Avometer model 8 mk4 - UK Vintage Radio Repair and Restoration Discussion Forum

Mac110274 · 1st Apr 2021, 6:20 pm

Hi all new to the forum thanks for having me my first question is I've got an avo model 8 mk4 got it cheap as the cut put wouldn't stay in when I opened it up I found the latch mechanism wasnt working I've had a read and it turns out there should have been a ball bearing there which luckily I found on the magnet however after sorting that out it appears the length of wire that comes off the back off the pointer is also missing is it possible to repair this if so how long does it need to be and what diameter is the wire can it be
Soldered or would I have to glue it cheers for any advice

pmmunro · 3rd Apr 2021, 12:01 pm

Welcome to the Forum.

If you check cut-out bell crank you should find that it is a die-casting in the Model 8 Mk IV. The push rod will fit in a brass insert which is drilled to receive it. The hole size will give you the correct diameter and it is a simple plain length of piano wire, unlike in earlier meters whose push-rodes are formed into an eyelet. I don't have a Mk IV meter apart at the moment so I can't tell you the correct length.

There is a brass guide bracket for the top end and this bracket has two holes for some reason. However, it will be fairly obvious which one gives the correct alignment.

It may be worth checking that the missing push-rod is not still inside the casing or stuck to the magnet.

Once you have the assembly complete, you will have to adjust the cut-out for the correct sensitivity.

PMM

Mac110274 · 5th Apr 2021, 10:10 pm

Thanks for the info will give it a go however the cut out mechanism is held in with a brass screw and I've found that the threads in the plastic are worn out I'm thinking I will need to get the boards and movement out to repair it somehow.

1st Apr 2021, 6:20 pm	#1
Mac110274 Diode Join Date: Mar 2021 Location: Preston, Lancashire, UK. Posts: 3	Avometer model 8 mk4 Hi all new to the forum thanks for having me my first question is I've got an avo model 8 mk4 got it cheap as the cut put wouldn't stay in when I opened it up I found the latch mechanism wasnt working I've had a read and it turns out there should have been a ball bearing there which luckily I found on the magnet however after sorting that out it appears the length of wire that comes off the back off the pointer is also missing is it possible to repair this if so how long does it need to be and what diameter is the wire can it be Soldered or would I have to glue it cheers for any advice

3rd Apr 2021, 12:01 pm	#2
pmmunro Octode Join Date: Jul 2004 Location: Dundee, UK. Posts: 1,813	Re: Avometer model 8 mk4 Welcome to the Forum. If you check cut-out bell crank you should find that it is a die-casting in the Model 8 Mk IV. The push rod will fit in a brass insert which is drilled to receive it. The hole size will give you the correct diameter and it is a simple plain length of piano wire, unlike in earlier meters whose push-rodes are formed into an eyelet. I don't have a Mk IV meter apart at the moment so I can't tell you the correct length. There is a brass guide bracket for the top end and this bracket has two holes for some reason. However, it will be fairly obvious which one gives the correct alignment. It may be worth checking that the missing push-rod is not still inside the casing or stuck to the magnet. Once you have the assembly complete, you will have to adjust the cut-out for the correct sensitivity. PMM

5th Apr 2021, 10:10 pm	#3
Mac110274 Diode Join Date: Mar 2021 Location: Preston, Lancashire, UK. Posts: 3	Re: Avometer model 8 mk4 Thanks for the info will give it a go however the cut out mechanism is held in with a brass screw and I've found that the threads in the plastic are worn out I'm thinking I will need to get the boards and movement out to repair it somehow.