Identification of small Electron PCB

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retroclinic
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Identification of small Electron PCB

Post by retroclinic » Wed Feb 06, 2013 9:53 am

Dave, can you confirm the picture of the 1770 DFS board please? I can't quite see how that could be a 1770 Disc interface? I would be interested in taking any 1770 DFS PCBs for the Model B that were available.

Thx, Mark.
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danielj
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Re: FS: Slogger PCBs: Pegasus, Click, Stop Press, DFS

Post by danielj » Wed Feb 06, 2013 11:44 am

Arcadian wrote:All four PCB requests replied to via PM.

Mark - I'm by no means 100% on the boards marked '1770' so I'll take a pic and post it to a new thread for comments/observation.
Just looking at that board, it looks like it's designed to shove some edge connector signals through a buffer IC. I don't have the elk edge connector diagram to hand at the moment... Possibly something else to do with the Plus 2? Does anyone have a "last edition" slogger catalogue scanned somewhere?

d.

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Re: FS: Slogger PCBs: Pegasus, Click, Stop Press, DFS

Post by aerworuld » Wed Feb 06, 2013 1:07 pm

danielj wrote:Just looking at that board, it looks like it's designed to shove some edge connector signals through a buffer IC. I don't have the elk edge connector diagram to hand at the moment... Possibly something else to do with the Plus 2? Does anyone have a "last edition" slogger catalogue scanned somewhere?

d.
Might that account for the last IC sockets (U3 and U4) as yet unknown on the Plus 2?

Stuart :)

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danielj
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Re: FS: Slogger PCBs: Pegasus, Click, Stop Press, DFS

Post by danielj » Wed Feb 06, 2013 2:16 pm

aerworuld wrote:
danielj wrote:Just looking at that board, it looks like it's designed to shove some edge connector signals through a buffer IC. I don't have the elk edge connector diagram to hand at the moment... Possibly something else to do with the Plus 2? Does anyone have a "last edition" slogger catalogue scanned somewhere?

d.
Might that account for the last IC sockets (U3 and U4) as yet unknown on the Plus 2?

Stuart :)
Don't think so. It's a bit odd, it has 14 direct through signals (address lines?), 4 that go through the buffer and then GND & +ve and two more. 22-way is half a cartridge slot. You'd need two of them to buffer the data lines on a cartridge slot, but if that's what it's for it's a very messy way of doing it - the data lines aren't neatly lined up on each half either. Strange.

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Re: FS: Slogger PCBs: Pegasus, Click, Stop Press, DFS

Post by Prime » Wed Feb 06, 2013 3:42 pm

danielj wrote: Just looking at that board, it looks like it's designed to shove some edge connector signals through a buffer IC. I don't have the elk edge connector diagram to hand at the moment... Possibly something else to do with the Plus 2? Does anyone have a "last edition" slogger catalogue scanned somewhere?
I think it's probably an Electron keyboard buffer, that has 22 lines, of which 4 are connected to the data bus, plus I have seen pictures of electrons with a buffer in, ISTR Arcadian's Merlin Electron had a buffer.

Having a look at the Electron schematic on mdfs.net pins 5-8 of the keyboard connector are the data lines which seem to go to the chip, pin 4 which is +5V also seems to go to one of the end pins of the chip, which would make sense.

So at a guess buffering the databus perhaps ?

Cheers.

Phill.

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MartinB
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Re: FS: Slogger PCBs: Pegasus, Click, Stop Press, DFS

Post by MartinB » Wed Feb 06, 2013 5:55 pm

Daniel wrote:...shove some edge connector signals through a buffer IC.
The signal tracking and power connections are compatible with an LS244 buffer if fitted on the plain side of the PCB with Pin 1 facing forwards on the photo.

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Arcadian
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Re: Identification of small Electron PCB

Post by Arcadian » Wed Feb 06, 2013 6:11 pm

Have split the topic from the original thread in the For Sale forum.

This is the board that we're trying to identify (I'll get a better photo soon):
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flynnjs
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Re: Identification of small Electron PCB

Post by flynnjs » Wed Feb 06, 2013 7:11 pm

Confirm what Martin said. '244 buffer works fits.
Buffers just 4 lines and the /OE line is tied low
meaning they're always driving.

Someone either needed to clean up some signals
(the 244 is Schmitt) or needed more output
current.

This looks more of a "bodge/fix board" than something
that would be used in production.

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Re: Identification of small Electron PCB

Post by BeebMaster » Wed Feb 06, 2013 9:50 pm

Looks like a nit comb to me, are you sure it's a PCB?
Image

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danielj
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Re: Identification of small Electron PCB

Post by danielj » Wed Feb 06, 2013 10:06 pm

Here you go, Phill's right. It's a keyboard buffer for the RX:

Code: Select all

Popular 'PC' style design is predominant, with the original Electron keyboard and case which will retain both the speaker and the Master RAM Board switch, remote from the main RX unit on a generous length of ready made and buffered keyboard cable.
d.

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Re: Identification of small Electron PCB

Post by Slo » Thu Feb 07, 2013 11:52 am

BeebMaster wrote:Looks like a nit comb to me, are you sure it's a PCB?
:lol: [-X

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