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IanJeffray wrote: ↑

Wed Mar 03, 2021 8:19 pm

This guy... hmm... oh for the want of a schematic or BOM.

From looking up the part at:
http://smdmarkingcodes.com

It looks like a 3-pin sot package with 2cs marked on it, which appears to be a BC849C transistor.

Uncommon item x 3 from this seller (name seems familiar)

https://www.ebay.co.uk/itm/Acorn-Archim ... SwFh5gP1F8

I haven't actually got a 3D printer so I haven't been able to print anything, unfortunately. Because my Minus One uses a modified expansion connector it wouldn't fit the supporting board, obviously only a similar connector would work with it. I only plug/unplug with the -1 removed. The PCB needs to ...

I've made a rough sketch of the clip I thought of, as the part that fits in the cartridge slot is 1mm thick and 2mm wide it would need a printer capable of achieving this resolution with accuracy.

The clip would fit one on each end of the cartridge slot.

It turns out the SA machine is better than I thought. It contains a 586 card... and a knackered hard disc which makes a sound like a phone ringing, loudly. Ouch. :( :o I fixed a disk like this, a Conner SCSI that worked despite the noise. I found a white deposit where the arm with the heads on cont...

I've got round to trying the Minus One and it's great that it works, I think that myelin has made something out of nothing and although it's workable there are some issues thus far. Prior to my discovery that the edge connector I'd used was the wrong way round, connecting the Minus One to the expans...

steve3000 wrote: ↑

Sun Feb 21, 2021 6:19 pm

I'll check that, thanks. I think it may just be the angle the photo was taken, but will confirm...

Sorry about that Steve, my mistake. I was watching TV when I looked at it so I think that I was distracted.

You could try flattening the capacitor legs with a hammer to make placing the capacitor easier.

BTW the upper leg of the decoupling capacitor that you've added to the Simtec ARM3/FPA board has skewed the socket pin and it doesn't look as if it's in contact properly.

The FPA11 from the auction.

It'd might be the case with a prototype that had performance issues, that an independent power supply in sync with the cpu power could make it reliable enough, engineering something like that would be the challenge IMHO.

I noticed recently an FPA11 auction on eBay from a seller in Poole, Dorset so if this is the chip, it likely came from the Plessey plant close to Poole rather than from an Acorn computer source.

As you say, not appropriate for that particular problem but worth considering for less extensive capacitor leakage problems.

'Network Expansion' refers to the on-board network socket rather than a podule, I take it?

Have you seen:

https://www.youtube.com/watch?v=vx50YtE ... xA&index=7

It's painstaking but a worthwhile solution.

A slight mistake as Ian Jeffray posted in the Post box thread :
viewtopic.php?p=303045#p303045

- it's pip3 not pip for the pyserial module.
The CPLD is now programmed so I'll be testing the Minus One on my Electron next.

I'm glad to say that the regulator was causing the problem, now the CPLD is detected and I've moved the problem on to the Python serial module.

Although I've installed the Python3-pip installer, I think it needs to be within the Python environment to work, it doesn't work in bash.

Uncommon these days :

https://www.ebay.co.uk/itm/Acorn-BBC-Ar ... Sw8UNgJe6x

If you do another PCB you should consider using a micro-SD card socket instead, much easier to solder and they locate by a couple of holes in the PCB.

Try putting the meter probes on the sockets with the cable connected, no need to power on for that.

Is the cable screen grounded to the socket shells?

The via's can only really be checked by using one end of the track on the top as a test point 1 and the track on the underside as test point 2, which is awkward.
They looked quite green before you cleaned them.

The solder on some of the FDC chip pins and the coil/ferrite bead doesn't look too good, you might need to resort to scraping carefully & fluxing prior to trying to resolder. Do you get a clock signal from the small crystal? I saw an A5000 motherboard recently that had green on traces underneath...

Thanks for the info, myelin. I'll check the voltage at the 3.3V power pin after I've desoldered and checked the regulator, I'm sure that it's causing the problem. Any info about the Minus One would be great, I've got one of walkerworks' E2P boards and also the unusual AP5 pcb I got from Dave Hitchin...

Thanks for the advice & info. I think I might have bridged PCB tracks under the regulator, I'll remove it and replace if necessary. I didn't know the 3.3V connection bypasses the regulator to the CPLD, I tried the JTAG connector & 5V power connections according to myelin's diagrams and pictu...

I think that my regulator might be the problem, neither my Xilinx cable or myelin's simple_cpld_programmer detect a CPLD. I thought that the first CPLD looked good and I checked the soldering for continuity between the pins, the only place there could be a problem is the regulator, I don't think the...

Is there a complete view of the PCB in this format, please?

download/file.php?id=65398&mode=view

I need to check my PCB connections!

I think I've done something wrong because despite changing the CPLD for a new one it isn't detected.
I'm wondering how Xilinx Lab Tools is involved, although I recall that they're necessary and I've got them in my home folder, I haven't seen any instructions about them.

The HD podule is an Acorn AKD52, probably means no on-board version.

I believe the ElkSD64 uses a version of the AP6 rom which is programmed into an XC9536XL CPLD.

Some pictures of a Pyboard compatible I recently bought.
It shows as a storage device with some files on it, the interface is access from the terminal.

I only had short header pins, standard 2.54mm header pins don't fit. The type of connector leads from Arduino kits fit them.