Ferrograph 4A restoration

[Craig Sawyers]

I was lucky enough to collect, from another list member (mole42uk, AKA Richard), a FOC Ferrograph 4A a couple of weeks ago. Collected from Bristol, and gaining a long arm hauling it back to the car! I set about getting it up and running, and restored nicely. Fortunately it was in really good shape.

1. Outer Rexine casework cleaned with gentle application of CIF and warm water. Lots of grime and grunge from 50-odd years.

2. Removed the power supply chassis and the main amplifier chassis. Not as easy as it sounds because Ferrograph used locktite on every single fastening.

3. Washed both chassis in the sink. This is not as horrible as it sounds - this was an accepted procedure at Tektronix before any service repair or calibration of an oscilloscope. I took the valves out first of course!

4. While these were drying in the airing cupboard, I checked the valves on my AVO MkIII. All were absolutely perfect.

5. Replaced all the TCC Metalmite Visconol x paper in oil capacitors with polypropylene. They go randomly leaky. Replaced resistors in the EQ parts of the circuit - they were all a long way out.

6. The mains socket was broken. Although most original replacements are silly money, even on eBay, I chanced on a NOS plug and socket pair (on eBay) for a mere £14.

7. Cleaned out the inside of the box - mucky it was.

8. The grey paintwork on the top of the deck was wiped over to get the worst of the muck off, and then polished to a high shine using Duraglit.

9. Under the deck, I oiled the motor bearings top and bottom, oiled the idler wheel bearings, and oiled/greased all the linkages. The only one I have failed with is re-greasing the flywheel bearings - It looks like a lot of disessembly to get the flywheel out.

10. Although the heads had the usual dummy in place for head 3, I managed to get an FR16 half track stereo record/playback head in almost unworn condition from the US via a friend to minimise shipping cost. I need to build a suitable EQ amp for it, but that should not be too horrendous. Idler wheels were cleaned using Isopropyl alcohol was was the flywheel rubber tyre.

11. The meter glass was broken half missing, and the remaining bit was loose and lying on the pointer. Getting the meter out is a real game - you really have to take the six fastenings securing the front panel to the chassis to get to two of the nuts. Anyway once out, the glass measured 1.4mm thick. I cleaned off the black pitch-like stuff that meter glasses were attached, and procured (eBay) a small sheet of 1.5mm thick perspex. That was easily cut to the correct size and shape, and attached using superglue.

12. Reassembly of the meter to chassis was, as they say, a reverse of the disassembly. I took the knobs off for cleaning, and wiped and then duraglitted the front panel.

13. Once all the chassis were back in the case and wired up, the whole thing fired up first time. I'd bought some Ferrograph reels, some of which had tape on them - and to my delight it was a live recording of a chamber orchestra. A good one too. So I got the chance to listen to something - and given the old paper cone Goodman's internal speaker it sounds very nice indeed!

Craig

[SteveCG]

... and you have a working neon on the front panel too ...

I know what you mean about a long arm, especially if you have a so-so back! There is a lot to be said for lightweight gear when you get older, except you don't get the chance to hear a recording made on Ferrotape A.

[mole42uk]

Excellent! I'm glad it went to a good home, much better than hiding under the bench as it has been for the past seven or eight years!
Glad to know it's back in action.

[Craig Sawyers]

I'm pleased with the old girl - particularly since I originate from 7 miles west of Newcastle, so this particular machine was built around 15 miles away when I was about 5 years old.

And as an aside, Richard (among other things) is a musical instrument restorer - as a lapsed amateur clarinetist, I was astonished when he pulled a restored 1815 instrument out of his display cabinet - which has nothing like enough metalwork to get all the notes! Visually more like a recorder with a reed mouthpiece and some rudimentary keywork.

The clarinet was developed very late in musical instrument terms - late 1700's - so Richard's clarinet is exceptionally early. It is the same sort of instrument that Anton Stadler played the original Mozart quintet and concerto on. When Mozart sent him the manuscript for the concerto "Mozart - I can't play this" - "Are there notes that you can't get on your clarinet?" - "No" - "Well, my dear Anton, it is a concerto - you must practice!".

Craig

[llama]

Excellent. I'm almost prompted to do mine.

Does the FR16 need transformers to get into an EQ amp? Are you home-brewing it and, if so, valve or solid-state? And do you have a source for the head plugs (Plessey?)?

Graham

[Phil G4SPZ]

Excellent work! Well done, and what a nice looking machine as an outcome - surely this thread should be under "Success Stories"?

I have two Series 6 Ferrographs but only enough room to display and use one of them. Neither looks as good as yours though! It's good that these old classics get an hearing now and again.

[Craig Sawyers]

Originally Posted by llama

Does the FR16 need transformers to get into an EQ amp? Are you home-brewing it and, if so, valve or solid-state? And do you have a source for the head plugs (Plessey?)

In principle.

But low noise electronics is so easy now that a transformer isn't really needed.

Looking at the spec for the head (28 mH, 11 ohms) and about 12mV output via a 1:5 transformer. That works out as around 2.4mV from the head at 3% distortion.

Something like the SSM2019 with <1uV noise over audio bandwidth. Assuming a dynamic range of 70dB (much higher than the 4A can do) below 2.4mV is about 0.7uV. That works out just fine. Amplifying flat with about 300 times gain using the SSM2019 followed by EQ should be the way to go.

But I'm kind of learning about tape EQ, so now the head is installed (just plugs straight into the octal socket under the dummy) I'll do some measurements and bone up on what record/playback EQ I need to apply.

Of course Ferrograph used inductors in the EQ, so it is going to be a matter of measurement to figure some of this out.

Craig

[Mike Phelan]

Excellent job, Craig.

I must dig my Series 5s out and make one good.

I have always admired the design of the Wearite deck; they didn't copy anyone else but started from scratch, using standard materials in most parts and a very low component count.

[avocollector]

Super job - really envious. Have one of these machines stashed away for a rainy day so now inspired by your example to get on with it.

[Tim]

I really love these machines and used to have two or three. I even mended a few when I used to volunteer at our local hospital radio , and one for a friend who worked in radio, and wanted it for a listening and editing machine, and another(a 422) for an elderly relative. IMHO the series 4 deck was the best.