RISC-PC Not Working

Arc/RPCs, peripherals, RISCOS operating system & ARM kit eg GP2x, BeagleBoard
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RISC-PC Not Working

Postby BeebMaster » Sun Oct 04, 2015 12:21 pm

I'm never going on holiday again, it's taken me about half an hour to get the MDFS going again, and now I've found the RISC-PC has developed a curious problem.

The topic name was a bit vague, it powers on and I get a start-up screen, actually going to a Supervisor prompt, but that's all I can do.

It isn't:

- recognising the keyboard
- listing a filing system in the start-up message
- booting from the hard disc
- giving the Archie equivalent of the VDU7 bleep when it starts
- exercising the floppy drive
- appearing in *STATIONS from another Econet station
- appearing in my Ethernet router box's list of attached devices

On the not recognising the keyboard front, the keyboard lamps flash when the RISC-PC is powered on, or when plugging a keyboard in while it's on. I've tried two different keyboards, the same problem happens with each. If I power on with no keyboard, I get the "no keyboard detected - autobooting" message but still a Supervisor prompt.

It's like it's completely forgotten all its settings for floppy drives, hard drives, filing system, networking, boot, etc. but I can't reset it without a working keyboard!

Is there any other way to do that?
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Re: RISC-PC Not Working

Postby steve3000 » Sun Oct 04, 2015 12:57 pm

Sounds like the CMOS battery has gone flat scrambling keyboard settings etc.

Have you tried power on while holding R or Del? (these are checked before anything else, so should still be detected even if keyboard type/settings are wrong in CMOS).

If you have tried this, then open up an take a look at the PCB in case the battery has leaked?

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Re: RISC-PC Not Working

Postby steve3000 » Sun Oct 04, 2015 12:58 pm

And just in case the keyboard itself is at fault, remember you can use any PS/2 keyboard on the RiscPC :)

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Re: RISC-PC Not Working

Postby BeebMaster » Sun Oct 04, 2015 1:14 pm

DEL or R power on (or Reset) does bring it back to normal, bleeps, floppy drive life, boot into Desktop.

But it only does it on that occasion, next time after any kind of reset it is back to the Supervisor prompt and no keyboard. To use it, I have to hold down DEL or R.

I can't see the battery, there is a red and black wire coming from the points on the board marked BT1 but they disappear under the floppy drive and actually look to be going to the LEDs on the front with other wires. I'll have to take it to bits even more to find out what that is about.
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Re: RISC-PC Not Working

Postby steve3000 » Sun Oct 04, 2015 1:50 pm

BeebMaster wrote:DEL or R power on (or Reset) does bring it back to normal, bleeps, floppy drive life, boot into Desktop.

But it only does it on that occasion, next time after any kind of reset it is back to the Supervisor prompt and no keyboard. To use it, I have to hold down DEL or R.

Ok, that's a very good sign - everything's working, but the battery has gone flat, so CMOS ram isn't being retained after power off.
BeebMaster wrote:I can't see the battery, there is a red and black wire coming from the points on the board marked BT1 but they disappear under the floppy drive and actually look to be going to the LEDs on the front with other wires. I'll have to take it to bits even more to find out what that is about.

Ah, even better news - someone (presumably not you?) has relocated the battery to avoid risk of PCB damage if it leaks. Do you know if it was replaced with a rechargeable battery? If so, you just need to leave computer on for 8-12 hours to recharge, then it should keep your settings. - I'd try this first.

If it doesn't recharge after 8-12 hours, then either the battery is dead, or it's been fitted with a non-rechargeable using diode/resistor and alkaline battery (usually 2xAAs), so next you'll need to remove the lower slice and swap in a new set...

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Re: RISC-PC Not Working

Postby BeebMaster » Sun Oct 04, 2015 2:06 pm

Right, I can see it now, I didn't know you could get that bit off, I was wondering how to get underneath the floppy. Obviously I haven't been adventurous enough with dismantling the RISC-PC; probably this is why it still works!

Tom must have have replaced the battery, it's a single rechargeable AAA in a little holder right down in the depths. I'll leave it on for a bit to charge it up.

I can't reset the clock at the minute, !Alarm and TIME$ don't have any effect - is that part of the flat battery syndrome?
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Re: RISC-PC Not Working

Postby steve3000 » Sun Oct 04, 2015 6:17 pm

BeebMaster wrote:Right, I can see it now, I didn't know you could get that bit off, I was wondering how to get underneath the floppy. Obviously I haven't been adventurous enough with dismantling the RISC-PC; probably this is why it still works!

Tom must have have replaced the battery, it's a single rechargeable AAA in a little holder right down in the depths. I'll leave it on for a bit to charge it up.

Sounds like the 'usual' fix. I find the quality of rechargeable AAAs varies a lot for these low power situations - with some happily retaining enough charge for CMOS ram for months and others losing their charge in a matter of days...despite all being similar mAh rated. Presumably self-discharge is the real killer here.
BeebMaster wrote:I can't reset the clock at the minute, !Alarm and TIME$ don't have any effect - is that part of the flat battery syndrome?

It may be something spurious about the low charge level, but doesn't sound quite right. Sometimes these clocks do 'freeze' after long periods with a flat battery, but you should be able to set the clock to anything you like - just if 'frozen' then it won't increment while the computer is off - in fact I used to have a !Boot script to set my RiscPC's clock from the network when it had no battery at all - and it worked happily.

See how things are after you've charged the battery up - if the clock doesn't fix itself, then we can investigate further.

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Re: RISC-PC Not Working

Postby BeebMaster » Sun Oct 04, 2015 9:29 pm

It's gone through a few different stages today; I thought trying to set the clock was having no effect but actually it was setting the time to 7:45pm every time I tried. A bit later on I could get the time set correctly but not the date. After that I did get the right date and time through, but then I took the RISC PC away to photograph it in pieces and when I switched it on again, it was back to how it was this morning, needing a DELETE reset to get it going every time.

It seems like you can't update the CMOS settings unless the battery is charged up, because currently I'm back to not being able to change the clock, and I can't set the Econet station number either, *SETSTATION gives me a "failed to update configuration memory" error. Using *CONFIGURE appears to work, but I can't check across a reset because I have to use DELETE to get it operational.

I'm sure it'll all be all right when the battery is fully charged.

In the meantime, what setting is going wrong to stop the keyboard working?
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Re: RISC-PC Not Working

Postby BeebMaster » Sun Oct 11, 2015 4:19 pm

I can't get it to remember anything after a reset, or set the clock, or set the station number. I've changed the battery for a different, fully-charged one, I've replaced the holder with a 3 AA holder and put 3 charged batteries in that but it doesn't make any difference.

Every reset gets me back to the Supervisor prompt with keyboard not working.

Surely this can't just be a battery issue.
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Re: RISC-PC Not Working

Postby 1024MAK » Sun Oct 11, 2015 5:03 pm

Sounds like a broken PCB track...

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Re: RISC-PC Not Working

Postby BeebMaster » Sun Oct 11, 2015 7:30 pm

Yes, thinking that, I've had the board out and given a bit of a clean around the CMOS chip and one of the resistor ICs to clean off some of the green. There wasn't much damage or corrosion, but I can't test for broken tracks because I can't see any on this type of board !!!
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Re: RISC-PC Not Working

Postby 1024MAK » Sun Oct 11, 2015 7:31 pm

If one of the SMD resistors has come off the board, that will most likely be the problem :mrgreen:

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Re: RISC-PC Not Working

Postby BeebMaster » Mon Oct 12, 2015 10:11 am

It's impossible to tell with my eyes and technical ability, although I did go over the solder points of various components with the iron to see if it might enliven any bad joints.

It hasn't helped, even leaving it on overnight still sets everything back to square one as soon as I press BREAK or reset.

One thing I discovered this morning though is that I can set the clock if I set up a loop to feed in TIME$, ie.

Code: Select all

10REPEAT
20TIME$="Mon,11 Oct 2015.09:30:00"
30*TIME
40U.0


Will report the old "Tue,6th Jan 2015.19:46:00" business until about the sixth go, then the time updates correctly.

Same with *SETSTATION, I get an error the first few times but then it goes through. These settings don't survive any kind of reset though (or at least, they might do but I can't check because the keyboard doesn't work after a reset unless DELETE or R is used).

Could that be telling us anything?
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Re: RISC-PC Not Working

Postby danielj » Mon Oct 12, 2015 10:16 am

Photo of the offending area of the motherboard? (i.e. the battery bit + surroundings?) :D

d.

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Re: RISC-PC Not Working

Postby BeebMaster » Mon Oct 12, 2015 3:33 pm

Here we go, pic of relevant area of insides:
RPC.jpg

Screen illustrating the clock setting problem:
October2015a104.jpg
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Re: RISC-PC Not Working

Postby steve3000 » Mon Oct 12, 2015 8:17 pm

BeebMaster wrote:Here we go, pic of relevant area of insides

Yuk! That looks nasty :shock: - what is the residue over everything? Hard to tell, but could it be battery leakage?

Have you treated the PCB to a vinegar wash, then water, then IPA and then more water? (if not, the gradual creep of battery corrosion could be eating through tracks or chips...)

The most likely cause of the errors you're seeing is the CMOS chip having failed or one of the I2C tracks to/from the chip having failed. However... this failure usually triggers a flashing floppy drive light (POST error) on start up.

Have you seen any flashing floppy drive light codes when you switch on?

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Re: RISC-PC Not Working

Postby BeebMaster » Sat Jan 21, 2017 11:32 pm

It's fixed by and large, it had its clock chip replaced at Bolton last November and I'm just testing it now. First off the hard disc was dead, not even attempting to spin up, but a couple of minutes with the hair dryer has restored it.

There's still a bit of a problem with the clock, after any kind of reset it puts the time back to the last time entered. I don't know how it remembers the last time input and decides to go back to that every time! The funny thing is that I'm pretty certain it has only started doing this today, because the time when I first switched it on earlier was Monday 16th January, so it lost five days between November and now.

Delete-power-on didn't help and trying that SWI call to re-start the clock from the RISC OS FAQ page hasn't helped either.
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Re: RISC-PC Not Working

Postby BeebMaster » Mon Jan 23, 2017 2:56 pm

Still no luck with the clock, the time always reverts to whatever I last did with TIME$ or SYS$TIME at the next re-start no matter how it occurs.

Anyway, it's working well enough to be deemed fit to go back into service as my all-purpose Econet Ethernet file transfer station.

I was worried about the hard drive, I'd say it's definitely dying, it likes to do that thing where it's happily reading for a bit and then it goes CLUNK as if the heads have fallen off the platter, and then it carries on again. Not long left, so I've decided to replace it.

As it happens, I decommissioned an old Dell desktop PC the other week to make space (actually power socket space more than anything) for the RPi3 Ubuntu station. It had two 40GB IDE drives in, so I'm using one of these.

It's a Seagate ST340014A, and I've connected it as a slave drive in place of the CD ROM connections. HForm formatted it using the geometry it read from the drive, and it came up as an 8GB drive. I thought it must be an internal RISC OS limit, and it sounded like enough space to me, so I didn't query it originally.

It was only after the Desktop kept freezing when writing to the drive that I looked into things a bit more. I've solved the Desktop freezing issue by setting ADFSBuffers to zero - the RISC OS FAQ told me to do that (or install a patch I couldn't find) but it didn't say why it did that, I found it really curious and I'd like to know why. Using command line (eg. *COPY :4 :5 R) didn't cause a problem. FAQ also told me that R.O. 3.7 can live with drives up to 128GB.

I reformatted it a few times beforehand to see if there was some formatting problem and then I thought the geometry was up the spout. It reports 16 heads, 16383 cylinders and 63 sectors per track. At 512 bytes per sector that gives 8GB - but the manual for the whole range of drives (from 40GB up to 160GB) showed that they all have this same geometry! The only difference is number of physical heads (1 in the case of my disc, up to 4 for 160GB model) and number of platters - 1 for mine, 2 for the larger model.

Anyway, using the number of guaranteed sectors in the manual, I worked back to a cylinder count of 77545. I thought I'd better kept SPT and head count the same. I put it in HForm and it did it till it gave me an out-of-range type error at cylinder 77505, so I went again with 77500 and it formatted fine.

Unfortunately all this Large File Allocation Unit business upsets things - it insisted on a 128K LFAU size. I suspect I'll never fill up the drive so it probably doesn't matter but it offends my sense of computing efficiency that a little Obey file of a few bytes takes up a whole 128K!

Duplicating drive 4 onto drive 5 (366,646,982 bytes copied) uses up 1,718,688 K of space!!

I'll give it a few more days or weeks with both drives attached and then decommission the old one. I might also fit a 5.25" floppy drive in place of the CD-ROM.
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Re: RISC-PC Not Working

Postby BeebMaster » Sat Jan 28, 2017 4:26 pm

Actually I only waited about two hours after the previous post and then took out the old drive and reassembled with the new drive in place. I've left the fitting of a 5.25" drive for another occasion.

It's now been restored to its usual habitat under the stairs and has been treated to its own monitor.

There's no progress with the time really. It's never the correct time after a reset, but sometimes the clock has updated a few hours since last time I set it. As it's permanently connected to the internet, can I get it to read and synchronise to the internet time like the Pi (and probably all computers connected to the internet in fact) does?
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Re: RISC-PC Not Working

Postby BeebMaster » Mon Feb 27, 2017 3:43 pm

Today I think I have fixed the clock!

Periodically I have a go at resetting the time, leaving the thing on for a bit, then restarting or powering off, but it always goes back to the exact time I last fed into it. I also try that start-clock SWI call from the RISC OS FAQ regularly, and that hasn't worked either.

Today was different. Possibly I did something in a different order than usual, or possibly I was just lucky. Here's the exact process:

1. Switch on RISC PC this morning. Clock on desktop commences at 2.37pm on Sunday, 5th February 2017, as at my last TIME$ effort.
2. Leave on for a couple of hours
3. Do *CONFIGURE SOUNDDEFAULT 1 7 1 cos the bell wasn't loud enough for me (may be significant since this affects the CMOS RAM)
4. Go into BASIC and do TIME$="MON,27 FEB 2017.14:40:00"
5. *TIME reports time correctly
6. Re-start
7. Time is now 14:41 ish but date is back to 5/2/17
8. BASIC again. Set DATE, MONTH & YEAR only with TIME$
9. *TIME OK
10. Start clock with DIM clockdata% 16:!clockdata%=0:SYS &240,&A0,clockdata%,2
11.*TIME still OK
12. Restart, clock correct, switch off for 10 mins, clock correct!!!
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Re: RISC-PC Not Working

Postby BeebMaster » Mon Feb 27, 2017 3:55 pm

CURSES!!

I restarted it at 3:50 and it's gone back to 3:01 every time !!!!!
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Re: RISC-PC Not Working

Postby BeebMaster » Mon Feb 27, 2017 9:31 pm

I think I'm in a battery charging situation (although I don't really know why). I've got it to a state now where it will remember the time and date across any form of reset, as long as it's been switched on for a bit, and it will keep the clock updated accurately whilst switched off. But there comes a point where it seems to start losing time when switched off.

I've only done limited testing in the few hours since my last post but I think possibly the batteries aren't full and it needs to be on a while to charge up enough to keep going while it's switched off. If that's the case, I'm a bit surprised, because they are new rechargeable batteries which were full when I put them in earlier this year, so they shouldn't have had the opportunity to go flat yet.
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Re: RISC-PC Not Working

Postby steve3000 » Mon Feb 27, 2017 9:46 pm

BeebMaster wrote:I think I'm in a battery charging situation (although I don't really know why). I've got it to a state now where it will remember the time and date across any form of reset, as long as it's been switched on for a bit, and it will keep the clock updated accurately whilst switched off. But there comes a point where it seems to start losing time when switched off.

If the batteries are definitively full and holding charge, the clock crystal may be sticking a bit.

I found with my RiscPC, after being at in the cupboard for 10 years, once the battery damage had been fixed and a new battery fitted, the clock initially wouldn't keep time at all when switched off. The clock would loose hours overnight, and loose days over the course of a week.

Over the course of 2-3 months of regular weekend use though, the clock gradually started keeping time. Initially it several lost hours each night, but gradually this turned to 1-2 hours, and after a few months it was only losing a few minutes each night.

Is now been about 3 years since I fixed my RiscPC, and i use it less regularly now, but it's clock is back to 100% functional and I haven't had to reprogramme it for many months.

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Re: RISC-PC Not Working

Postby danielj » Mon Feb 27, 2017 9:49 pm

It's just a watch crystal, so it's pretty straight forward to replace if that's the case?

d.

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Re: RISC-PC Not Working

Postby BeebMaster » Mon Feb 27, 2017 10:02 pm

Let's see how it goes, hopefully another bit of surgery can be avoided.

I didn't say earlier, but I had it on for a few hours yesterday as well, probably about 3 hours as I was verifying the new hard drive I fitted in January, so that may have helped revitalise things a bit.

Today is definitely very much the nearest it has been to being 100% A-1 since the very first post, so I remain hopeful!
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Re: RISC-PC Not Working

Postby RobC » Tue Feb 28, 2017 5:42 pm

Don't blame you for waiting to see if it improves but your board looks in good enough condition that further work shouldn't be a problem.

[When replacing a battery, I usually check the tracks (and repair any damage with Kynar wire), then just replace the crystal and the CMOS chip as a matter of course. You can get both for less than a couple of pounds and it saves the bother of having to get the board out again later.]

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Re: RISC-PC Not Working

Postby BeebMaster » Sat Mar 04, 2017 9:52 pm

Possibly the bodge I have in my boot sequence to fool !Killer into loading may have been confusing the date sometimes, so I've just made sure the temporary date variables were unset at the end of the boot process. That seems to have helped a bit but I'll give it a few more days as up to this point it was still losing time overnight and sometimes not accepting a new time or date across a reset.

If I do replace the clock crystal, what part do I need?
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Re: RISC-PC Not Working

Postby danielj » Sat Mar 04, 2017 9:59 pm


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Re: RISC-PC Not Working

Postby BeebMaster » Sun Oct 15, 2017 8:31 am

Only 7 months later I have replaced the clock crystal and it is now back to being fully functional. Remembered the time and date overnight.

Yesterday shortly after the repair the hard drive was behaving a bit curiously, it seemed to spin down after about 2 or 3 seconds and take the same amount of time to spin up again every time a disc access was needed. It stopped doing that after a little while.

My other RISC PC (600), the extremely green one from the South-West show the other year, is doing what the other one was doing before the clock chip was replaced. It looks like the pads of the IC contacts have been more or less completely destroyed. Can it be repaired? I thought I read about a clock chip on a podule (or at least carrier board) that you might be able to build to get round battery board leakage where the damage is too bad to put in a replacement component.
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Re: RISC-PC Not Working

Postby RobC » Sun Oct 15, 2017 8:53 am

BeebMaster wrote:I thought I read about a clock chip on a podule (or at least carrier board) that you might be able to build to get round battery board leakage where the damage is too bad to put in a replacement component.

CJE make them.

You can also hire them to see if it fixes the problem:
http://www.cjemicros.co.uk/micros/individual/newprodpages/prodinfo.php?prodcode=CJE-RTCPOD-H


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