Replace pinch roller on Sonifex NAB Cartridge machine

Once a common sight in Radio stations around the world, the NAB Cartridge machine or Fidelipac was used for short jingles and announcements, sometimes even for longer recordings. Using a similar sized cartridge to a domestic 8 track machine the NAB cartridge was different in that the pinch roller was not in the cartridge but would hinge up in the player and hold the tape against the capstan. Running at 7.5 inches per second (ips) compared to 3.75 ips in domestic cart machines the recording and reproduction quality good be very good but it was the ease of use and cueing ability offered by these machines that made them so useful in broadcasting.

We have Sonifex cart machines that while very well built do have rubber parts that will degrade over time and reduce the transport performance. Luckily we have some of the last remaining stock of new pinch rollers, motors and capstan drive belts.

The pinch roller in one of our machines had become quite hard and the rubber shiney over time. A pinch roller in this state may not hold the tape as securely and could also have flat spots both leading to increased wow and flutter and poor tape handling. These pinch rollers also have high quality cartridge bearings pressed into their shell. Over time these loose their lubrication, wear, become rough feeling and will also add to poor tape handling.

Older, fragile and valuable tape must be handled and used carefully. A ‘chewed’ tape caused by a poorly maintained tape transport in any tape machine, audio or video is a disaster and hard to recover from perfectly.

Sonifex NAB cart pinch rollers

Both halves of the cart machine case need to be removed to easily change the pinch roller. While the access is good and the machine, in this case a Sonifex microHS, had been designed for easy servicing the pinch roller is still a little fiddly to get to so I removed the transport from the main chassis.

Sonifex NAB cart machine microhs transport removed

To remove the pinch roller a small slightly hidden C clip must be removed you can see in the image above the slot machined into the roller shaft where it sits and holds the roller. This is hard to remove as the plastic bush on top of the roller stops you getting a small screwdriver in. I managed to remove the C clip with some fine circlip pliers. Be careful not to loose the clip if you don’t have spares, they fly away very easily!

Now the new roller can be placed on the shaft. It’s a good idea once all the transport is out to give everything a good clean with IPA.

Sonifex microHS new pinch roller

On this machine, the castan drive belt was quite slack so a new one was fitted, which is easy now the transport is removed. First though the capstan flywheel and motor pulley were cleaned of all the old rubber belt residue that tends to accumulate over time.

Sonifex NAB cart machine capstan flywheel

The last thing to do is check the pinch roller pressure. This is important to as to high or too low will increase wow and flutter, increase wear to the bearings and capstan surface and give poor tape handling. Due to the design of these NAB cart machines, the pinch pressure needs to be checked with a special cartridge. The pinch pressure is then adjusted from a screw pot on the top PCB seen outlined below in green.

NAB cartridge pinch pressure adjustment

That’s it, time to play carts again.

6 comments

Dermot Redmond

That was a very interesting read about the pinch roller replacement ! I wonder if anybody could help me with a problem I am having with my Sonifex machines. I have 3 machines.. One is a Record/Play unit and two are PlayOnly units. The Record/Play unit has a ‘noise reduction switch’ that removes a hissing sound. This hissing sound is quite bad when it’s switched off. But when it’s switched ON, the sound quality is superb ! However, with my two Play Only units, the hissing sound is there all the time, as I cannot find any sort of noise reduction switch (the circuit boards on the Record/Play unit is completely different than that of the Play Only units. It is definitely NOT caused by the heads being out of alignment…. they are in perfect position. When a cart is NOT being played (in the Play Only unit) the hissing noise is there when the slider/fader on the mixing desk is pushed up. So it is clearly something to do with its circuit board ! When the noise reduction switch is turned OFF in the Record/Play unit, the hissing noise is exactly the same as that of the Play Only units. So there simply has to be a noise reduction switch on the circuit board of the Play Only units, but as I said, the circuit boards are completely different. Would anybody know where this noise reduction switch is located on the Play Only unit ? I would be most grateful for any advice ! Thank you for reading this !

Simon Greenwood

I may well need a new pinch roller, but I have not got that far yet. Firstly I am not entirely sure what the model number of my unit is. I am pretty sure it is made by sonifex, at least that is what I believed in 1977. It is branded by Roger Squire as a S3000 MkII. On opening it up the belt was completely perished and came apart in my hand. Anyone have an idea how I can identify the unit and get a new belt?

Hello… I have two concerns and am really hoping you can help me. I have three Sonifex Cart Machines. One is the record/play module and the other two are play only. When I play my carts in either of the play only machines, there is a terrible hissing sound, which is not present in the record/play module. There is a noise reduction switch on the circuit board of the record/play module, but I cannot find one on the play only machine’s. Their circuit boards are much simpler and less packed with parts, but I still cannot find a noise reduction switch. Do you know if they have one as well, and if so, where is it located. My other problem is the belt on the wheel of one machine which keeps flying off. Why should this happen. And if it’s due to old age, do you have any belts available. I would be so very grateful for your advice and assistance. Yours sincerely, Dermot Redmond email redmondjdermot@googlemail.com

Hi,
I have a roger squire S3000 jingle machine, I have no idea what it is used for nor whether it works, does it have any value or should I just bin it?

Regards

Hi Darius

Thanks for your comment – it sounds like you have a NAB broadcast cartridge machine, commonly used in radio stations to play short jingles and announcements. Some of these have a value to owners of cartridges but some are more fragile and difficult to repair than others. I’m not familiar with this model. Can you post a picture or send one to adrian@thegreatbear.net?

Hi from Chris.

Anyone got Manuals for micro C.Q.R Nab recorder and player.Mine has just stoped recording,Plays O/K.

If you know it can have life, put into the old girl,point me in the right direction.

Thanks in advance

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