Ferrograph 4A: Restoration advice needed
 

Ahoy,

I've recently got the above from Freecycle and am trying to get it going. There's rust and a very tatty case, and as it's to go in my hi-fi setup I'd like to get it pretty nice and polished without entirely removing its character.

I have removed all the chassis and run them through the dishwasher which has brought them up a treat. I am about to start on the component checking, and replacing the Bulgin plug with the Bulgin-made IEC that fits the same holes (PX0579).

I have a few samples of material on the way to see if they will be suitable to recover the case. That '50s olive green is not my bag... I've powder-coated my Lenco turntable RAL Signal Yellow! I digress.

While I am relatively experienced in the practical side of things (valve safety, soldering, manual dexterity) and have a basic understanding of valve circuits, I have near zero experience of how to treat tape decks.

The top plate of the 4A is pretty good, apart from some rusty screws and general grime.

Questions (see pictures):

1 - What do you all think the best approach is to getting the top plate and controls cleaned up? Should I a) go wild: remove everything from below, replace the screws, clean the plate, disassemble and lubricate the motors and get everything shiny. b) remove a screw at a time to identify & replace, in order to avoid having to relocate everything on the top plate, but make it harder to clean?

2 - What to do about the grimy tape transport area? Should this be removed to clean or is it toothbrush and isopropanol? What should I be careful of touching/not touching in this area?

3 - The felt pads look shot. What should I do about it?

Thank you for any advice. I have got the Manual and a tape head cover from Ferrograph World already...

Re: Ferrograph 4A: Restoration advice needed
 

There is a set of pads on e-bay for £4.99 plus postage


Dave L

Re: Ferrograph 4A: Restoration advice needed
 

Thank you Dave - I don't know how I missed those last night when now they are the only result in a search for 'Ferrograph felt'!

Re: Ferrograph 4A: Restoration advice needed
 

Hi,

I have been working on the restoration of Vortexion tape recorders with the same deck and can offer the following:

The deck components are all nickel or cadmium plated and if you strip it completely apart you may be able to either polish the parts or have them pickled and re-plated.

The mounting screws - which are BA thread - are nickel plated and will easily polish up nicely. I did one deck one screw at a time with metal polish with reasonable results.

The paint finish was of a good standard from the factory and so long as there is no actual rust or bubbling from below you can use ‘T -cut’ or similar cutting compound to polish away the dirt and then car wax to bring back the gleam.

Pressure pads can be re-faced with felt. Search for ‘Piano tuner’s felt’ for suitable felt. I cut new cubes of felt and glued them to the existing backing wings after scraping away the remains of the old.

Your deck is a Series 4 and it is a fairly easy job to strip down, clean and re-grease the capstan spindle bearings. Unscrew and remove the top bracket before attempting to undo the nut holding the spindle from below the lower flywheel bearing. Ferrograph used thread lock on virtually every nut and screw.

Hope this helps.
Bill

Re: Ferrograph 4A: Restoration advice needed
 

Thank you, Bill.

Did you polish rusty screws? I will try with one, but fear if you've confirmed they're BA then it may be easier to get some stainless new ones. If it's the bit one sees it's harder to excuse pitted parts than when it's inside the bowels!

As can be seen from the pictures, the paint itself looks good (apart from the rather of-its-time, mould-like greyish green colour) so will wash off quite nicely I think. Without removing the components it will be a little more tricky as I can't just sluice it off.

Thank you for the tips on the bearings. What's your opinion of the tape-head assembly? Does that come under the heading of 'stripping and polishing', or does it need to be treated with care separately?

Edit: I didn't see the pictures before - that felt is a good shout! I have already bought the previous eBay object though, so I'll compare when they arrive. It can always go in the 'spares' box...

Re: Ferrograph 4A: Restoration advice needed
 

When you have got the mechanical aspects sorted out to your satisfaction then don't forget that the paper capacitors in the tape recorder almost certainly need replacing as they will be electrically leaky. Check especially those that are connected to the record/replay head as (if my memory serves me correctly) they can result in DC passing through the head. And this will slowly erase any of your recordings when you replay them. I would suggest you search for a circuit diagram of the 4A on the web to check.

Re: Ferrograph 4A: Restoration advice needed
 

Thank you for the tip, Steve. I have the manual here, with a circuit diagram. I've attached it for future reference. The only one marked as 'metalised paper tubular' in the parts list is C19, which from my amateurish reading of the circuit appears to be something to do with setting the recording level. I'm confused as to what V5 does, as it seems to be after the output. Is C19 a bypass capacitor for the output from the second triode in the ECC83 envelope? Is the ECC83 providing the constant current (I think from the manual it is 1mA) that is the recording meter 'zero' point?

The other capacitors are marked as 'metal tubular', and one of these in the PSU (0.1mfd Metalmite Visconol-X) has measured badly.

Re: Ferrograph 4A: Restoration advice needed
 

V5 is the rectifier / amplifier for the peak reading meter.

Re: Ferrograph 4A: Restoration advice needed
 

Hi,
You have identified the capacitor most likely to cause trouble; namely C19, which couples the anode of V3 (pre-amplifier stage) to the control grid of the output pentode via what looks like R22 (sorry the image is a bit blurred). Another one to check, and possibly replace on sight, is C20 the coupling capacitor from V2, in the previous stage. Modern axial polyester capacitors are OK as replacements and are not expensive.

These capacitors have a high DC voltage stress across them and if they become leaky affect the biasing of the following valve. At best causing distortion and at worse, damaging the associated valve.

Going back to a previous post regarding the screws holding the components to the deck plate; these are plated, domed, countersunk cross-headed and may be difficult to source replacements for. I have only been able to find plain steel screws in BA sizes when looking for new. If you need spares then Terry Martini-Yates at Ferrograph World is your best source of parts for these decks.

Hope this helps?
Bill

Re: Ferrograph 4A: Restoration advice needed
 

Thanks Bill and Barry.

I'm sorry - I didn't realise the diagram had been so reduced as to be almost unreadable! Here is a Dropbox link to download the full-size diagram which is rather easier to interpret.

Bill - could I prevail on you to check the numbers of the components again when the image isn't so illegible? I can't see how C19 couples from V3, as my reading of the circuit has it only seeing signal voltage between the anode of one half of V5 and ground, with R22 just elevating the grid of the second half. Were you perhaps meaning C15, or have I got confused with the way the circuit's drawn? I can't see where the HT source would be for V5, unless there's something high from the anode of the oscillator via pin 4 of plug 5.

C20 is what I would recognise as a coupling capacitor, which is a 350V 0.05uF 'metal tubular' in the manual. This is another 'Metalmite Visconol-X'. I can't find what they're actually made of and thus whether they're likely to have dried out.

I have a stock of polyester/polypropylene 630V capacitors which I was thinking of using, so it's good to know that they're recommended by the cognoscenti!

Screws: I've found the majority come up nicely with a brass brush, apart from one from the tape-counter which has a stripped head. Coming across the same difficulty of finding such a thing, I propose replacing it with a new M3 (available in raised countersunk Philips) which from my tests is easily re-tapped to 6BA without much fuss.

I've already tapped up Mr Martini-Yates for a head cover and the manual - what a help!

Re: Ferrograph 4A: Restoration advice needed
 

^^ Yes, apologies, with a clearer circuit image the components I was referring to are actually C15 and R23 which are in the signal path to the output valve V4.

V5 is the meter drive and it’s HT supply comes via pin 4 plug 5. It looks like it may only be energised when the set is switched to ‘Record’.

Re: Ferrograph 4A: Restoration advice needed
 

V5(b) anode path to HT in record:

V5(b) anode>
P5/4>
SK5/4>
P4/6>
SK4/6>
P1/7>
SK1/7>
P5/5>
SK5/5>
HT.
8-o

Lawrence.

Re: Ferrograph 4A: Restoration advice needed
 

Thanks for the replies. I hadn't been notified of them, I'm afraid! I'll look into the electrics momentarily and trace that path.

The 4A is still having its grotty cabinet material removed, but the chassis are cleaned and I have replaced the old Bulgin with a new IEC Bulgin that screws to the same holes.

I'm still wary of attacking the tape head assembly to clean it. There looks to be some general gunk and possibly corrosion, at least on the plate they attach to.

Can I do any harm with a cloth and isopropanol for an initial go? Anything I shouldn't touch?

Re: Ferrograph 4A: Restoration advice needed
 

I've decided to take the whole head assembly off as it's so gunky. That's meant I'm now cleaning up the great flywheel, I've removed half of one of the motors and all the ancillaries from the tape head.

On another note, does anyone know how to get into the tape counter? I don't want to force anything but need to take the front glass out for cleaning...

Re: Ferrograph 4A: Restoration advice needed
 

It seems not!

I've removed the heads, and wondered if anyone could tell me what their condition is. I don't know what I'm looking for. They're certainly stupendously gunky, though I have brushed off the worst.

Re: Ferrograph 4A: Restoration advice needed
 

In short, the record/play head needs a relap.

http://www.igoramp.it/wp-content/upl...MAGNETICHE.pdf

Re: Ferrograph 4A: Restoration advice needed
 

Thank you, TIMTAPE. That PDF is very helpful, and the process appears understandable.

As far as this head goes, is the brass tripod screwed over the coils, with the hole to attach the head cover, part of the re-lapping process or do I remove it? I imagine the procedure is to sand down the whole of that front brass curved surface, but it's as well to check!

Does the square (erase?) head need the same treatment, and if so does it need removing from its alloy case?

Re: Ferrograph 4A: Restoration advice needed
 

It's great isn't it. Lots of practical information there.

Yes the entire face is lapped. Obviously the base would need to be temporarily removed. Just be careful with lapping, especially if it's the first time for you. A little bit at a time, with frequent visual inspection with a magnifier in a strong light. There's only so much metal there before the fine head gap opens out and then it's a bin job. Ideally practice your technique on something that's OK to destroy!

I wouldn't attempt relapping the erase head. It has a ferrite core rather than permalloy and I believe special techniques were used to relap them.

Re: Ferrograph 4A: Restoration advice needed
 

I love that open head design!

Re: Ferrograph 4A: Restoration advice needed
 

Yes, unusual compared to later heads which are usually potted in some sort of epoxy, making internal repair virtually out of the question.