Hameg HM512 scope CRT earth wire

[tallnutt]

Good day to you all,

I have just bought my first scope, a 1972 Hameg HM512, dual channel, 20 MHz, for audio work. Despite its age, I'm very happy with it. Everything seems to work well, except perhaps the V/Div DC calibration seems to go out when it is turned off. I followed the DC adjust procedure in the manual, but every time it's turned on the V/Div fine adjust will cause a y-shift. This was asked by another user here for a similar scope but there was no conclusion posted. However it is not a major problem for me as I do not normally need to use the fine adjust.

My main question is, when I opened it to clean the switches and pots (it actually looked very clean inside already), I noticed a yellow wire hanging loose - connected to the top of the case with a connector that looks like it should be on the back CRT terminals - see picture. This wire is not marked on the manual diagrams and the manual is in German so I'm not sure if it mentions it.

Does anyone know if this wire should be connected and if so, where? Either way, I do not think it should have been hanging lose like that - I could just tape it up and leave it since it seems to be working OK, although it could be a safety issue?

Thanks for any help,

Theo

[shakalnokturn]

Any chances it should attatch to the rear cover - the one that you removed?
Can you spot a small spade tab anywhere on it?

[tallnutt]

Any chances it should attatch to the rear cover - the one that you removed?
Can you spot a small spade tab anywhere on it?

Hmmm.. good idea, maybe it did. I'll check.

[tallnutt]

Any chances it should attatch to the rear cover - the one that you removed?
Can you spot a small spade tab anywhere on it?

Hmmm.. good idea, maybe it did. I'll check.

Found it! It clips onto a ground pin on the top right of the rear circuit board.

Thanks.