OK back onto the Thurlby Thandar SM630 scopemeter which was supposed to have had a backlit display but never worked, and after a chat with bd139 who told me that I should expect to see around 120Vac on the EL panel and then subsequently checking said voltage it was 70Vac. With the total absence of any available service manual for SM630, I dived in to pull the driver out of circuit and investigate.
Using my desoldering gun, the Duratool, lifted the components and checked them, and they checked OK, so I pulled the transformer out and looked for shorted windings and in the process of lifting the tape of the windings, managed to break the winding
. That meant I was resigning myself to having it working just like a SM620, no backlit screen, but
god bd139 came through with a golden nougat and said that small EL drivers could be had from the bay of evil for not a lot of cash
. Great, bd saves the day once again, so off I go and selected 5V USB driver and ordered it, only to have the order cancelled a few days later as the seller could not find it
Found another seller and ordered again. It arrived today, and tonight I set about fitting in the scopemaster, using a couple of connecting posts made from resistor legs, I connected the common ground and supply to these posts and insulated with heat shrink tubing and wired the live feed to the EL panel directly into the PCB and switched ON, it only works, Yah I now have myself a working portable dual trace scope for a fraction of the Fluke 99B that Stewarts of Reading were hoping to sell me for £125, plus delivery and VAT, and it does a lot more besides, and it can be powered via a wall wart or internal batteries.