Another loft refugee to be rescued!

discuss both original and modern hardware for the bbc micro/electron
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roobarb!
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Another loft refugee to be rescued!

Post by roobarb! » Fri Mar 27, 2020 1:40 pm

Hey everyone, hope you're keeping well.

Mentioned in my intro post, I've recently inherited my Dad's BBC B, which I used to spend a fair amount of time using. Now that my daughter is about the same age as when I started messing around with it and she's shown an interest in "the computer with the red keys", I'd love to have it in a stable condition for her to play all the great games and educational content while we're cooped up. And maybe because I'll find it fun too... ;)

I've grabbed the Turbo MMC from IFEL's eBay page (remarkably fast shipping, thank you, Steve) fitted it with no issues, but remembered my Dad saying "I've had to take out that I/O chip", which of course, is the IC69 6522. No Turbo MMC without that and the old chip is definitely dead - swapping with the system VIA disabled the keyboard and sent the thing into a frenzy, through which I could just make out 'Turbo MMC' on the screen, so I know the new part is not at fault.

So my first big ask - I've ordered some 6522s which will take quite some time to arrive, but would anybody here be able to provide one so I can get this up and running? Now I absolutely do not want anybody making a special trip given the circumstances (and the very sensible closure of the Wanted forum) but if you happen to have one, happen to have a stamp and an envelope and happen to be passing a post box on your Government Mandated Exercise Period, I would be very grateful and more than happy to cover all costs.

The second problem is the keyboard - for some reason 'Z' is not happy and the advice to press it 50 times or so has yielded no joy. All other keys are fine and solder joints look good, so it's definitely just that one. Is there a guide anywhere as to the best way of resurrecting individual keys?

This post is verbose enough, so thank you all in advance. Take care!
BBC Model B - 32K, Issue 4, IFEL RAM/ROM, Speech System, Turbo MMC
A3010 - Unknown condition, hiding in the loft!
Risc PC - Fine last time I saw it!

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tricky
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Re: Another loft refugee to be rescued!

Post by tricky » Fri Mar 27, 2020 1:53 pm

I don't know about a guide, bu I have seen a few threads on here.
I do have some spare 6522s (untested from China) somewhere if no one has one to hand.
I think you should be OK pulling the key cap and trying some switch cleaner, if it is plastic safe anyway.
Next thing it to desolder one leg, unscrew (part twist, part pull - steep thread) clean and replace before trying the other.
You don't need to re-solder if you can check with a meter, because after repeating on the second leg, it will be disassembly time.
The is a thread here about programs to type into unattended beebs and you can look at the best tweets sent to the bbctweetbot (name?) if you want something short that looks nice to try out.

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daveejhitchins
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Re: Another loft refugee to be rescued!

Post by daveejhitchins » Fri Mar 27, 2020 4:30 pm

roobarb! wrote:
Fri Mar 27, 2020 1:40 pm
So my first big ask - I've ordered some 6522s which will take quite some time to arrive, but would anybody here be able to provide one so I can get this up and running? Now I absolutely do not want anybody making a special trip given the circumstances (and the very sensible closure of the Wanted forum) but if you happen to have one, happen to have a stamp and an envelope and happen to be passing a post box on your Government Mandated Exercise Period, I would be very grateful and more than happy to cover all costs.
PM sent re the 6522 . . .

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

roobarb!
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Re: Another loft refugee to be rescued!

Post by roobarb! » Fri Mar 27, 2020 7:55 pm

Thanks to you both! Dave, an email has been sent your way!

I shall try the old switch cleaner method and see where I end up. Hopefully that will be sufficient.
BBC Model B - 32K, Issue 4, IFEL RAM/ROM, Speech System, Turbo MMC
A3010 - Unknown condition, hiding in the loft!
Risc PC - Fine last time I saw it!

Kazzie
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Re: Another loft refugee to be rescued!

Post by Kazzie » Fri Mar 27, 2020 8:49 pm

If you don't want to go down pulling the keycap off, hammering away for a little longer could be an option. I've known stubborn keys to require a few hundred presses to get them working reliably again. The good thing is that they're built to take that kind of hammering. :)
BBC Model B 32k issue 7, Sidewise ROM board with 16K RAM
Archimedes 420/1 upgraded to 4MB RAM, ZIDEFS with 512MB CF card
Acorn System 1 home-made replica

WrightStuff
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Re: Another loft refugee to be rescued!

Post by WrightStuff » Fri Mar 27, 2020 9:35 pm

This might help if the key is truly dead and you need a replacement :

http://www.cjemicros.co.uk/micros/indiv ... O-BBCKS-TB

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Wheel_nut
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Re: Another loft refugee to be rescued!

Post by Wheel_nut » Fri Mar 27, 2020 10:10 pm

WrightStuff wrote:
Fri Mar 27, 2020 9:35 pm
This might help if the key is truly dead and you need a replacement :

http://www.cjemicros.co.uk/micros/indiv ... O-BBCKS-TB
Mark at RetroClinic will supply you with a replacement Keyswitch at a much lesser Ransom.

But remember that the Keyswitches are fully serviceable and will last forever. :D
#1 BBC Model B Issue 7 + 1770 DFS + Dual TEAC Floppy
#2 BBC Model B Issue 7 + 8271 DFS + Dual Floppy + Speech + PiTubeDirect on KenLowe's Tube Level Shifter
#3 BBC Model B Issue 7 + 8271 DFS + Cumana Single Floppy

roobarb!
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Re: Another loft refugee to be rescued!

Post by roobarb! » Sun Apr 12, 2020 2:07 am

Thanks, folks - switch cleaner and setting the four-year-old into hammer mode got the 'Z' key back up and running. :)
BBC Model B - 32K, Issue 4, IFEL RAM/ROM, Speech System, Turbo MMC
A3010 - Unknown condition, hiding in the loft!
Risc PC - Fine last time I saw it!

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