Challenge of the month - Troubleshooting?

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adrm
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Challenge of the month - Troubleshooting?

Postby adrm » Tue Sep 19, 2017 6:54 pm

This is likely a stupid idea, but maybe, just maybe, there are others who enjoy the same thing ...?

If someone has a crusty, old Beeb they don't value too much, would they be willing to create challenges with it?
I'm thinking, remove ICs, maybe even break tracks, etc. Then post it as a challenge of the month, describing the symptoms observed.

It would then be up to the forum members to ask questions and make suggestions.
The poster would then act (probe, measure, etc) and report back, until the community has figured out the problem.

People like me would not be able to contribute much in the beginning, but we'd likely learn a lot about troubleshooting a Beeb.

Of course, this all depends on a few crucial factors:
  • Does enough people find this interesting?
  • Do any experts wish to participate?
  • Does anyone have a "sacrificial lamb" Beeb?
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Boydie
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Re: Challenge of the month - Troubleshooting?

Postby Boydie » Tue Sep 19, 2017 9:40 pm

I can see a couple of problems with this.

Firstly, it presupposes why the experts provide their assistance. It may be they do it for the same reason people do crosswords - the sheer intellectual challenge and maybe to feel superior to the setter. But I doubt it. I suspect the reason is a wish to help others and preserve as many of their beloved machines as possible. Somehow, troubleshooting a deliberately-harmed machine probably carries less appeal.

The other problem is how to harm the machine? I suspect a significant amount of damage can be done, which will either never cause any symptoms (depending on peripherals, usage etc) or at best only under a limited set of circumstances. I bet there are plenty of "working" machines out there which are broken in some way, but their owners have never realised because they don't use that particular function. Either it's going to be difficult to work out exactly what symptoms are caused, or you need an expert to deliberately nobble stuff in a way they will cause problems. At which point, solving it is probably fairly trivial for the other experts.

This is somewhat close to medical simulation. Great for teaching novices how to troubleshoot stuff, but pretty mundane for the experts (except for the risk of looking silly in front of colleagues).

Besides, I bet there are enough genuine broken boards out there to keep the experts entertained and for us novices to learn from (I picked up a couple more a while back)...

And I definitely seem to have a knack of generating broken boards at an alarming rate. No need to do it deliberately - just wait for my next modification attempt!

crj
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Re: Challenge of the month - Troubleshooting?

Postby crj » Wed Sep 20, 2017 5:23 am

In general, people are good at troubleshooting not by systematically enumerating all the possibilities, but by knowing enough about the kinds of problem seen in the field to look at the likely causes first.

Breaking something random therefore takes a lot of the skill out of the exercise, turning it into a more abstract puzzle.

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DutchAcorn
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Re: Challenge of the month - Troubleshooting?

Postby DutchAcorn » Wed Sep 20, 2017 6:06 am

Boydie wrote:... I suspect the reason is a wish to help others and preserve as many of their beloved machines as possible. ...


+1!

In addition to that it is fun to learn about more failure points and it's symptoms. Again, supporting the motivation Boydie posted. Deliberate fault injection will likely not be a fault that would happen in the field, there is less of a learning factor in that respect.
Paul

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1024MAK
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Re: Challenge of the month - Troubleshooting?

Postby 1024MAK » Wed Sep 20, 2017 6:54 am

In my normal job, I'm a leader of a small team that maintains, fault finds and repairs electrical control systems. Hence in addition to tinkering with 1980s and 1990s computers and various other electronic and electrical items at home, I have a good understanding of investigating faults and failures in electric and electronic systems.

Having a working machine (or a nearly working machine, even if in a poor condition) mutilated to inflict an abstract fault does not appeal to me.

Yes, some of the 'fun' is in the chase. But the reasons for helping forum members to repair their computer also includes:
  • Helping people with a problem (it's a good feeling when the owner/person doing the work reports back that they got it working :D ),
  • It often helps other people (both registered forum members and non-members),
  • It kinda documents the problem, so that if the same fault occurs again on another machine years later, hopefully either someone will remember, or a search will find the relevant post,
  • Keeps more of these old machines going (we don't want working examples to become overpriced R@RE items on auction sites),
  • Environmentally, in general it's far better to repair equipment than to dispose of it.

In terms of actual fault finding/fault location. It is a combination of skills, knowledge, experience, understanding of the system and history. Both of the machine (by this, I mean that particular model, not necessarily that particular machine, although knowing the machines history sometimes does help) and of electronics and computer systems in general. This includes 'stock' faults (very common failures) such as 'my Beeb starting smoking and gave off an unpleasant smell'.

Bouncing ideas and suggestions around in the forum also helps as it allows other members to comment.

Computers in general, are actually tricky beasts to fault find on, as there are so many possible defects that can cause the same, or very similar symptoms. Faults that stop the CPU from running can also make it very hard to diagnose the cause of the problem. And that's when you have the machine in front of you with hundreds of pounds of test equipment hooked up to it...

And don't get me started on repetitive intermittent/erratic faults. In my job, these are the Bain of my life. You travel 20, 30 or 40 miles, only to find the system working. Then the next day, or a couple of days later, it fails again... The user asks how long to fix it and so you go looking for a tree to headbutt... :twisted:

So I don't think you will get too many replies to a post where a machine has been deliberately broken.

Mark
For a "Complete BBC Games Archive" visit www.bbcmicro.co.uk NOW!
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adrm
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Re: Challenge of the month - Troubleshooting?

Postby adrm » Wed Sep 20, 2017 8:13 am

All good points, and I suspected that would be the case.
It was a fleeting thought.

In any case, I look forward to reading more troubleshooting threads :D


Again, thanks to those who offer up their time to help with their knowledge.
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daveejhitchins
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Re: Challenge of the month - Troubleshooting?

Postby daveejhitchins » Wed Sep 20, 2017 12:34 pm

I have a project - photos later - that might, sort of, fit the bill. It's one of Mark Haysman's (RetroClinic) "I've now finished with this board" board :shock:

Dave H :lol:

p.s. I'll start a new thread when I have a few photos.

p.p.s. this will be a loooooong project :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

adrm
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Re: Challenge of the month - Troubleshooting?

Postby adrm » Wed Sep 20, 2017 1:19 pm

daveejhitchins wrote:I have a project - photos later - that might, sort of, fit the bill. It's one of Mark Haysman's (RetroClinic) "I've now finished with this board" board :shock:

Dave H :lol:

p.s. I'll start a new thread when I have a few photos.

p.p.s. this will be a loooooong project :D


Sweet! =D>
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jonb
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Re: Challenge of the month - Troubleshooting?

Postby jonb » Wed Sep 20, 2017 2:00 pm

adrm wrote:In any case, I look forward to reading more troubleshooting threads :D


Yeah.. there's enough busted pooters to go round I am sure.

Will soon be resurrecting the Superbrain threads (starting with the single board - done). I've had a rest from them as they are frustratingly annoying, but I need to "get back on the horse"! These pooters ain't gonna fix 'emselves ya know!

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1024MAK
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Re: Challenge of the month - Troubleshooting?

Postby 1024MAK » Wed Sep 20, 2017 4:44 pm

daveejhitchins wrote:I have a project - photos later - that might, sort of, fit the bill. It's one of Mark Haysman's (RetroClinic) "I've now finished with this board" board :shock:

Dave H :lol:

p.s. I'll start a new thread when I have a few photos.

p.p.s. this will be a loooooong project :D


Do you need to borrow my loooooong tape measure :lol:

Mark
For a "Complete BBC Games Archive" visit www.bbcmicro.co.uk NOW!
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daveejhitchins
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Re: Challenge of the month - Troubleshooting?

Postby daveejhitchins » Wed Sep 20, 2017 7:42 pm

1024MAK wrote:Do you need to borrow my loooooong tape measure :lol:
Only if it can measure in Light Years 8)

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

KenLowe
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Re: Challenge of the month - Troubleshooting?

Postby KenLowe » Thu Sep 21, 2017 6:13 pm

daveejhitchins wrote:I have a project - photos later - that might, sort of, fit the bill. It's one of Mark Haysman's (RetroClinic) "I've now finished with this board" board :shock:

Dave H :lol:

p.s. I'll start a new thread when I have a few photos.

p.p.s. this will be a loooooong project :D


I'm intrigued!

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daveejhitchins
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Re: Challenge of the month - Troubleshooting?

Postby daveejhitchins » Fri Sep 22, 2017 7:13 pm

OK, here's a photo of the patient . . . I won't be working on it 'full-time' - so I'll post here when I get some work done. I think the first job I'll do is to remove all the ICs and IC sockets. Clean the board and fit all new IC sockets. I'll also be checking for any damage.

Dave H :D

IMG_2051.jpg

And here's a higher quality version:
IMG_2051.JPG.zip
(4.21 MiB) Downloaded 26 times
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

crj
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Re: Challenge of the month - Troubleshooting?

Postby crj » Fri Sep 22, 2017 11:53 pm

Well, I'd say some of the problems with that board would be suitable for novice-level troubleshooters. (-8

I'd not noticed the "Bob's board" under the 6502 before. Despite having lifted a few over the years. Gosh!

It also looks like they were keeping their options open to use edge connectors instead right-angled headers for all the expansion sockets under the keyboard. I thought I knew the BBC Micro back to front; it seems there are still things to learn three decades on.

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1024MAK
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Re: Challenge of the month - Troubleshooting?

Postby 1024MAK » Sat Sep 23, 2017 9:26 am

The "edge-connectors" are clearly visible on photos of model A boards.

I'm not sure whether these "edge-connector" pads were intended as edge-connector contacts, or for straight pin headers (or some other connector) fitted at 90o to the board.

Mark
For a "Complete BBC Games Archive" visit www.bbcmicro.co.uk NOW!
BeebWiki‬ - for answers to many questions...

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DutchAcorn
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Re: Challenge of the month - Troubleshooting?

Postby DutchAcorn » Sat Sep 23, 2017 12:50 pm

daveejhitchins wrote:... I think the first job I'll do is to remove all the ICs and IC sockets. Clean the board and fit all new IC sockets...

Yea, get rid of the bird shit next to IC72. :D
Paul

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daveejhitchins
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Re: Challenge of the month - Troubleshooting?

Postby daveejhitchins » Sat Sep 23, 2017 6:56 pm

DutchAcorn wrote:Yea, get rid of the bird shit next to IC72. :D
Hmmm! Does look a little nasty.

Is there a Bill of Materials for the Beeb? That would certainly help.

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com

adrm
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Re: Challenge of the month - Troubleshooting?

Postby adrm » Sat Sep 23, 2017 8:18 pm

daveejhitchins wrote: I think the first job I'll do is to remove all the ICs and IC sockets.

Dave H :D



Would there be any chance of you recording a video on your desoldering and removal work?
Considering the problems I had removing just a small IC, it would be very useful to see someone else's workflow.

(Yes, I know there are desoldering videos on YouTube already, but it would be great to see work on an actual BBC board)
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Tore

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daveejhitchins
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Re: Challenge of the month - Troubleshooting?

Postby daveejhitchins » Sat Sep 23, 2017 8:59 pm

adrm wrote:Would there be any chance of you recording a video on your desoldering and removal work?
OK, I'll pop the videos on YouTube - It seems I have a subscriber already - My MGC add. linked from the MGC on eBay :shock: \:D/

Dave H :D
Parts: UM6502CE, GAL22V10D, GAL16V8D, AS6C62256A, TC514400AZ, WD1772, R6522, TMS27C512, AT28C256
Products: ARA II, ABR, ATI, AP6, MGC, AP5 . . .
For a price list, contact me at: Retro Hardware AT dave ej hitchins DOT plus DOT com


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