Useful cheap small tester...

[pwdrive]

Good man, keep it up.

Lawrence.

[Yorkie]

I bought the earlier version which I boxed up and wrote about in this thread early on and it's given good service since. However, with the newer on costing only a tenner, I succumbed to temptation and bought one for use in the house. Pity they put a ZIF socket on it, so as others have done, I set about removing it. Always a bit of a gamble with plated through hole PCBs. Managed to free up most of the pins, then to remove a few stubborn ones I dismantled the socket, gripped each remaining pin with forceps, then melted the solder on the underside of the PCB.

Unwisely as it transpired, to connect the three take-off wires I decided to fit veropins to three adjacent holes, which on reflection made no sense as each of the three numbered test points have several of the PCB pads to connect to. End result was that I got strange readings so if I put a resistor across say pins 1&2, the readout would indicate the resistance between those pins, that also would show a resistance of several meg Ohms between say 2&3. (See the first pic). That suggested some conductivity between the pins even though I examined them closely with a pocket microscope and nothing showed up. I then abandoned those pins and tried soldering take off leads to the three test pads for SMDs, to no avail.

I'd resigned myself to having jiggered it up and was about to send for another when I decided to cut off the Veropins close to the PCB and carefully grind them down flush with the PCB pads using a small diamond disc in a Dremel type drill. I then connected three take-off wires to pads which are spaced apart and it now seems to work OK. I've attached a few pics, showing both the earlier one I made and the new one. As can be seen, a 1.5 mH RF choke gives the same reading (1.6mH) on both meters.

As is my habit, I've made a little comb-jointed box for this one, this time from a scrap piece of mahogany. The front panel is from a scrap of fibreglass PCB sheet with the copper etched off.

I've also attached a drawing showing the size of the cut-out and the spacing of the mounting holes that might be useful for anyone thinking of boxing up one of these handy little gizmos. I cut a trial panel out out in stiff card to check that everything lined up. I fitted some spacers behind the mounting screws so that the display was flush with the opening.

As an aside, the lead-free solder is high temperature and seems to go even higher when 60/40 is used to make connections.

Just waiting for some of these test clips to arrive on a slow boat from China:

http://www.ebay.co.uk/itm/221627432956?_...2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

[Radio Fixer]

Glad it worked out David. As you said not a fortune lost if you hadn't been able to repair it.

Looks your usual neat production now.

I will, sometime have to find a small coil and measure its L and R on my tester and post it to you to see what you make it (could send a cap as well). It would be something chuck away so there would be no need to send it back.

Those clips are very handy, might bet some of those.

Gary

[AlanBeckett]

Doomed
I ordered a new Box to match my existing one and some M2.5 Screws and Nuts for the holes.
I then did a Drawing - it's a bit tight due to the offset of the Display but a bit of jiggery-pokery fixed it. I considered turning it round to 'Landscape' but decided against.
I made my usual Pig's Ear of cutting out the hole and drilling but I figured it would do.
I mounted the Display with four CS Screws and Nuts.
Then I mounted the Main PCB and I've lost the bottom Row of the Top Line of the Display. I can't see anything wrong so I guess I've managed to bugger something.
I'm inclined to quit at this stage as I don't know which PCB has the problem. However, if anyone has a spare Display kicking about that would be the easy thing to try.

Gloom and despondency reigns.

Alan

[pwdrive]

Cheer up boss, my perfect pipe line turned out not to be so when visiting this morning (water everywhere) a fix was found after a cup o' tea.

Good luck.

Lawrence.

[AlanBeckett]

I've tried Tea, now I'm considering Beer

Alan

[pwdrive]

Good man.

Lawrence.

[AlanBeckett]

The gloom doesn't last long so I decided I'd better find out if it works. I does indeed, apart from the Display problem, but....
I dried an OA91/CV7130 and it doesn't recognise it. However, neither does the 'New' one.
Has anyone else tried it?

Alan

[Nick]

Does it do any germanium junctions? Vf is so much lower than that of Si, maybe it just doesn't recognise them?

[AlanBeckett]

I haven't tried any others yet but that's what I suspected. The same may be true for Schottky Diodes.

Alan