Search found 248 matches

by johnkenyon
Sat Apr 14, 2012 6:49 pm
Forum: 8-bit acorn hardware
Topic: Help Power Supply 3.5" Floppy
Replies: 17
Views: 2216

Re: Help Power Supply 3.5" Floppy

Looks like the connector to the drive only supplies +5v to the two outside pins, so assuming it's a 7805 regulator a 9v DC unregulated supply should do the trick. As far as current is concerned, find out what the drive needs (google the drive model number may help). As far as "tip positive or negati...
by johnkenyon
Mon Feb 13, 2012 4:36 pm
Forum: 32-bit acorn hardware
Topic: A5000 CMOS Replacement
Replies: 57
Views: 12003

Re: A5000 CMOS Replacement

Stupid question, but for tidiness, isn't the A5000 RTC circuit (IC, battery, + crystal) a candidate for moving lock stock and barrel to a small separate PCB with 4 wires (+5v, 0v, SDA, SCL) connected somewhere convenient on the PCB?

ISTR that all 4 are present on the podule port...

/John
by johnkenyon
Fri Oct 07, 2011 12:03 pm
Forum: 8-bit acorn hardware
Topic: SCSI Progress At Last
Replies: 46
Views: 8075

Re: SCSI Progress At Last

Erm, I've got no idea whether the AIV SCSI board is supported with Discs. Anyone know? Update. Note that all this is "in theory", and based on JGH's ADFS 1.50 disassembly... To turn an AIV SCSI adaptor into an almost ADFS compatible adaptor: Hardware changes: 1) Replace IC1 (74AS373) with a 74AS533...
by johnkenyon
Wed Oct 05, 2011 5:43 pm
Forum: 8-bit acorn hardware
Topic: SCSI Progress At Last
Replies: 46
Views: 8075

Re: SCSI Progress At Last

Erm, I've got no idea whether the AIV SCSI board is supported with Discs. Anyone know? From what I can gather (looking at the AIV and "host adaptor" schematics), the following changes would be needed to make ADFS talk to an AIV adaptor: Software fixable differences: 1) Change all I/O accesses from ...
by johnkenyon
Thu Sep 22, 2011 11:48 am
Forum: 8-bit acorn hardware
Topic: Faulty ULA on Electron
Replies: 3
Views: 842

Re: Faulty ULA on Electron

Hi there, I am trying to repair an Electron which boots with a garbled screen. From info on the net and this forum I m pretty sure it will be the ULA. However I am stuggling to find one anywhere, does anyone have one tucked away I could possibly purchased from them? As a quick, last gasp fix, try r...
by johnkenyon
Thu Jul 21, 2011 2:14 pm
Forum: 8-bit acorn hardware
Topic: reverse engineering: Econet Level 3 fileserver RTC
Replies: 7
Views: 1065

Re: reverse engineering: Econet Level 3 fileserver RTC

The results aren't that pretty - the solder side of the board is clear, but the component side is a "tad messy".
by johnkenyon
Wed Jul 20, 2011 9:25 pm
Forum: 8-bit acorn hardware
Topic: reverse engineering: Econet Level 3 fileserver RTC
Replies: 7
Views: 1065

Re: reverse engineering: Econet Level 3 fileserver RTC

The heatgun rather than the Dremel is the tool of choice for this job. From what I've exposed so far, the board contains a single IC in a 16DIP package. Unfortunately I can't read any markings off the chip, which makes life a bit more difficult. The connection to the user port is as follows: PB0 Pin...
by johnkenyon
Wed Jul 20, 2011 3:56 pm
Forum: 8-bit acorn hardware
Topic: reverse engineering: Econet Level 3 fileserver RTC
Replies: 7
Views: 1065

Re: reverse engineering: Econet Level 3 fileserver RTC

Ok so what's inside ?
Best guess its a 146818 RTC chip, a battery and other bits and pieces.
My money is on an i2c device like a PCF8583.
I might have to attack one with a Dremel over the weekend...

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