ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
I have a 700 with no MW & LW . FM is ok. Switch appears to be faulty/dirty with oxidation. I have removed the switch block and was thinking of immersing it in a switch cleaning solution. Has anyone had the same issue and if so how would you clean the switches?
Mike
I would'nt expect the switch unit to stop the am section working,they usually just become noisy due to oxidised contacts,as you say.
Be careful what you use to clean the switches!
As you have the switch bank out of the unit,you can get a good look at it,and actually measure the contact resistance.
I've had some success with cleaning switches in an ultrasonic bath,using the special fluid.
IPA(no,not pale ale,but that might help your mood!) in aerosol form is useful too,as it cleans away the oxide,then evaporates,whereas,most contact cleaners leave a gooey residue which attracts dust.
In some stubborn cases of noisy switches,I've even dismantled them and cleaned the contacts with metal polish,mad or what?(very effective though!)
Super radio's well worth restoring.
Nick
Thank you Nick. If I touched the switch exterior with minimum pressure the AM section started to work
so I took the switch out to clean it. I use a fibre glass stick to clean the contacts I can get to and aerosol cleaning fluid (fast evaporation) to do the bits I can’t get to. Do yo know how I can improve the knurled wheels grip on the tuner mechanism. It seems to grip (not very well) on a piece of fine plastic slid into a groove that runs the length of the plastic. I have removed it and put it back. I wonder if it has gone a bit flat due to use so the wheels don’t grip it.
The inset strip should be a bit "squidgy"(maleable?)as this is what gives the fine tune via the wheels it's action.
You could try cleaning it with the alcohol or may even be able to replace it with a cut down length of thin sealing strip?