Issue 3 in a Viglen Case - not working -

discuss both original and modern hardware for the bbc micro/electron
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Bitstik
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Issue 3 in a Viglen Case - not working -

Post by Bitstik »

62662341706__E7970210-069E-4A69-9917-CDD9BB82CCB6.JPG
Hi all,
It's been a long time since I've been on the forums - glad to see they are as busy as ever.

With a bit of time on my hands I've been working through some of the old projects I had put on a shelf. This is one of them..




It's an Issue 3 I bought many years ago in a non-working state. Turn on the power and one long beep and absolutely no image on a TV via standard tv output , caps lock led lights- I need to dig out my RGB to Scart cable....


From looking at various fault finding pages etc. (Sprow's webpages and this site) -
If I had a flashing cursor then I need to check keyboard connector and OS chip seated firmly.

I don't have any output but a look at the circuitboard seems to show:
1. I've got no OS or language ROM
2. I don't seem to have an ADC chip

I also note that I've got one of the old ULA chips that radiated more heat than a Nuclear PWR so it's got a heatsink - I wonder if that is the source of all my troubles?

First plan is to locate and install an OS Rom to see if I can get any image but I'm not hopeful

My fear is that something major has gone on the board which is why the PO removed the various ROMs...

If I get this working then the plan is to install a 3.5" FDD in one of the 5 1/4 openings at the front of the Viglen case, with a Gotek in the other.

thank you in advance for any thoughts you might have
I'm trying to locate an old pdf I once had which was an 88 page field guide to fault finding in the BBC.
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Bitstik
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Re: Issue 3 in a Viglen Case - not working -

Post by Bitstik »

I've found the guides I was looking for - One from Paisley College of Technology and the other is an Acorn BBC Service manual. Some bedtime reading for me
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MartinB
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Re: Issue 3 in a Viglen Case - not working -

Post by MartinB »

Missing OS and Basic roms is very often due to someone removing a previously fitted rom expansion board (e.g. ATPL) to which the missing roms will have been transferred on initial fitting. If the removal is subsequently done in ignorance of the technicalities, the devices sadly become parted from the machine leaving the latter crippled and lifeless. You will often see such rom expansion boards for sale on eBay and the like with the board being still populated with an OS and Basic rom where said chips actually belong in the machine from which the board has been removed.

Edit : In fact, the missing ADC chip 100% confirms what I'm suggesting and it was indeed an ATPL board because it also hosts that chip.
e668ecp
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Re: Issue 3 in a Viglen Case - not working -

Post by e668ecp »

I can supply you with an OS and Basic ROM if you want... just PM me
Bitstik
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Re: Issue 3 in a Viglen Case - not working -

Post by Bitstik »

Forget sherlock holmes - you chaps are the business! That would explain it and gives me some hope it's not necessarily a duff board.

Many thanks PM sent!
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MartinB
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Re: Issue 3 in a Viglen Case - not working -

Post by MartinB »

When you get new OS and Basic roms, you can attempt to fire up your machine - you don't need an ADC chip unless you want to use joysticks. However, one additional residual from the shoddy ATPL removal is likely to be incorrect motherboard links. The pic below shows the link specifics for fitting an ATPL to a Beeb so make sure your links are as per the picture before the removal of the lower S21 link.

ATPL Links.PNG
Bitstik
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Re: Issue 3 in a Viglen Case - not working -

Post by Bitstik »

SITREP-

Encouraged by the words of advice that this might have been a clumsy sideways ram board removal I dug into my stores.

I can't locate half of the things I thought I had but I did unearth an issue 2 BBC! Dead as a dodo so I think I need new magic smoke for that one.

As a temporary measure I borrowed the OS and language roms from the Issue 2 - fingers crossed and turned on - booo-beeepp- Yay but still no picture.

Checked the links and yes, you guessed, S21 not connected so I stole the link from the issue 2 - what are the odds I'll forget that I've done this and that will be another issue to "fix" when I try to get that up and running.

Turned on- Booo-beep but still no video output.

Whilst in there I changed the ULA with heatsink (and thermal paste way past its sell-by) with the ULA in the issue 2 that has no heat sink
Boo-beep but still no video.

Need to track down my rgb to scart cable to see if that output works...
At least I'm making some progress but back to the book to check the socketed ic's as recommended.

Thanks again
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Bobbi
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Re: Issue 3 in a Viglen Case - not working -

Post by Bobbi »

You have some super early machines there. Look after the Issue 2, they are not too common.
Bitstik
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Re: Issue 3 in a Viglen Case - not working -

Post by Bitstik »

I'm an idiot.

Losing faith in the scart lead I tried an old TV cable. Of course - what a muppet- I was trying to feed a video signal from a UHF output. It was never going to work...Please don't tell anyone.

Picture is very poor- rolling and I can't fine tune the tv- time to try the adjustment pot on the UHF output- waiting for a new RGB Scart cable.
But, I can see the display so the machine seems to be working.

Thank you very much.
Bitstik
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Re: Issue 3 in a Viglen Case - not working -

Post by Bitstik »

Bobbi wrote:
Tue Nov 10, 2020 7:28 pm
You have some super early machines there. Look after the Issue 2, they are not too common.
Yes, I don't know when I got that or from where. I don't think it has ever worked in my ownership - I'll be putting the ROMs back when replacements arrive. It has "reset" printed on the back cover and the cover has been pushed out so I presume a reset button was fitted at one point but there is nothing there anymore.
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Bobbi
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Re: Issue 3 in a Viglen Case - not working -

Post by Bobbi »

All the issues have a space for a reset button but was never fitted from factory apparently.
Bitstik
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Re: Issue 3 in a Viglen Case - not working -

Post by Bitstik »

I thougt you all deserved an update.

With RGB/UHF/Composite outputs all showing problems at boot (Generally very faint text/distorted text) I did what any self-respecting enthusiast would do and didn't try to find the source but added another area of potential failure to the chain!

As I have the correct RGB/Scart cable with resistors in I tried various mods as suggested through these pages in case the TV was not accepting RGB - I tried using RGB to HDMI Scart interfaces but they showed the same problem.

I purchased an 8220 RGB/VGA board from ebay to see what would happen.
After wiring it up I got this
IMG_8873 2.JPG
Reverse text with a lot of snow. I knew there might be some white pixels from reading previous posts but the reverse text intrigued me.
Now I could, at least, read the screen I tested a few modes.
Modes 0-6 worked perfectly with colour showing ok - text was clear and no white pixels

It will be obvious to others on here but I thought...hmm...issue with Teletext video.....
A quick google led me to this on the wiki - http://beebwiki.mdfs.net/Video_ULA

I could say that I undesrstood all of the text but that would not be true. I did, however, see a mention of S26 - tried fiddling with that but no luck.

I then remembered I had replaced the ULA (remember earlier??) - so I cleaned up the old ULA, put new paste on, put old heatsink on and powered up. NO change until I shifted the S26 link (back to where it originally was)

YIPPEEEE
IMG_8874.JPG
That is actually a later picture as, by then, I had installed Mark's (Retroclinic) 1770 upgrade. I'd had an 8271 fitted in this (by a PO) but it wasn't playing with 3.5" FDD.

To rule out an issue with the 3 FDD I had tried I thought I'd install Mark's Gotek kit - all powered up but hanging on *.

I contacted Mark and he responded very quickly out of hours - amongst a number of suggestions he mentioned it might be an NMI issue. I'd heard of NFI (Not Flipping Invited - "Are you going to Peter's barbeque? No, NFI" before but not NMI.

Quick google led me to http://chrisacorns.computinghistory.org ... 5_Sec1.pdf

A few mentions of NMI and then, on page 28

" vi) On issue 1, 2 or 3 circuit boards only, cut the leg of IC27 pin 9 as close to the PCB as possible and the track connected to it on the component side of the circuit board between IC27 and IC89, then reconnect the cut IC leg to the East pad of link S9 with a short Length of insulated wire.vii)"

Hmm. Some idiot, on installing the 1770, had misread the "cut link" to "cut the blue wire attached to that chip on the left" - Fortunately I'd cut the wire at the solder join so a quick bit of soldering had it fixed and all sytems go.
IMG_8878 2.JPG
As I went to email Mark I noticed he'd already diagnosed this issue from afar... I thanked him and apologised for being a half-wit.

First game loaded from the Gotek? Had to be Frak!

Now to put the beastie back together
Bitstik
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Re: Issue 3 in a Viglen Case - not working -

Post by Bitstik »

The Viglen case just replaces the top half of the BBC B with two 5/1/4 drive bays supported by a steel panel- there is another steel panel on the underside of the lid to give the case some support for a monitor on top.
This is the panel with the first of two 5.25 to 3.5" adaptors installed -
IMG_8879.JPG
There is a screwhead which requires one of the adaptors to be modified with a dremel to fit.

Of course, after I fitted the Gotek and 3.5" respectively into their holders and screwed up to the panel I realised the Gotek is set as Drive 0/2 and the FDD is 1 and 3. Guess which way round I'd fitted them on the panel...


A quick reshuffle later and they were all installed. Lid back on and it looks like this

IMG_8880.JPG
I tried to make an extension lead from the ribbon cable but (somehow) the IDC plug I bought, whilst fitting in the second socket on the cable, is incredibly loose. The pins seem too thin...I've got a replacement on order so for the moment only the Gotek is wired up.

Next games tested:
Escape from Moonbase Alpha - one of the few games I completed back in the day

Citadel - need i say any more

Labyrinthe - a curious game I'd not seen before- involves pushing a rock from room to room and shooting enemies/squashing with rock. If the rock is pushed against a wall it rebounds and takes some health. I'll have another look at this one.

Snake

Zalaga

Enhanced Frak! - couldn't see what was enhanced but I do recall one version back in the day that said rude things.

That's all the extensive testing done for the moment.

To do:
Install stereo (mono) switched output socket and volume control
Find a replacement for the Zif socket that no longer works - I think Mark did a version some time ago
Consider a pi processor
Look at installing the sideways rom/ram board I bought some time ago.
Tidy up the keyboard case- Need to find/make a keboard overlay.
Fit the rgb-hdmi adaptor when it arrives

Thanks for the help - this board is a treasure trove of info.
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