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Re: Test Equipment Anonymous (TEA) : Discussion and Group Therapy Thread

Posted: Wed Mar 18, 2026 1:15 pm
by Robert
Zenith wrote: Wed Mar 18, 2026 12:42 pm
25 CPS wrote: Wed Mar 18, 2026 1:00 am The other 3400A for sale has a seriously flaking delaminating scale. It honestly looks like water got in it and made the whole thing run. It's still listed for sale too.
The lacquer layer starts to flake. I think storage in even a slightly damp place will cause it, rather than just age. There are a couple of ways of dealing with it. I removed the pealing lacquer very carefully, then replaced the lacquer with the stuff in a can used to fix charcoal drawings. You have to make paper masks so as not to spray the scale mirror. The scale markings under the lacquer are about as permanent as dirt and you have to be careful with them. It has to be done with the scale removed so the spray doesn't get into the movement. You also don't want lacquer flakes getting into the movement. Something of a mission.

Another way would be to make a new scale with a computer, (scan it, or use meter scale software, or maybe scan a good scale), print it making sure it's the correct size, and then go through the fiddly business of gluing it in place.

I'd be tempted by the tatty 3400A - for the right price - which wouldn't be much. The spare parts including screws and feet can be useful, not to mention more valuable parts. Wait two or three weeks, then phone and if they still have it, offer him no more than $10.
These meters should not have a lacquer on the scale. The scales were water transfers that were custom made for each movement in an automated process. One restoration method is to use a dilute waterbased adhesive (Pritt stick dissoved in wate was mentioned but dilute PVA should work). It is applied withe a fine vbrush to the underside of the flake(s) and actually draws the transfer back down onto the surface.

Robert.

Re: Test Equipment Anonymous (TEA) : Discussion and Group Therapy Thread

Posted: Wed Mar 18, 2026 3:26 pm
by Zenith
Thanks for that. It explains a lot, including why the scales are sensitive to damp. I haven't thought about water transfers since I used them as a kid on Airfix kits.

Unfortunately, in some cases the dilute glue and brush method won't work, because the surface layer has lifted and disintegrated.