TRIO 9R-59DS Tuning Mechanism Question - UK Vintage Radio Repair and Restoration Discussion Forum

snowman_al · 22nd Feb 2019, 10:40 am

Wonder if any of the TRIO experts can advise please?
Inspired by some recent posts, I though it about time I gave some TLC to this well worn example.

First problem is the tuning drive shafts 'float' back and forth in use.
This cannot be correct as turning one knob affects the tuning of the other shaft, due to the different tensions of the drive cords.
Worse is that the free play causes the main tuning cord to fray against the mounting bracket.
A previous owner obviously 'fixed' this by cramming the tuning knob hard against the front panel... but that is daft and has resulted in a worn section on the shaft and a damaged front panel.

Does anyone have experience in this part of the set, know how the end float is adjusted or is there just something missing? Help please...

Thanks Alan

Restoration73 · 22nd Feb 2019, 10:59 am

There's no excuse for the panel damage if a thick felt washer had been used.

Normally such a design would have had circlips to prevent movement, with a groove in
the spindle. However you may be able to use a metal insert from a scrap knob which
will have a grub screw to restrict spindle movement. Washers may reduce friction further.

Station X · 22nd Feb 2019, 11:05 am

My own set has a fairly wide gap between the main tuning knob and the front panel with no felt washer. There's vey little end float on either knob.

I don't know how end float is controlled, but if you're desperate I'll take the lid off and have a look.

G6Tanuki · 22nd Feb 2019, 2:00 pm

On mine, the concentric shaft runs in 'top-hat' brass bushes where it goes through the holes in the U-shaped bracket; the whole thing is stopped from moving backwards and forwards by circlip which should sit in a groove on the inner, smaller-diameter shaft at the point I've marked with an arrow, which stops the inner shaft moving through the outer bush; there's then another circlip (or is it a washer?) that stops the outer shaft moving in and out of the rear top-hat.

This second circlip (or washer) is directly against the inner face of the rear 'leg' of the U-bracket.

No felt washers or anything, and no knob rubbing the face-plate. I guess there's a maximum of 1mm of end-float on the outer knob.

The biggest problem with mine is that the oil/grease between the inner and outer spindles has dried out with age so the 2 knobs tend to interact...

snowman_al · 22nd Feb 2019, 5:39 pm

Thanks for the input so far, I feel there is something missing on this one.

I have the tiny circlip you point to, I took it off to clean the shafts. That keeps the two spindles together.

But there is nothing on mine to stop the shafts moving into the set, other than the knob or the dial cord... (You can see on one picture it has been rubbing for some time too. No groove for a front circlip and no sign of a rub mark for a washer/collar.

I first wondered if the rear, non turning, flange on the shafts was glued or pressed into the U frame? Problem then is that the main tuning part of the shaft is not supported at the front of the U frame as the diameter changes just at that point. About 1/2mm at the U which causes 2 or 3mm movement at the end of the shafts. Enough to easily break any bond between the two.
The other issue now is that it has even worn front hole in the U a little so adding to the movement.

I have only found one picture of a Trio with the knobs removed, and that looks as if there is a brass collar in the hole too? But that is the previous version - did they alter it after? Or is there something lost on my one?

Looks like a bit of creative engineering is needed...
Alan

G6Tanuki · 22nd Feb 2019, 6:46 pm

Mine has the brass top-hat bush in the front hole of the U-shaped bracket. The 'step' diameter-change in the large-diameter shaft is what engages with the front top-hat bush and limits its ability to move forwards (the front top-hat bush being installed with the 'flange' on the inside of the U-bracket).

I fear that yours has been 'got at' and has some elements of the tuning-spindle assembly missing.

Humptydumpty · 24th Feb 2019, 10:34 am

Most of these Trios will have this problem after some time . I would fit a block inside the [ u ] bracket to keep the shaft in on place. Or even two split , like one top and one on the bottom of the shaft .

Station X · 24th Feb 2019, 10:42 am

Perhaps a nearby member with a lathe could turn up a bush for the OP. It's a simple enough job, but requires access to the 'U' bracket and shaft to ensure an accurate fit.

g4aaw pete · 24th Feb 2019, 2:00 pm

Hello Alan

had a look in my secret box of bearings & wonder if this item would be anywhere near required as a front bearing?

snowman_al · 24th Feb 2019, 2:41 pm

A quick update to the post.
First I wanted to keep it as original as possible, just in case I find a correct solution in the future.

The outer 'band set' shaft is 11/32'' (8mm). I found an old 1/4'' (6.3mm) shaft support from my spares box so it need to be drilled out. (It was the only one with enough thickness I could find, then only just.)
Then I filed the hexagonal section thin enough to fit between the U bracket and face plate. The steel chassis thickness in fact.)
Next I shortened the threaded section to give just enough space between the band set knob and the front face plus 1/2mm for float. Unfortunately I will still have to use the knob to prevent the shaft sliding back, but that is now settable and I know it will not scuff the face plate.

Only small problem is the nut to fit the support collar is not the correct thread, but will do until I can find the correct one.

Pete, thanks for the offer. If this does not prove satisfactory, I will consider opening up the U bracket and face plate to take a bearing. I could well be back to you.

Alan

This is work in progress

g4aaw pete · 24th Feb 2019, 3:09 pm

Hello Alan

by the looks of things, you've come up with a good fix.
If you decide you'd like my bearing though, PM me your address & I'll post it to you.

By the way, notice you're an ex-xeroid like myself!

snowman_al · 24th Feb 2019, 5:21 pm

Thanks everyone,
Latest is:- I have put it all together, re-strung both dial cords and lined the pulleys and drive shafts up and it works as I would hope.
Smooth enough, does not 'shoot' all over the place as you touch / turn the knobs and no interaction between the two dials.
Just listening to the 40 metre contest as I report.

A couple more oddities on this set to understand, but happy to give it some proper TLC now.

Alan

22nd Feb 2019, 10:40 am	#1
snowman_al Octode Join Date: Dec 2018 Location: Llandeilo, West Wales, UK. Posts: 1,092	TRIO 9R-59DS Tuning Mechanism Question Wonder if any of the TRIO experts can advise please? Inspired by some recent posts, I though it about time I gave some TLC to this well worn example. First problem is the tuning drive shafts 'float' back and forth in use. This cannot be correct as turning one knob affects the tuning of the other shaft, due to the different tensions of the drive cords. Worse is that the free play causes the main tuning cord to fray against the mounting bracket. A previous owner obviously 'fixed' this by cramming the tuning knob hard against the front panel... but that is daft and has resulted in a worn section on the shaft and a damaged front panel. Does anyone have experience in this part of the set, know how the end float is adjusted or is there just something missing? Help please... Thanks Alan Attached Thumbnails __________________ Never Leave Well Enough Alone...

22nd Feb 2019, 10:59 am	#2
Restoration73 Nonode Join Date: Jun 2013 Location: Surbiton, SW London, UK. Posts: 2,801	Re: TRIO 9R-59DS Tuning Mechanism Question There's no excuse for the panel damage if a thick felt washer had been used. Normally such a design would have had circlips to prevent movement, with a groove in the spindle. However you may be able to use a metal insert from a scrap knob which will have a grub screw to restrict spindle movement. Washers may reduce friction further.

22nd Feb 2019, 11:05 am	#3
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: TRIO 9R-59DS Tuning Mechanism Question My own set has a fairly wide gap between the main tuning knob and the front panel with no felt washer. There's vey little end float on either knob. I don't know how end float is controlled, but if you're desperate I'll take the lid off and have a look. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

22nd Feb 2019, 2:00 pm	#4
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,996	Re: TRIO 9R-59DS Tuning Mechanism Question On mine, the concentric shaft runs in 'top-hat' brass bushes where it goes through the holes in the U-shaped bracket; the whole thing is stopped from moving backwards and forwards by circlip which should sit in a groove on the inner, smaller-diameter shaft at the point I've marked with an arrow, which stops the inner shaft moving through the outer bush; there's then another circlip (or is it a washer?) that stops the outer shaft moving in and out of the rear top-hat. This second circlip (or washer) is directly against the inner face of the rear 'leg' of the U-bracket. No felt washers or anything, and no knob rubbing the face-plate. I guess there's a maximum of 1mm of end-float on the outer knob. The biggest problem with mine is that the oil/grease between the inner and outer spindles has dried out with age so the 2 knobs tend to interact... Attached Thumbnails Last edited by G6Tanuki; 22nd Feb 2019 at 2:06 pm.

22nd Feb 2019, 5:39 pm	#5
snowman_al Octode Join Date: Dec 2018 Location: Llandeilo, West Wales, UK. Posts: 1,092	Re: TRIO 9R-59DS Tuning Mechanism Question Thanks for the input so far, I feel there is something missing on this one. I have the tiny circlip you point to, I took it off to clean the shafts. That keeps the two spindles together. But there is nothing on mine to stop the shafts moving into the set, other than the knob or the dial cord... (You can see on one picture it has been rubbing for some time too. No groove for a front circlip and no sign of a rub mark for a washer/collar. I first wondered if the rear, non turning, flange on the shafts was glued or pressed into the U frame? Problem then is that the main tuning part of the shaft is not supported at the front of the U frame as the diameter changes just at that point. About 1/2mm at the U which causes 2 or 3mm movement at the end of the shafts. Enough to easily break any bond between the two. The other issue now is that it has even worn front hole in the U a little so adding to the movement. I have only found one picture of a Trio with the knobs removed, and that looks as if there is a brass collar in the hole too? But that is the previous version - did they alter it after? Or is there something lost on my one? Looks like a bit of creative engineering is needed... Alan Attached Thumbnails __________________ Never Leave Well Enough Alone...

22nd Feb 2019, 6:46 pm	#6
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,996	Re: TRIO 9R-59DS Tuning Mechanism Question Mine has the brass top-hat bush in the front hole of the U-shaped bracket. The 'step' diameter-change in the large-diameter shaft is what engages with the front top-hat bush and limits its ability to move forwards (the front top-hat bush being installed with the 'flange' on the inside of the U-bracket). I fear that yours has been 'got at' and has some elements of the tuning-spindle assembly missing.

24th Feb 2019, 10:34 am	#7
Humptydumpty Pentode Join Date: Aug 2010 Location: Bewdley, Worcestershire, UK. Posts: 191	Re: TRIO 9R-59DS Tuning Mechanism Question Most of these Trios will have this problem after some time . I would fit a block inside the [ u ] bracket to keep the shaft in on place. Or even two split , like one top and one on the bottom of the shaft .

24th Feb 2019, 10:42 am	#8
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: TRIO 9R-59DS Tuning Mechanism Question Perhaps a nearby member with a lathe could turn up a bush for the OP. It's a simple enough job, but requires access to the 'U' bracket and shaft to ensure an accurate fit. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

24th Feb 2019, 2:00 pm	#9
g4aaw pete Heptode Join Date: Jan 2008 Location: Birchington Kent, UK. Posts: 596	Re: TRIO 9R-59DS Tuning Mechanism Question Hello Alan had a look in my secret box of bearings & wonder if this item would be anywhere near required as a front bearing? Attached Thumbnails __________________ Regards Pete

24th Feb 2019, 2:41 pm	#10
snowman_al Octode Join Date: Dec 2018 Location: Llandeilo, West Wales, UK. Posts: 1,092	Re: TRIO 9R-59DS Tuning Mechanism Question A quick update to the post. First I wanted to keep it as original as possible, just in case I find a correct solution in the future. The outer 'band set' shaft is 11/32'' (8mm). I found an old 1/4'' (6.3mm) shaft support from my spares box so it need to be drilled out. (It was the only one with enough thickness I could find, then only just.) Then I filed the hexagonal section thin enough to fit between the U bracket and face plate. The steel chassis thickness in fact.) Next I shortened the threaded section to give just enough space between the band set knob and the front face plus 1/2mm for float. Unfortunately I will still have to use the knob to prevent the shaft sliding back, but that is now settable and I know it will not scuff the face plate. Only small problem is the nut to fit the support collar is not the correct thread, but will do until I can find the correct one. Pete, thanks for the offer. If this does not prove satisfactory, I will consider opening up the U bracket and face plate to take a bearing. I could well be back to you. Alan This is work in progress Attached Thumbnails __________________ Never Leave Well Enough Alone...

24th Feb 2019, 3:09 pm	#11
g4aaw pete Heptode Join Date: Jan 2008 Location: Birchington Kent, UK. Posts: 596	Re: TRIO 9R-59DS Tuning Mechanism Question Hello Alan by the looks of things, you've come up with a good fix. If you decide you'd like my bearing though, PM me your address & I'll post it to you. By the way, notice you're an ex-xeroid like myself! __________________ Regards Pete

24th Feb 2019, 5:21 pm	#12
snowman_al Octode Join Date: Dec 2018 Location: Llandeilo, West Wales, UK. Posts: 1,092	Re: TRIO 9R-59DS Tuning Mechanism Question Thanks everyone, Latest is:- I have put it all together, re-strung both dial cords and lined the pulleys and drive shafts up and it works as I would hope. Smooth enough, does not 'shoot' all over the place as you touch / turn the knobs and no interaction between the two dials. Just listening to the 40 metre contest as I report. A couple more oddities on this set to understand, but happy to give it some proper TLC now. Alan Attached Thumbnails __________________ Never Leave Well Enough Alone...