The Craftmans Shop > New from Old
The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)
mc:
As Ade says, the Arduino IDE is pretty dated, but it's functional.
An alternative for reading .md files, is Notepad++
It's quite a handy text editor, and I have it installed on most of my computers.
awemawson:
Well never mind, I'm pretty dated myself (72 on Monday) :clap:
awemawson:
A bit more progress. I have rigged up +5 volt power to both faulty RAM cards, proved that they are not drawing excess current, and rigged a second supply up to emulate the back up battery (set at 3.7 volts)
This has allowed me to prove that the low battery alarm circuit on both cards is working correctly (+5 volt for Battery OK, close to zero for low battery).
Card #1 has a 'transition voltage' for the battery alarm exactly at the calculated 2.8 volts, but card #2 has a trigger point of 3 volts. I don't think that this has any significance but we may see later that that's a false assumption!
The bread board having arrived has let me think a bit more about the physical side of further testing, or rather oscilloscope probing of the board under test. As most components are SMD's, unlike through hole devices you need to be able to probe both sides of the PCB. This dictates that either I stand the board vertically (which makes getting at it a pain) or have the board connector hanging off one end of the breadboard.
I've chosen the later method but this has persuaded me to incorporate header pins to connect to the Arduino rather than as I had previously intended - using directly soldered flying leads. My drawer of rows of header pins is a bit on the low side so an order has been placed with RS.
Muzzerboy:
Wow I just spotted the Weir Minireg there and I must have missed the post you did about it last year. https://www.madmodder.net/index.php?topic=12909.0. Stud diodes, germanium transistors, hand wired chassis.....
I started out at Farnell Instruments (SMPS group) latterly Farnell Advance Power back in the early 80s, when Weir (and Coutant) were competitors. All gone now apart from Coutant who are owned by TDK (but still apparently living in the 60s).
awemawson:
A bit more progress today. I've mapped out the logic that drives the four CS lines - one for each RAM chip. It looks as though the board has been designed to be able to be read both in 'Byte Mode' and 'Word Mode' ie 8 bits or 16 bits of data.
In proving the working of the circuit using dead board #1 I was going round in circles as it turns out that the line on edge connector pin A12 wasn't being pulled 'high' by it's 10K resistor. Now that particular lines goes to several pins on both 74HC00D chips , and one of them is driving to 0v when powered up. Impossible to tell which without removing a chip. To this end I've ordered some (minimum order 50 off as they are SOIC-14 smds !)
Board #2 has a faulty "SMD DB" transistor which I believe translates to be a BCW67C - again in an SMD package - so I've ordered some of those (100 off for £1.94 !!)
So this is going to be a learning exercise in SMD reworking for which I've bought a hot air rework station etc - about time I got equipped !
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