.

Typically down to a couple of faulty transistors. Replace and test with BC548 functional equivalents.

Image

Paul
User avatar
paulv
Posts: 3866
Joined: Tue Jan 25, 2011 6:37 pm
Location: Leicestershire
Contact:

Re: 32 bit Fault finding index

Post by paulv »

Replacing battery holders in the A300/A400 and A400/1 series machines...

Parts required... 2 off. BX0035 http://www.bulgin.com/products/battery-holders.html

Tools required:

Soldering Iron
Drill
Pop Rivet tool
Snips

Method:

1 Drill out the old pop rivets and remove the old battery holders
2. Mount the new holders in place and fix with new pop rivets
3. Remove all wiring from old battery holders and solder to the new ones.

Results:

Image

Paul
Last edited by paulv on Fri May 13, 2016 7:17 pm, edited 1 time in total.
User avatar
paulv
Posts: 3866
Joined: Tue Jan 25, 2011 6:37 pm
Location: Leicestershire
Contact:

Re: 32 bit Fault finding index

Post by paulv »

A5000 faults due to RAM control line failures.

Reason for fault:

Leaky SMT cap damage like the Amiga's suffer from :(

What it looks like:

Image

Image

Repair:

1. cut out IC59 and then remove what remains of the legs or use a rework station to remove the IC.
2. continuity check the lines noting the available schematic has two lines mixed up...
3. repair any tracks with kynar
4. replace the capacitor with an SMT (or through hole if you haven't got an SMT rework station) capacitor
5. solder in a new 74AC138.
6. Re-assemble and test.

Paul
Last edited by paulv on Tue Aug 08, 2017 9:25 pm, edited 1 time in total.
User avatar
paulv
Posts: 3866
Joined: Tue Jan 25, 2011 6:37 pm
Location: Leicestershire
Contact:

Re: 32 bit Fault finding index

Post by paulv »

User avatar
paulv
Posts: 3866
Joined: Tue Jan 25, 2011 6:37 pm
Location: Leicestershire
Contact:

Re: 32 bit Fault finding index

Post by paulv »

RISC OS 3 POST documentation

Paul
Attachments
RISCOS-POST-AppNote225.pdf
(61.36 KiB) Downloaded 336 times
User avatar
1024MAK
Posts: 12780
Joined: Mon Apr 18, 2011 5:46 pm
Location: Looking forward to summer in Somerset, UK...
Contact:

Re: 32 bit Fault finding index

Post by 1024MAK »

Thank you Paul for all those detailed posts, excellent work and good examples for everyone =D> =D> =D>

Mark
munchausen
Posts: 168
Joined: Fri May 30, 2014 9:53 am
Contact:

Re: 32 bit Fault finding index

Post by munchausen »

This is great idea, but if there were a dedicated sub forum it would be much easier to find specific issues. Otherwise wont we will end up scrolling through one enormous thread?
JonC
Posts: 735
Joined: Wed May 14, 2014 10:19 pm
Location: Wakefield
Contact:

Re: 32 bit Fault finding index

Post by JonC »

You could use the 'Search this topic' function and put some key words in. :P
munchausen
Posts: 168
Joined: Fri May 30, 2014 9:53 am
Contact:

Re: 32 bit Fault finding index

Post by munchausen »

An index is better than a search IMO, but OK. And I applaud the effort anyway, this is a great initiative.
AndyMc1280
Posts: 963
Joined: Sat Aug 27, 2011 11:50 am
Contact:

Re: 32 bit Fault finding index

Post by AndyMc1280 »

Broken Floppy drive (or can I convert a PC drive to work with my Arc?)

http://www.chiark.greenend.org.uk/~theo ... -acorn.txt

Plus a whole load of other tasty resources from Theo Markettos

http://www.chiark.greenend.org.uk/~theo ... hdocs.html

Not my work, but I have had a floppy drive converted using the above instructions and it works fine on my A3010.
User avatar
paulv
Posts: 3866
Joined: Tue Jan 25, 2011 6:37 pm
Location: Leicestershire
Contact:

Re: 32 bit Fault finding index

Post by paulv »

My refurbished A3000 died a couple of days ago.

After 6 hours up time, I went to reboot the machine and it failed to come back. Power cycling the machine left the BenQ 912 monitor flickering between a black screen and a no connection warning screen. The floppy drive light was flashing. It returned the POST error code of 10009 which translates to "Unreadable CMOS".

So, the machine got stripped down, the multi-meter was applied to buzz out the connections and everything was good. There was no sign of corrosion and the machine was cleaned up with an new Varta battery fitted about 3 years ago. I decided to whip out the CMOS chip and replace it with a brand spanking new chip from my current stock of these now "rare at sensible prices" through hole CMOS chips.

After putting the machine back together, I powered on holding the DEL key down to clear the CMOS, then power cycled with R and T until a picture appeared on screen. From there it was a simple case of setting the config back up correctly from my on disc backup and another reboot to get the machine up and running from the IDE CF flash card and the external network card working :D

So, even after the clean up of the original damage from the battery leak from years gone by, the alkali carried on working its evil magic on the CMOS chip until three years later, it went pop.

If you're reading this and have battery damaged A3000's, it might be worth switching out the CMOS chip whilst you're doing the battery replacement/cleanup regardless of how it works and/or looks for the future.

Paul
steve3000
Posts: 2909
Joined: Sun Nov 25, 2012 12:43 am
Contact:

Re: 32 bit Fault finding index

Post by steve3000 »

Great advice Paul, and coincidentally I have just had the very same fault from my A5000 - indeed I've just been interrogating your Web pages to decode the floppy POST message :)

Another job for the weekend...
nealgs
Posts: 18
Joined: Mon Jan 25, 2016 7:47 pm
Contact:

Re: 32 bit Fault finding index

Post by nealgs »

paulv wrote:Archimedes A300/A400 & A400/1 series not starting

Symptoms:

Machine appears dead with a possible audible ticking from the PSU....

Cause:

Typically a failure of the Tantalum capacitor C37 on the A300 schematic which is the +12V line decoupling cap.

For the Archimedes A400/1 series the equivalent to C37 is C53.

Test:

To test, simply remove the cap. and power up. If it works, then perform the fix.

Fix:

To fix, replace with an 25V rated equivalent. 16V as specified in the schematic is a little on the low side. To be on the safe side, replace all three Tantalum caps highlighted.

Image

Paul
Want to says thanks to Paulv and whoever found the above as this was the cause of my A310 not starting.

I've removed it, but would like to know where can i get replacements from? Maybe an idea to include links or to replacement parts in those posts that have the need to new components etc.

keep up the great work all

Gary
User avatar
1024MAK
Posts: 12780
Joined: Mon Apr 18, 2011 5:46 pm
Location: Looking forward to summer in Somerset, UK...
Contact:

Re: 32 bit Fault finding index

Post by 1024MAK »

100uF 25V tantalum capacitors are available from:
Farnell UK

Mark
Kazzie
Posts: 1793
Joined: Sun Oct 15, 2017 8:10 pm
Location: North Wales
Contact:

Re: 32 bit Fault finding index

Post by Kazzie »

Symptom: Archimedes 420/1 displays greyscale from analog rgb output. Known to be working correctly prior to storage.

Cause: Chip creep while in storage (outdoors).

Solution: Press firmly on VIDC video chip (Arabella) to reseat it.
BBC Model B 32K issue 7, Sidewise ROM board with 16K RAM
Archimedes 420/1 upgraded to 4MB RAM, ZIDEFS with 512MB CF card
RiscPC 600 under repair
Acorn System 1 home-made replica
User avatar
tnt23
Posts: 34
Joined: Thu Jul 16, 2015 9:24 am
Location: Saint Petersburg, Russia
Contact:

Re: 32 bit Fault finding index

Post by tnt23 »

Symptom: Mouse cursor poor performance, eventually stopped moving along vertical axis.

Cause: One or both IR diodes responsible for the failing direction decay over time.

Solution: Replace the IR diode(s).

I went with Kingbright KM-4457F3C ones recommended by someone on this forum (viewtopic.php?t=12384), unfortunately it did not help. I then went to check if the matching photo transistor's output was decent enough to drive the 74LS14, and found the signal wasn't quite as good as other photo transistors' outputs. (I wish I've taken a few shots with the oscilloscope).

Knowing the KM-4457F3C is 920nm IR LED, I have picked a matching replacement available at my local shop, the BPW85B. Still no luck, the output signal was not falling low enough to flip the inverting Shmitt trigger in the 74LS14. Long story short, it turned out this particular input of 74LS14 somehow got pulled to +5V rail too hard for the opto transistor. Upon re-routing the opto transistor output to one of spare elements in 74LS14 everything worked like a charm.

Here's a couple shots showing mouse PCB with IR diode (marked as Dx) and optotransistor (marked as Qx):
photo_2018-01-05_16-45-59.jpg
The replacement I got came in a different case, hence a bit of bending involved:
photo_2018-01-05_16-45-58.jpg
Regards, Tim
User avatar
DutchAcorn
Posts: 2674
Joined: Fri Mar 21, 2014 9:56 am
Location: Maarn, Netherlands
Contact:

Re: 32 bit Fault finding index

Post by DutchAcorn »

Symptoms: Sony floppy disk drive in an A310 reporting "drive empty" error and/or disk faults, with know good disks.

Cause: Top disk drive head does not land with enough pressure on the floppy disk when inserted. The head levitates a fraction of a mm above the disk, sometimes picking up the signal, sometimes not. Carefully pressing down on the head while the drive is working makes the errors go away.

There is a small spring pulling on the head, but it will have lost some of it's strength over the years and it has to compete with the copper plate that acts as a hinge for the drive head. The copper plate has been bent upwards a little because of having no disk inserted for years and/or getting pressed up cleaning the head with a cotton bud and alcohol.

drive heads.jpg
Solution: get the pressure back on the drive head by bending back the copper plate. With no disk inserted, press carefully but firmly on the drive head assembly just next to the copper plate.

sony drive 1.jpg
BTW, I also tried to disassemble by removing the screws but it is all very, very stuck and the method described has done the job for two drives.
Paul
User avatar
paulv
Posts: 3866
Joined: Tue Jan 25, 2011 6:37 pm
Location: Leicestershire
Contact:

Re: 32 bit Fault finding index

Post by paulv »

I've updated my POST error calculator page so it can now accept a POST error code on a URL, pre-filling the calculator form which may be useful for people on stardot when helping to fix people's Arc's.

e.g.

The error code for the recent A310 which was fixed was &00020101 so the URL would be:

Code: Select all

https://www.retro-kit.co.uk/page.cfm/content/Common-RISC-OS-POST-failure-errors/?post-error=20101
Error code &20101

It'll take any hex value so works equally well with values such as error code &C009 too :-)

Paul
gazzaD
Posts: 67
Joined: Sun Jun 18, 2017 12:37 pm
Contact:

Re: 32 bit Fault finding index

Post by gazzaD »

Symptom: A3020 not starting due to Ram control line failure, control lines test OK.

Cause: Battery leakage has affected the IDE buffer ICs 46 and 45, causing link between top and bottom of data bus.
ic4645.JPG
Solution: Removing IC46 was enough to get machine to pass POST. Both ICs needed replacing before IDE interface would recognise drives.
Last edited by gazzaD on Wed Jul 31, 2019 10:52 pm, edited 1 time in total.
Gareth
gazzaD
Posts: 67
Joined: Sun Jun 18, 2017 12:37 pm
Contact:

Re: 32 bit Fault finding index

Post by gazzaD »

Symptom: A3020 reporting no keyboard present. External keyboard seen when connected to motherboard header and jumper changed. Scoping out the keyboard data line, waveform appeared inverted when driven from IC2 (line stays at 0 with occaisional +ve pulse)

Cause: Internal pull up appears to have failed in IC2

Solution: 1K resistor between kbkin and +5 volts restored communication between IC2 and the Arm250.
Last edited by gazzaD on Wed Jul 31, 2019 11:03 pm, edited 1 time in total.
Gareth
Kazzie
Posts: 1793
Joined: Sun Oct 15, 2017 8:10 pm
Location: North Wales
Contact:

Re: 32 bit Fault finding index

Post by Kazzie »

A RiscPC (issue 2 board), having already had a battery corrosion repair, suffered progressive failure of the VIDC20 chip.

Symptoms:

Early errors included a transparent column in the hourglass cursor, and periodic "turboprop" noises from the speaker for a few seconds at a time. Later faults included bad sync on all but the initial boot screen, followed by Virq POST errors, and then Virq and Sirq errors at every bootup.

Diagnosis:

Continuity of all relevant circuits was fine: reference clock, VCO, VIDC data bus through resistor packs (including RP16) and 724ACT244 buffers to the main data bus, and Vidrq/Vidak Sndrq/Sndak lines to the IOMD chip. Reference clock running OK, VCO presumed fine, but limited by a medium-bandwidth scope. The *Cdoe signal that is used to gate the '244 buffers was stuck low.

Probing inputs and outputs of IC33 with a pair of probes, I found two outputs on IC33 did not correspond to their inputs, despite the gate input being held low.

Solution:

Replaced IC33 with a new 74ACT244. Machine now boots fine :)

Relevant thread: viewtopic.php?f=16&t=19977&p=283064#p281789
BBC Model B 32K issue 7, Sidewise ROM board with 16K RAM
Archimedes 420/1 upgraded to 4MB RAM, ZIDEFS with 512MB CF card
RiscPC 600 under repair
Acorn System 1 home-made replica
User avatar
anightin
Posts: 970
Joined: Thu Aug 23, 2018 2:03 pm
Location: Cambridge UK
Contact:

Re: 32 bit Fault finding index

Post by anightin »

A3010, Main board 0194, 003 (Also applies to A3020 all versions)

Symptoms:
  • Keyboard lights up, unresponsive
  • No floppy activity
  • No POST flashes
  • (POST box monitor hardware on test connector reports no activity)
  • No screen display

Diagnosis:

No system clock input measured on ARM250 pin 4

Cause:

Faulty X4 oscillator

Solution:

Replace X4. Hard to find replacements so alternatives can be used with minor modification:

viewtopic.php?f=16&t=20772#p291719
User avatar
kppot
Posts: 148
Joined: Mon Oct 23, 2017 10:48 pm
Location: Moscow
Contact:

Re: 32 bit Fault finding index

Post by kppot »

A3000

Symptoms:

A3000 unexpectedly fall to Supervisor mode.
Assuming you already replaced the battery and cleaned the PCB.

Diagnosis:

Pretty common one - RTC clock simply dies because of age these days
Just check if there is still some sort of corrosion nearby, just in case
1. Then check the D2 diode (same reason as above)
2. If it is fine, simply replace RTC chip

Otherwise replace diode, and fire up the machine. If Supervisor still persist, goto sptep 2
After replacement your vidoe output will be fuzzy, simply hold Del key while poering on
Nice and easy fix
viewtopic.php?f=16&t=20881#p293905
rpooley
Posts: 16
Joined: Sun Jun 14, 2020 7:36 pm
Contact:

Re: 32 bit Fault finding index

Post by rpooley »

A3020, A3010, Main board

Symptoms:
Mouse connected doesn't work, plugging in and out the mouse from the mouse port exhibits slight cursor movement and occasionally random clicks that display the middle button menu.

Diagnosis:
Voltage on the side of fuse FS5 furthest from the mouse port reports 5V but after passing through the fuse the voltage is significantly lower than 5V. In my example this was 1.5V.

A less specific diagnosis is to use a USB mouse with a visible laser, connected via an adaptor if the voltage is too low the laser will not light although you will still see the symptoms reported.

Cause:
Faulty FS5 fuse.

Solution:
Replace FS5 fuse with equivalent rating: 0815,503 FUSE 250MA F 63V AC SMD
https://uk.rs-online.com/web/p/non-rese ... s/8207091/
hank yellow
Posts: 2
Joined: Sun Nov 01, 2020 5:58 am
Location: Auckland
Contact:

Re: 32 bit Fault finding index

Post by hank yellow »

A3020

Symptom: POST failing with MEMC Protection Failed and MEMC CAM Mapping Failed (&00000D49).

Cause: Broken traces from pin 13 and pin 17 of IC32.
Post Reply

Return to “32-bit acorn hardware”