US specification BBC Micro

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Lion
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US specification BBC Micro

Post by Lion » Fri Apr 05, 2019 12:21 am

I have received what appears to be an un-UKified US specification BBC Micro. It was given to me as "not working", so I have not attempted to power it up. Is there anything I should test or do before plugging it in? (I am in the USA.)

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Hopper
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Re: US specification BBC Micro

Post by Hopper » Tue Apr 09, 2019 6:59 pm

Change the psu capacitors perhaps?
Wonder what the machines history is? has it been in the wild in the USA all this time, or was it a greyhound job that has more recently been re exported.

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Re: US specification BBC Micro

Post by fordp » Tue Apr 09, 2019 7:49 pm

I have one of those US keyboards that has never left England. It was probably a prototype!
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Re: US specification BBC Micro

Post by 1024MAK » Tue Apr 09, 2019 9:16 pm

Yeah, the main things to do before trying it are to replace C1, C2 (both X2 type) and C9.

Assuming there are no visible defects or damage, there are no other items that need to be replaced before testing.

However, after switching on, keep your hand near to the power switch just in case you need to switch off quickly.

If it works, that’s great. If not describe the symptoms and we will go from there.

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Lion
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Re: US specification BBC Micro

Post by Lion » Sun Jan 12, 2020 8:01 am

OK well it's been a few months but I finally attempted to power it up. (I got distracted.)

Nothing happened. I measured the output of the PSU and it is outputting DC - but less than 1 volt.

So that's a disappointing start.

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tricky
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Re: US specification BBC Micro

Post by tricky » Sun Jan 12, 2020 8:13 am

When you were in the PSU, did you notice if it was set for 110 or 240 vots?

And did you replace the star er cap?

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Re: US specification BBC Micro

Post by Wheel_nut » Sun Jan 12, 2020 4:12 pm

The layout of the Main Board doesn't look like it's a BBC B or B+ and the date suggests that it is one of the prototypes of the attemts to make the Beeb FAA Compliant. The grounding cables and the shielding plates are spectacular!

If you have replaced C1, C2 and C9 on the PSU, try replacing the Output Electrolytics and test it for Voltage levels without connecting it to the Main Board. With all of that shielding and grounding, it is also possible that you have a short to ground between the Main Board and the shielding plates.
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Re: US specification BBC Micro

Post by Lardo Boffin » Sun Jan 12, 2020 4:22 pm

Does it have a part number underneath?

Looks a lot like my USA Beeb (ANB09):-

viewtopic.php?f=3&t=15446&hilit=Usa#p213082
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ask_nz
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Re: US specification BBC Micro

Post by ask_nz » Fri Jan 17, 2020 9:01 am

Also makes it the earliest US Beeb serial number (UNB09) recorded (congrats Lion) - I've updated the list.

viewtopic.php?f=42&t=10849&p=134306#p134306

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