Repairing A BRC/Thorn Tuner

repairtun

By: Mike Bennett

BRC/Thorn Tuner Repair

The main problem is the plastic parts that lock each tuner button when pushed

Solution:

Regarding those collars, you can use normal washers but, unless you use enormous ones, the springs tend to ride up over the washers and start uncoiling themselves or getting tangled up with the latch mechanism. All you need are some M6 cup washers for use with 19″ rack equipment and some M6 “penny” washers. These can be obtained all over the place, but here’s as good a place as any.

Anyway, below are some instructions on how to fix those pesky Thorn tuners.

To fix the tuner:

  • 1 – Remove the four screws holding the tuner latching mechanics to the tuner itself.
  • 2 – Remove the tuning bar spring and separate the two sections. Put the tuner section to one
    side.
  • 3 – Remove the customer knobs and put them to one side.
  • 4 – Release the latching bar by straightening the two tabs and pulling the latch bar forward.
  • 5 – Remove the latching bar and spring and put both to one side.
  • 6 – Undo the four Phillips screws INSIDE the square-section push-bars. These can be very tight so the correct size screwdriver and a pair of pliers can be useful. Put the screws to one side.
  • 7 – Turn the spindles in a clockwise direction (as viewed from the customer-end) and remove the square-section bars.
  • 8 – Remove the four rear-most circlips (nearest the customer) that stop the spindles from returning too far and put them to one side.
  • 9 – Now the spindles can be slid back enough towards the customer end to remove the spring.
  • 10 – Remove the remains of the plastic collars from the square-section bars and throw them away.
  • 11 – Remove the springs.Slide on to the spindle the metal M6 “penny” washers so that they touch the circlip at the end of the spindle thread.
  • 12 – Take the springs and push each one into the cups of the plastic M6 “cup” washers and then push both back onto the spindle so the back of the “cup” washer touches the “penny” washer.
  • 13 – Slide the square-section bars (slotted end towards the spindle) through the square holes and onto the spindles taking care to make sure the spring doesn’t get trapped or tangled.
  • 14 – Screw the spindles anti-clockwise (as viewed from the customer side) a dozen-or-so turns to join the square-section bars to the spindles.
  • 15 – Replace the rear-most circlips onto the spindles taking care to make sure the rubber and thin plastic washers are on the customer-side.
  • 16 – Screw the four Phillips screws back into the end of the square-section bars. Make sure they’re reasonably tight.
  • 17 – Check the action of the spindles and springs – make sure the square-section bars don’t come out of the slots when the spindles are turned fully anti-clockwise. The bars should be flush with the “chassis” – If they can be turned too far back then an extra “penny” washer is
    needed.
  • 18 – Replace the latching bar by pushing it through the slots and bending the tabs very slightly and re-attaching the spring.
  • 19 – Check the action of the latching bar on each spindle.
  • 20 – Replace the customer tuning knobs.21 – Re-attach the tuner and tuning bar spring to the mechanism.
  • 22 – Test the action of the unit as a whole.
  • 23 – And that’s it. You’re done.

tuner1 tuner2 tuner3 tuner4

3 thoughts on “Repairing A BRC/Thorn Tuner

  1. Wow thanks for the tip I shall be able to fix my 1972 Ultra 12″ black and white set. Its stuck on one channel at the moment others gone are very loose, will get back to you how I got on. Thanks

  2. would I be right in suggesting the old red and white servisol contact cleaner is responsible in part for the breaking up of the plastic mounts in many – particularly thorn sets – the collars look like they have been zapped too !

  3. Hi Stu,

    Not entirely sure that is the case, let me explain why.

    An engineer contacted me when I was in the process of repairing a tuner, he stated that he had some NOS collars in stock and that he would fish them out for me. I thought excellent and what a result, however a few days later he contacted me again which shattered that euphoria. He stated upon finding and opening the NOS packets, the collars had suffered the same disintegration. It would seem the plastic material used after 30+ years just degrades..

Leave a Reply

dialog-information.png
Important Notice: To leave a comment use the box below. You must tick "I'm not a robot" and then complete the puzzle, otherwise the automated comment system will reject your post and treat it as spam.
 

Your email address will not be published. Required fields are marked *

*