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  1. Replies
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    Okay so checking voltages on the 1702 sockets: ...

    Okay so checking voltages on the 1702 sockets:

    Pin 12 - VCC - +5.05V
    Pin 15 - VBB - +5.05V
    Pin 16 - VGG - -8.98V
    Pin 22 - VCC - +4.98V
    Pin 23 - VCC - +5.05V
    Pin 24 - VDD - -9V

    I think...
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    Okay, I pulled the 1702s and decided to test the...

    Okay, I pulled the 1702s and decided to test the PSU and then reconnect to the computer if nothing went sparky sparky.

    And nothing did.. was a total non-event, PSU seemed fine. So I put it all...
  3. Thread: Videobrain

    by falter
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    Yeah.. darn.. didn't switch threads properly. ...

    Yeah.. darn.. didn't switch threads properly. Sorry guys!
  4. Thread: Videobrain

    by falter
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    I cleaned up the battery terminals and plugged in...

    I cleaned up the battery terminals and plugged in two fresh AA batteries and we have -3V at pin 1. So, that's that mystery solved.

    I also pulled up the board with the serial UART on it and took a...
  5. Thread: Videobrain

    by falter
    Replies
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    I have a Videobrain and have had two Expansion...

    I have a Videobrain and have had two Expansion 1's. I had originally thought there were 100 of these or less, based on every serial number I've seen to date being below 100, but the second one I got...
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    Ok. Pin 1 to the negative battery terminal...

    Ok. Pin 1 to the negative battery terminal resistance is zero. So there does appear to be a link there.
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    As usual, I have confused things. Chuck said...

    As usual, I have confused things. Chuck said character generator... I crosswired that in my head to EPROMs. But yeah, when I did the testing I did find good continuity between the battery holder...
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    Never heard of C bias batteries. :) I'm 43.. so...

    Never heard of C bias batteries. :) I'm 43.. so I don't know if that's too young or just ignorance. :)

    I've been working on cleaning this thing up... I'm trying to figure out the 7805 voltage...
  9. Thread: Godbout G8008

    by falter
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    Godbout G8008

    Picked up one of these off Ebay for $25.00. My understanding is these are working Intel rejects that Godbout scooped up, and then printed their own part number on the blank and resold.

    Does...
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    Thanks Chuck. So you would be alright to just...

    Thanks Chuck. So you would be alright to just leave the batteries supplying -3v with the thing turned off?

    I'm going to do some testing today, hopefully not set myself on fire. Side note: I have...
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    I read the little plug wires more closely. They...

    I read the little plug wires more closely. They clearly say 'RCDR' on them, so I assume it did some mind of recording or reading to tapes
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    Well, you're on the money about the battery...

    Well, you're on the money about the battery function Chuck - I did a continuity test between one of the poles of the battery holder and pin 15 on each of the eproms (VBB) and sure enough, they link...
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    I've had some speculation of it being an RTTY...

    I've had some speculation of it being an RTTY terminal on Facebook. But that connector doesn't make sense to me.

    I suppose another possibility is that this is just a piece of a system someone put...
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    I posted this on the Facebook group but will post...

    I posted this on the Facebook group but will post it here. I finally got this 'TVT' in. Unfortunately the seller was not too careful about packing (sigh), but I don't think it took any critical...
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    Xerox 820 stuff doesn't really command much. ...

    Xerox 820 stuff doesn't really command much. Here's an 820: https://www.ebay.ca/itm/122951093951?ul_noapp=true

    And an 820-II that didn't get any bids:...
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    I'll have to look back at some auction pics. As...

    I'll have to look back at some auction pics. As I recall, they started off with the raised power 'button's, which mechanically operated but had no effect. Then they came out with the flat square,...
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    Got a nice late Apple ][ for cheap

    Picked this up on ebay for $250. I wasn't expecting much, but it turned out to be a really nice, original, late A2S1. The bottom isn't even scratched!
    ...
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    Whoops! Mistyped. And yes.. the serial in the...

    Whoops! Mistyped.

    And yes.. the serial in the last pic is 1252, so it started out as a Rev 0 anyway.
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    Rev 0 Apple 1 Case on Ebay

    Kind of a weird one..

    https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F183846706296

    Appears to be a Rev 0, with a replacement Rev 7 board. I'm confused about...
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    I wonder if they'd have any historical stuff...

    I wonder if they'd have any historical stuff kicking around the place. That's cool that they found a line of business to keep going. Sort of what like SWTPC did, although with less success.
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    Looks like the infamous b*****j is after it. The...

    Looks like the infamous b*****j is after it. The guy has bought like half a dozen of the things. It's really strange.
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    Question: Does anyone know if a Mac II would try...

    Question: Does anyone know if a Mac II would try to boot with a bad/missing video card?

    I've really been at it with this thing, checking *everything* on the board to no avail so far. It powers...
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    Homebrew TVT I picked up

    At least, I assume it's a TVT:
    ...
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    Well, video worked before whatever the original...

    Well, video worked before whatever the original problem was happened. Didn't work with the initial jumpstart efforts. And no, the Mac definitely isn't booting anything. It won't even turn on using...
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    This fellow did (I think) a pretty good...

    This fellow did (I think) a pretty good description of the power on circuit:

    https://www.downtowndougbrown.com/2015/03/explanation-of-the-macintosh-iiiix-power-onoff-circuit/

    He suggests it has...
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