BBC Model B & Acorn Electron

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BBC Model B & Acorn Electron

Postby mrad01 on Thu Mar 14, 2013 7:32 am

Some quick Buy Now action on Trade Me let me snap up these machines. The Electron goes, but the beeb seems to have a buggered PSU.

Anyone have any tips on these puppies?
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Re: BBC Model B & Acorn Electron

Postby tezza on Thu Mar 14, 2013 8:09 am

I do know the BBC PSU's are hard to work around. Everything is packed in very tightly. I know, I had to repair a cap on one once.
http://www.classic-computers.org.nz/blo ... bc-psu.htm

Did you get disk drives with them? If not there is always one of these:
http://www.classic-computers.org.nz/blo ... -drive.htm
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Re: BBC Model B & Acorn Electron

Postby mrad01 on Thu Mar 14, 2013 9:13 am

Nice!

No, just the BBC B unit by itself. Not bad condition either. Gotta love those late night listers...

I better get the bugger working first eh?
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Re: BBC Model B & Acorn Electron

Postby mrad01 on Thu Mar 14, 2013 9:05 pm

Awesome info! Thanks, I'll do a ton of research before attempting any repairs. I'll also be careful on the PSU removal.

I won't tell you I paid $50 - I paid $40! :)
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Re: BBC Model B & Acorn Electron

Postby arjoll on Thu Mar 14, 2013 9:21 pm

mrad01 wrote:I won't tell you I paid $50 - I paid $40! :)

Gutted, I've been on the lookout for a BBC for ages, they just never seem to crop up at the right price when I'm looking!
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Wishlist: BBC model B, Spectrum 48k and anything Sord.
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Re: BBC Model B & Acorn Electron

Postby Carcenomy on Thu Mar 14, 2013 9:52 pm

If you can solve the 'I don't have the box part' problem I have a Master Compact you could have arjoll?
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Re: BBC Model B & Acorn Electron

Postby arjoll on Fri Mar 15, 2013 11:03 pm

Carcenomy wrote:If you can solve the 'I don't have the box part' problem I have a Master Compact you could have arjoll?

A quick search shows I'd need to find 5V 2A - easy - but the lack of disk drive might be more of a drama. I'll put this in the "maybe" pile :D

My main reason for wanting a BBC Model B is because it's one of the computers I had exposure to as a kid - even though Cargill went straight from Apple IIes to Exzel XTs, mum was a maths teacher at Girls' High and brought a BBC home sometimes during the holidays.
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Re: BBC Model B & Acorn Electron

Postby mrad01 on Sat Mar 16, 2013 10:40 am

machinecoder wrote:
arjoll wrote:A quick search shows I'd need to find 5V 2A - easy - but the lack of disk drive might be more of a drama. I'll put this in the "maybe" pile :D


Two BBC Drives where sold on Trademe just weeks ago !!!

No Disk drive, No drama, Buy a Solid State Drive off ebay.com.au (they sell like hot cakes)

They hold 511 Floppies, and load at three times the speed, the package includes cable and an EPROM for your BBC
I purchased one as soon as my Visa Debit card arrived and cant wait for it to arrive 8) (its only days away!)
I may mount it inside a spare BBC 5.25 Disk Drive slim line case I have 8)

By the way as the BBC circuit diagrams are less than clear, the filter caps are 0.1uf and 0.01uf (I just threw that in just in case yours have shorted and unwound as they do ! I replaced the 220uf to ensure reliable starting )

Those BBC power adapters always run a little hot for my liking so I like to leave the lid unscrewed (just lift it off) and run a fan over the computer while its running :wink: (I never let my vintage computers get hot!)

Im off to play a game of "yie-ar-kung fu" now !!! (which of my BBC's share I play it on ? ) I Love BBC's !!!!


I might get into my blown PSU tomorrow if it ends up raining. I'm in for a SSD for the BBC for sure!
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Re: BBC Model B & Acorn Electron

Postby mrad01 on Sun Mar 17, 2013 7:03 pm

Crikey!! That PSU board is jammed in there alright. C2 was blown inside out. I'll replace both of those VAC capacitors while I have it out I guess.

There is a very interesting board plugged in the ROM area, I better take a closer look!
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Re: BBC Model B & Acorn Electron

Postby mrad01 on Sun Mar 17, 2013 7:25 pm

Looks like I have no spare ROM spots in my BBC - anyone know what this board is?

It has a switch which is mounted outside.

Image
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Re: BBC Model B & Acorn Electron

Postby TRS80 on Sun Mar 17, 2013 7:37 pm

It looks like a static RAM board. I have a similar board in my Model B that allows me to upload ROMS. What is the part number on the larger chips?
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Re: BBC Model B & Acorn Electron

Postby mrad01 on Sun Mar 17, 2013 7:48 pm

TRS80 wrote:It looks like a static RAM board. I have a similar board in my Model B that allows me to upload ROMS. What is the part number on the larger chips?



They have HM6264LP-15 on them...

Board has HCR RAM ISS written on it
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Re: BBC Model B & Acorn Electron

Postby tezza on Sun Mar 17, 2013 8:51 pm

Not sure what that one is, but there was a lot of third party stuff for the BEEB.
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Re: BBC Model B & Acorn Electron

Postby mrad01 on Sun Mar 17, 2013 10:05 pm

tezza wrote:Not sure what that one is, but there was a lot of third party stuff for the BEEB.


It looks to be a RAM/ROM sidewise board.

http://stardot.org.uk/forums/viewtopic.php?f=3&t=5669
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Re: BBC Model B & Acorn Electron

Postby MisJiF on Mon Mar 18, 2013 2:08 pm

If it has 6264 RAM chips on it, it will be a sideways RAM board. This can be used to load ROM images (files) into and is really useful as you don't need to replace a physical ROM everytime you want to run a different peice of ROM software. The switch is the write protect switch as some ROM images try to write back to themselves. They will not work if they detect they are in sideways RAM instead of a read only IC. Open the switch, load the ROM image and close the switch. This stops write backs and makes the ROM image think it's an actual ROM.

BBC PSUs are fiddly, but not too hard to fix and most issues are already documented.

Take a look here:
http://www.sprow.co.uk/bbc/howto.htm

Certainly ask on http://stardot.org.uk/forums/ if you have queries and check out this thread:
http://stardot.org.uk/forums/viewtopic.php?f=3&t=2190

I'm in Auckland if you need any help.

Cheers,

Mike.
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