UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - AVO CT160

Craig Sawyers · 26th Feb 2018, 2:28 pm

It comes apart - just remove the slotted circular nuts (IIRC) and it just comes apart.

I was lucky when I repaired mine that I chanced on an AVO MK IV testmeter free. This has physically the same meter, with a different scale and different sensitivity. Once you have them open you can swap the scales over, and then screw it together. You can then use an op-amp circuit so that the CT160 innards think they are looking into a real meter, and the opamp drives the replacement meter with the correct current.

The alternative is to buy a 100uA movement with about the same needle length from Farnell (I think I used Anders for another valve tester). You basically take the movement out, then cut the case down so that it fits in the original AVO meter movement recess, and fix everything in place with hot melt glue. Then do that op-amp trick.

26th Feb 2018, 2:28 pm	#10
Craig Sawyers Dekatron Join Date: Nov 2010 Location: Oxford, UK. Posts: 4,982	Re: AVO CT160 - relay activates at power on It comes apart - just remove the slotted circular nuts (IIRC) and it just comes apart. I was lucky when I repaired mine that I chanced on an AVO MK IV testmeter free. This has physically the same meter, with a different scale and different sensitivity. Once you have them open you can swap the scales over, and then screw it together. You can then use an op-amp circuit so that the CT160 innards think they are looking into a real meter, and the opamp drives the replacement meter with the correct current. The alternative is to buy a 100uA movement with about the same needle length from Farnell (I think I used Anders for another valve tester). You basically take the movement out, then cut the case down so that it fits in the original AVO meter movement recess, and fix everything in place with hot melt glue. Then do that op-amp trick.