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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 19th Mar 2019, 11:19 pm   #1
BillDWVA
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Default Ferrograph Series 7 Potentiometer disassembly

Hi,
I have been taking my Series 7 to pieces in an attempt to clean the tracks on a couple of the level pots. but am not sure how to get them apart. I’ve levered up the casing tabs but not sure if the little snap ring locating the outside sleeve (arrowed in pic) has to be removed to get the casing apart? I don’t see an easy way of getting it off and am concerned not to wreck the thing. Has anyone been down a similar path?

The pots are 250k Log and are undoubtedly difficult to source new.

Bill
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Old 20th Mar 2019, 12:20 am   #2
Restoration73
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Default Re: Ferrograph Series 7 Potentiometer disassembly

I would not even consider dismantling it in situ. It is of the moulded carbon type with
graphite brush which have a great longevity. There is no need to remove the circlip
as the brass bush is not captive so that once the tabs are straight the whole outer
concentric pot should be free of the inner. Only a tiny gap is enough to use an
aerosol lubricant but noise can be caused by a leaky cap associated with the wiper, so check these before condemning the pot.
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Old 20th Mar 2019, 1:43 pm   #3
BillDWVA
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Default Re: Ferrograph Series 7 Potentiometer disassembly

Thank you. Got it apart with a bit more gentle prying. I found NorfolkDave’s thread where he did the same strip-down, which was useful.

Bill
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Old 21st Mar 2019, 4:45 pm   #4
Uncle Bulgaria
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Default Re: Ferrograph Series 7 Potentiometer disassembly

That looks very similar to the 'Morganite' gain control in my Ferrograph.

The potentiometer was very stiff so I took it apart and gave it some lubrication and cleaning. The top plate came straight up once the tabs were up, but unfortunately I managed to snap them from work hardening when it went back together. Luckily, the friction from the remainders of the tabs, and being hard up against the panel keeps it secure.

I had to file down the remains of where the panel locator pin was on one of the tone controls as it had snapped off, and make a new one from some glued-on brass as well... I felt the new ones available were all rather small by comparison!
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