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UK Vintage Radio Repair and Restoration Discussion Forum (https://www.vintage-radio.net/forum/index.php)
-   Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players (https://www.vintage-radio.net/forum/forumdisplay.php?f=35)
-   -   Ferrograph 4A: Restoration advice needed (https://www.vintage-radio.net/forum/showthread.php?t=151194)

Ted Kendall 5th May 2019 8:14 pm

Re: Ferrograph 4A: Restoration advice needed
 
Quote:

Originally Posted by Uncle Bulgaria (Post 1142927)
On mine the screws are not tensioned...adding washers as shims seems the only option. From the quality of the rest of the machine, this lack of precision seems unlikely!

Apologies - touch of brain fade. I'd say shimming is the way to go. The Ferro has never struck me as a particularly precision device, more a design centred on dependability, which given its origin as Admiralty-specified equipment, would make sense. That, and the fact that it was conceived when the sub-studio state of the art otherwise was the Brush Soundmirror...

BillDWVA 5th May 2019 8:23 pm

Re: Ferrograph 4A: Restoration advice needed
 
Quote:

Originally Posted by Uncle Bulgaria (Post 1142927)
On mine the screws are not tensioned, except by the weight of the motors hanging off them when the machine is lying down. The screws each thread into hex standoffs that butt up against the top plate, and have their other end connected to the long hex screws that hold the rotor bearings and motor assembly together.

The standoffs are all the same length, so adding washers as shims seems the only option. From the quality of the rest of the machine, this lack of precision seems unlikely!

You are correct; the motors are adjusted so that their spindles are square to the top plate by adding or removing washers under the hex standoffs. From my experience of replacing the take-up motor on a Series 4 it is a bit of a faff to slip extra washers in and I resorted to coating them with grease to ‘stick’ them into place whilst I got the screw back in.
Note that you can adjust the reel adaptor height by undoing the tiny socket head locking screw in the hub. 1/16” Allen key needed.

Bill

Uncle Bulgaria 21st Oct 2019 3:45 pm

Re: Ferrograph 4A: Restoration advice needed
 
After months of travel, I'm back home and ready to deal with the loud hum that's just started. I think it's time to check the filter and reservoir capacitors... Then back to the motors!

TopTip 23rd Nov 2019 1:44 pm

Re: Ferrograph 4A: Restoration advice needed
 
I am about to start restoring my 4A and this thread has been a great read and resource.

However, this is also about the 14th or 15th reel to reel that I am renovating. So I learned any number of tips and tricks along the way.

One I learned too late (into my 10th machine perhaps?) is to install a hidden switch and jack (a mini-DIN works well) to provide a direct output from the playback head. This is frankly what every turntable has / is and the very first tape machines also do.

Here is why. What is the most likely operation on a tape recorder? Record tapes? Not really, not that often. First, there are better recorders and also you record once, playback many times. Then there are pre-recorded tapes.

Now, no matter how well restored, the electro-mechanical construct that the tape recorder is, will occasionally act up. One channel gets lost or has low signal. There may be hum. Bypassing all the internal electronics and using an external preamp is, in such instances, a blessing.

Question is, where do you find a “tape reproduce preamp”? There are only 2-3 on the market and, just like everything low volume / hifi these days, they cost a lot. There are a few old ones on eBay. Alternatively I have modified “moving coil” turntable preamps, to change the RIAA curve to something closer to tape playback. These are plentiful and good ones can be had for way below £100.

Uncle Bulgaria 24th Nov 2019 11:20 pm

Re: Ferrograph 4A: Restoration advice needed
 
Interesting, thanks for your thoughts. I've been using mine the opposite way - it's got a battery-powered MM preamp running from my bedroom turntable, using the Ferrograph's fine amplifier and speaker as output!

Mainly because I've been concentrating on getting the Uher done before sorting out the tape transport problems on the Ferrograph, although the hum has now reared its head!

Boulevardier 25th Nov 2019 12:42 am

Re: Ferrograph 4A: Restoration advice needed
 
TopTip - "Question is, where do you find a “tape reproduce preamp”?"

It's not a big deal to build your own - a few op-amps and a handful of resistors and capacitors. I can vouch for the tape pre-amp in the Stuart tape circuits (Wireless World, 1970s). Very simple and excellent quality - well up to semi-pro standard.

Mike

Uncle Bulgaria 25th Nov 2019 3:34 am

Re: Ferrograph 4A: Restoration advice needed
 
Can you post the circuit?

llama 25th Nov 2019 9:44 am

Re: Ferrograph 4A: Restoration advice needed
 
Post No 11 has it here:

https://www.vintage-radio.net/forum/...d.php?t=159970

Graham

barrymagrec 25th Nov 2019 12:50 pm

Re: Ferrograph 4A: Restoration advice needed
 
Quote:

Originally Posted by Boulevardier (Post 1194278)
TopTip - "Question is, where do you find a “tape reproduce preamp”?"

It's not a big deal to build your own - a few op-amps and a handful of resistors and capacitors. I can vouch for the tape pre-amp in the Stuart tape circuits (Wireless World, 1970s). Very simple and excellent quality - well up to semi-pro standard.

Mike

You would need transformers to match it to the low impedance Ferrograph heads though.

I was always confused by the lack of a hf response trimmer when the circuit first came out.

Boulevardier 25th Nov 2019 8:08 pm

Re: Ferrograph 4A: Restoration advice needed
 
Uncle Bulgaria. Yes, I'll try and look out the Stuart circuits over today or tomorrow. It's true they were specifically designed for Bogen heads anf I don' know how these compare with Ferrograph heads. Stuart did however give some tips for modifying for other heads.

llama 25th Nov 2019 8:37 pm

Re: Ferrograph 4A: Restoration advice needed
 
Just follow the link I posted above.
Graham

Boulevardier 25th Nov 2019 8:44 pm

Re: Ferrograph 4A: Restoration advice needed
 
2 Attachment(s)
Herewith Stuart tape circuits articles, and also the specs of the Bogen heads for which it was designed (as given by HW Hellyer in Tape Recorder magazine). Stuart also gives circuit for a discrete-component version towards end of articles - just three BC108s and some passive components! I think the specified RCA 3048s might be difficult/impossible to source now. But any high quality, low-noise op-amps will do just as well. So simple, it might be worth just breadboarding and trying.

Out of interest, I found out by accident that this circuit also makes a rather good pre-amplifier for a magnetic cartridge...

Mike

[EDIT - sorry Graham, I hadn't seen your post when I posted this.]

TopTip 2nd Dec 2019 12:37 am

Re: Ferrograph 4A: Restoration advice needed
 
Embarrassingly, after all this, I opened the lid of my Ferrograph and was reminded that it is in fact a 2N, not a 4. What I think I will do is install a new stereo head (I have quite a good sekection) and use outside amplifiers, as above. I only need it for playback.

Reason I wanted to modify an existing MC preamp (rather than build from scratch) is because of the one thing four decades of DIY electronics taught me: The hardest part of any project (other than making the PCB) are the enclosure, jacks, switches, labels and the power supply and those are what commercial manufacturers provide to perfection.

llama 2nd Dec 2019 9:43 am

Re: Ferrograph 4A: Restoration advice needed
 
Please let us know how you get on. MC pre-amps are available for about £12 (don't know what that is in $$$) and seem to perform quite well.
Graham

TopTip 3rd Dec 2019 2:30 am

Re: Ferrograph 4A: Restoration advice needed
 
1 Attachment(s)
Looks like the first order of the day for me is to clean up this gooey mess.
Then where do I find new rubber idlers?
I thought whether I should instead try to adopt a belt? The rotation will be correct and it will probably improve speed stability. I will not be able change speeds but I do not really need 3-3/4” as my intention for this deck is to play prerecorded tapes, which are mostly 7-1/2 ips.

flywheel 8th Dec 2019 7:13 pm

Re: Ferrograph 4A: Restoration advice needed
 
I've never seen that on one of the older Ferrograph decks, but it's a common problem with their 70s models due to poor original quality from the supplier of the rubber/neoprene moldings, only making itself known years later. The idlers in their 50s decks (like yours) through to late 60s models are usually still fine, and are often sold on eBay to buyers looking to fix this on the later decks.

In my experience the only thing that shifts this is acetone - and quite a lot of it - but you have to be very careful to keep it away from paintwork and the wiring insulation.

Example of eBay sale of Ferrograph idlers (I have no connection with the seller): https://www.ebay.co.uk/itm/3-x-FERRO...kAAOSwonBZ~yrf

TopTip 9th Dec 2019 6:45 am

Re: Ferrograph 4A: Restoration advice needed
 
1 Attachment(s)
I have a second 2N. I bought it for very little as it is in very rough shape, bent in several places but complete. I thought I could use it for any spares I may need, like motors or just screws, nuts and washers. The idlers on this one have not turned into goop like the other but still unusable, all cracked. Incidentally, alcohol cleans this rubber mess well, if a bit slowly. I will try acetone too, thanks.

Uncle Bulgaria 19th Jan 2020 7:28 pm

Re: Ferrograph 4A: Restoration advice needed
 
I've just replaced the filter/reservoir capacitor with a new Cricklewood dual-can. I'm astonished at the difference. I hadn't realised how on the edge the Dubilier was!

Playing through the second input from the computer; with nothing playing I can turn the gain up full and have no hum or hiss noticeable from a foot away!

Now on to the tape alignment. An 8" reel rubs as it rotates, and there's not enough oomph to rewind unless I take the tape right out of the guides. Better get back to levelling...

Hartley118 19th Jan 2020 9:58 pm

Re: Ferrograph 4A: Restoration advice needed
 
Quote:

Originally Posted by Uncle Bulgaria (Post 1209386)
......


Now on to the tape alignment. An 8" reel rubs as it rotates, and there's not enough oomph to rewind unless I take the tape right out of the guides. Better get back to levelling...

I’ve always found my Ferrographs need a bit of manual assistance when starting to rewind. Memory suggests that Ferrographs have always been that way.

Martin


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