06-05-2013, 12:03 PM
I have liberated some parts from the chassis that Colbolt Blue kindly donated and got all the ranges working. There is a little bit of drift on the zero control and I will have to check and make sure that I am allowing enough warm up time before I worry about that.
I got out my special dummy load resistor to give me a little bit more functionality with the bench PSU as this has switched currant limit.
I have started checking that the calibration is good enough for me to start on the cabinet.
The flickering lamps proved to be loading with the power set low in the Variac. The pot was OK.
Now for the cabinet.
The spare cabinet is quite a bit different to the original so the original will be sorted out.
The first job will be to take all the fittings off and do then on the bench after the paint has been sorted out. I have some durable mat grey that has been used on heating radiators that get all sorts chucked on them for drying and it has stood up to this very well. It is not quite like the old paint but is good and almost certainly more durable.
While the paint is drying some testing needs to be done on the polyurethane varnish/Tippex mix I intend to use on the lettering.
It looks like the Bakolite repair is still going to go ahead as the donor set is missing a few parts I would like to keep paired with the rest of the chassis. the donor probe box does not fit my cabinet. Also the chassis is more sturdy on my original.
The transformer looks like it was used in a special that did not need a voltage selector to run on 180V to 250V and is working fine once I had sorted the confusion out.
There is one more cap to check before the front goes on again and then it is time to do a calibration.
I intend to make a wall bracket so that the built in stand can clip onto it. This means that it will always be ready for service at the flick of a switch.
Sanding and painting with mat grey got it up very well. Then there is the Bakolite parts. These came up well with car wheel cleaner. The wording came up very well with my home made Tippex/varnish mixture and a wipe over with T-cut got it all looking good again.
The Bakolite repair is now holding things up a bit as the first pack of repair putty did not stick at all to the broken edges of the Bakolite. I will have to either use wires to re-enforce it or try a different type of putty.
First had I bought a card of those blue sausage rolls of epoxy putty. It did not stick to Bakelite at all.
All was not lost though. I made a mold with it.
I got some two part slow epoxy and it was quite runny but with my mold it worked well for the first hinge pin hole. I even found a bit of wire the correct size to keep the hinge pin hole open.
I will have to leave it for a further 24 hours to set fully before I clean the mold flash off and fit the door back on.
The donor chassis did give me the amps shunt and better precision resistors for a few other places where the originals were open circuit.
I will start a new thread in the tips section for the Bakelite repair once I have fitted the door and tested it.
