BBC Micro Model B - Restoration and Upgrade Log

Demon

Demon

Demon

Soldato
Joined
22 Oct 2002
Posts
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Location
Near Cheltenham
Another one!

Item: Advertised as VV Good condition, but sold as spares/parts due to power supply 'crackling' and stated needed a recap. I paid £100 delivered for this as the condition looked right, which considering the aim is to repair, is much more preferable..

0J8h7pJh.jpg

Initial impressions - Looks very good, almost immaculate, there were some white scratches on the perspex near the speaker, but they look too white to me and found them to be paint or similar and easily came off with a bit of a damp cloth!

The plan is
- Get it working!
- Get some form of disk replacement system
- Upgrade RAM using a sideways kit
- possibly get a Rpi based co-processor for the LOLz.

Mainly I want to just restore, get a few of the classic games going and keep this one!

I'm back filling the thread with the PSU 'repair' next.
 
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So as it was reported to have a crackingly PSU and needed recapping, I had already found plenty of places selling recap kits, but with a range of PSUs used, I needed to wait until I stripped it down to see which one to order!


Opening up the 'beeb' I was greeted with a suprprise in the form of a very very clean looking PCBA!
9qOUk1ah.jpg

A quick look revealed no other ROMS but the most basic, and no drive controller, so rife for upgrading!

Next Job was looking at the PSU and figuring out which re-cap kit is required..

So took that out, stripped it down:
It too was very clean, and oddly no caps look bulged/damaged or even 'old'..
YSJVPczh.jpg


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Those appear to be the original caps as well!

I did check the Capacitance in circuit using my Tektronix DMM 870 which seems fairly good at this, and all seemed OK, non shorted, all within a few % of their value.

I checked the main board next, ensuring no shorts on the voltage rails and re-assembled.

On switching on, I got the familiar 'beep' and it sat there all happy.. I did not have anything to display the video out (arriving shortly), but I did notice a crackling noise coming through the speaker..
On googling that, I found it is a common issue that has a couple of mods that can be done.

So, I will have to get a parts list to do a full re-cap of the PSU, that might be introducing noise on to the audio, and until it's loaded/used I can't say for sure if the preivous owner though the speaker noise was psu crackling as they are next to each other..

Next steps are:
- Order all the caps for the PSU (sadly no one does a full kit for this one)
- Check the Video out and see if she's alive!
- Order an MMFS or similar, and look at GoTek or other solutions and see what is the best fit.
 
Someone has taken care of that.

I've mentioned it before but something which always amazed me was my old secondary school IT teacher knew how to make/program pin compatible breakout boards if required for all the ICs in the BBCs - no idea where he learnt that and some serious knowledge involved.
 
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adidan said:
How is that even possible?!? :eek:
Click to expand...

My old secondary school probably had a bunch which were never turned on at the time they sat on the shelf in reserve, I think eventually they gave them to one of the smaller schools in the area though even by that point they were pretty antiquated - IIRC about the time the StrongARM RISC PC was about to be launched.
 
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Tiny update, since nothing of note arrived today, and noticed I never did check if it was 'working' i.e. getting a video output!

So, I found the RGBtoiHDMI I'd ordered, I have the 'generic' set, which was a fully built unit with Raspberry Pi Zero already in it and two cables (A BBC/AMSTRAD DIN and a Speccy DIN).

I grabbed a microSD Card, unzipped the RGBtoHDMI latest release to a FAT32 formatted card, connected the HDMI to my portable screen and the DIN to the BEEB, and according to the quick start guide the Pi is powered by the Beeb which must have 5V out the RGB socket..

So switched it on, and nothing.. the Derrrr Dooot, and that was it.. nothing, no LEDs on the RGBtoHDMI, nothing on the screen...

BAH!.. I checked everything, tried contact cleaner in the RGB socket, and still nothing.

In the end, I unplugged the beeb and powered the Raspberry Pi via normal USB and that at least fired up, so I knew the uSD card was working, and ensured it was configured for a BBC...

So digging around and you always find someone with the same issue:

For anyone else that has the same issue, the power wire isn't connected on the analog BBC cable on the pre-built units so you have to power the converter separately. This is because the same cable can be used with the analog interface for both the BBC and Amstrad CPC and on the Amstrad that pin is used for the mono video output. Also there is reverse voltage protection on the analog interface so even if you powered it up via the USB connector while connected to a BBC with a fully wired cable including the power pin it wouldn't feed the USB power back into the BBC.
Click to expand...

Which is what I have, you have two choices it seems, you can with a DIN cable, connect a BBC directly to the RGBtoHDMI main board (this is called 'digital'), or you can also have the 'analog' board inbetween the RGBtoHDMI and the DIN and this allows more computers (such as Amstrad/Speccies, etc) to be connected with just a different cable.. In my case, I have the analog board inbetween, and so this explains everything.

So all it took was a USB cable to power the Pi, and BAM..
EvSZCw0h.jpg

Wow.. this RGBtoHDMI is bloody awesome.. absolutely pixel perfect output! I tried all the usual 'MODES' on the BBC quickly, tried using 'COLOUR' to change text colour, all absolutely bang on!

So, this is the point I wanted to get to! it's worth investing in the next steps..
I already knew this was a boggo standard unit, no extra ROMs, and the *HELP command confirms just the OS.

- I want to recap the PSU entirely for the sake of a couple of £ it's worth doing.
- Look at a sideways RAM upgrade (because why not!)
- Research options for getting some games going, User Port + MMFS or something, I'll start taking a look.

I will say, the Beeb really is awesome, the keyboard is excellent, it just feels right and was an absolute marvel back in its day, I count myself lucky having this at Primary/Junior school!
- Start researching the best cart/tape or drive
 
I just used the Din to Scart, as i have a CRT TV spare.. also my Sony 48" TV in my living room bizarrely still has a scart! Its ages since i upraded my BBC i think i have the micro sd device connected to the tube port , and maybe a rom chip into the main board
 
Kurgen said:
I just used the Din to Scart, as i have a CRT TV spare.. also my Sony 48" TV in my living room bizarrely still has a scart! Its ages since i upraded my BBC i think i have the micro sd device connected to the tube port , and maybe a rom chip into the main board
Click to expand...
I've just had similar mods turn up:
- DFS 1772 Hardware + ROM
- User Port Micro SD Cart adapter

And ordered the compact PiTube to allow a co-processor and run the fabled Elite 'Executive' version..
https://www.sundby.com/index.php/project/pitubedirect/

I've got a reunion with old school mates on the weekend so will have to wait until next week to fit them, but looking forward to it!
 
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