Repairing A BRC/Thorn Tuner

repairtun

This addresses the problem encountered on Thorn 3000, 3500, 8000 & 8500 series mechanical, single standard tuners. The fault being the plastic washers degrade and crumble thus preventing successful latching.

I take no credit for the method, it was first devised by Mikey405. Below you will see me follow the method to fix the problem which is the plastic parts that lock each tuner button when pushed. I have used this method on at least 5-6 tuners, all with success.

Solution:

All you need are some M6 cup washers for use with 19″ rack equipment and some M6 “penny” washers.

  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 cir-clip 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 cir-clips 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, Re-attach the tuner and tuning bar spring to the mechanism.

tuner1 tuner2

Replacement M6 Cups

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..

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