The Craftmans Shop > New from Old
The Sequel - Oh Blimey I bought a CNC Lathe (Beaver TC 20)
modeng200023:
Andrew, you just amaze me :clap:
John
Muzzerboy:
Yes, the hot air ones are the way to go and don't cost a lot. The irons with the funny tips end up ripping pads off if you aren't careful and you never seem to have the right tip anyway....
awemawson:
--- Quote from: modeng200023 on September 05, 2021, 11:03:58 AM ---Andrew, you just amaze me :clap:
John
--- End quote ---
Thanks John :palm:
Some more progress. I've linked out the faulty transistor from Collector to Emitter to allow me to carry on testing. This transistor is involved in the switching to / from battery back up so in this mode I can do without it!
This has let me prove that A12 inhibits all Chip selects when low, and the other four control lines (B13, B14, C13, C14 ) provide Chip Select for each individual Ram chip.
All a bit odd, but workable.
The picture of the link across the SMD transistor emphasise how small SMDs are - that huge hoop of billet is actually the lead from a tiny 1/8 watt resistor :clap:
PekkaNF:
--- Quote from: awemawson on September 04, 2021, 10:59:06 AM ---....
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.
--- End quote ---
I have bought this kit:
https://sensepeek.com/pcbite-kit-with-2x-sp200-200-mhz-handsfree-oscilloscope-probes
pros:
1: It has pretty much standard 10x scope probes and they work per spesification, the business end is small and has a standard needle pogo pin.
2: probes are held down with a weight and the swan neck tube holds them in place, it works
3: The magnetic standoffs works too.
cons:
Ground hook is not that great, but it has standard square pin connector and easily replaced.
I though of making something like that myself and played around of different parts etc. and never got really good results. I tried those cheap colorful flexible coolant hose thingys, but they really are not very precise or dependable in real use.
This commercial product does what I needed better that what I could have cooked. However it is just one part and I still solder wires and connectors on boards, just getting better at it.
There is a 1:1 flying lead probe too for non coaxial cables, but those I haven't tried.
Pekka
awemawson:
That's a very cunning system. The magnetic pillars are on my 'to do' list for making and although that probing system looks pretty good it won't let me probe both sides of a board at once.
I fear I'm stuck tagging on wires with solder at times !
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