Bush MB60, TR82, VTR103 and other variants

[Robert Darwent]

It depends which way you look at it, to a certain extent with that old plastic stuff it's in the lap of the gods.
If there happens to be the start of a feint hairline crack on the plastic boss then attempting to remove the knob by tension from the front is likely to make the crack worse which could lead to a total fracture

I can only report my actual experiences of removing the clear knob on 40+ sets using the cord method outlined earlier without a single breakage.

the risks of that are reduced if the knob is removed by compression using a couple of screw drivers from the back.

Again, I can't agree. Soft brittle plastic is always going to yield before unforgiving steel. Yes you'll get away with it on some occasions for sure. But if you've as many sets as I have had need to remove and clean the tuning knob on, you'd quickly switch from using screwdrivers or any other tool made from metal.

Regards

[Robert Darwent]

That is exactly what I was thinking of. The pressure is from the inside of the spring clip.
The clip stops the screwdriver from getting close to the boss. Any marks will be made on the inside of the boss on the edge and will be low risk as the clip will stop a crack forming.

It is true that the "clip stops the screwdriver from getting close to the boss" but equally the clip supports the plastic of the shaft whilst you are removing it with a cord as well. With a cord/plunger the majority of the pressure applied is straight upwards and you are using the entire diameter of the knob to distribute that pressure evenly. It's not the same situation when using two screwdrivers, you have two contact points focussing the pressure. One slip with either screwdriver, which is quite likely, and the pressure is suddenly one sided on the shaft.

In any event, to my way of thinking it's got to be far simpler and easier to slip a cord under the knob from the front of a complete set, than to take the back off and remove chassis screws in order to gain limited access with a pair of screwdrivers. Screwdrivers that when they slip could damage the metal dial, tuning capacitor or some other internal component. But each to his own preferred method of course.

Regards

[pwdrive]

Robert, I was just pointing out a trap for the unwary as regarding hairline cracks and applying tension, the screwdrivers used as a lever don't have to touch the plastic boss if you have a suitable interface.
The trick with the cord is to tie it into a loop so that each side of the loop goes either side of the tuning shaft, that way you can apply equal force either side of the tuning shaft which you can't really do with the single line cord method, It makes pulling easier too.
Not got 40 of the Bush types though, but have done hundreds of extractions on radios and TV's in my servicing days, some you win some you loose that's for sure.
Most got partly fractured by the customer...it falls apart in your hands...you take the blame..."Well it wasn't like that when I brought in for service""...Such is life.

Lawrence.

[Robert Darwent]

The trick with the cord is to tie it into a loop so that each side of the loop goes either side of the tuning shaft, that way you can apply equal force either side of the tuning shaft which you can't really do with the single line cord method, It makes pulling easier too.

Yes, correct Lawrence. I neglected to say that the cord should be tied into a loop in my earlier posts. That is exactly how it is done - with a looped cord.

Regards

[pwdrive]

Yes, getting some of those old dials/knobs off can be a pig, especially if some one has been in there with the switch cleaner spray in the past for whatever reason (plastic disintegration syndrome)

Lawrence.

[Refugee]

TR82 ear phone socket question.
When exactly were these fitted as I am confused.
Was it the late MK1 that had them as this appears to be so when I read message 1.
I have done a thread on a TR82D MK2 that is fitted with the ear phone socket. It is the AF117 variant with a 349 chassis.
I am confused as to the MK that they were fitted to.

[Robert Darwent]

TR82 ear phone socket question.
When exactly were these fitted as I am confused.
Was it the late MK1 that had them as this appears to be so when I read message 1.
I have done a thread on a TR82D MK2 that is fitted with the ear phone socket. It is the AF117 variant with a 349 chassis.
I am confused as to the MK that they were fitted to.

With regards the MK.I models using the A177 chassis;

TR82B (type 345) the earphone socket is absent.
TR82C (type 346) with a serial number less than around 15xxxx, the earphone socket is absent.
TR82C (type 346) with serial numbers of 15xxxx or greater, the earphone socket is present.
TR82D (type 508) the earphone socket is present.

Later when the Mk.II versions of the TR82C (type 528) and TR82D (type 530) were released using the A349 chassis, they had the earphone socket fitted as standard.

Regards

[Robert Darwent]

Another Variant - The ETR92T

Some will already be aware of my enthusiasm for collecting the various models in the Bush MB60/TR82 series and that I wrote an article on the subject entitled "Variations on a theme: The Bush MB60 family" which appeared in the Winter 2010 issue of the BVWS Bulletin magazine (pdf of which is attached to post #15 of this thread).

That article ended with the final paragraph speculating on the possibility of further model variants out there waiting to be unearthed as it were. I should now like to report on a further little known model to add to the series.

A few months ago I carried out an internet search with the intention of trying to find further images of the ETR92 export set. Rather unexpectedly instead on an image hosting website I came across a model with a similar type number, the ETR92T, that I hadn't heard of before.

There were several good close-up images showing a set which I initially wrongly assumed to be a "marriage" of two or three of the known models in the series. It will be appreciated that the majority of the plastic case parts and the various chassis themselves are interchangeable between the different sets.

My sceptism was because of the colour combination used by the ETR92T. It has the same light blue/green coloured plastic case plus the chrome trim and "B U S H" lettering that is found on the familiar TR82C. But the middle section instead of being blue has a red rexine covering, as used by the MB60 and EBM60 battery valve models.

After contacting the owner of the images and then more recently obtaining another example of the ETR92T myself from a different source, there is now no doubt that the set is indeed a genuine model. However, I still find the colour scheme a strange choice, hence my immediate thoughts that it had been assembled by someone using spare parts.

   

The type/serial number plate underneath the middle of the case states "Bush (Ireland)", the model being made at Bush's factory based in Dublin's northern suburb of Whitehall. Like the colour scheme this fact is also unusual, as all the other models in the series were produced at Bush's factories in England.

   

The set offers long wave, medium wave and one short wave band from 1.7 to 5.0 MHz.

   

With the three wavechange buttons labelled simply L, M and S.

   

The short wave range is considerably lower than those offered on the three export models (EBM60, ETR82 and ETR92), so presumably the "T" in ETR92T may stand for '"tropical bands".

Internally the chassis appears to be derived from the ETR92 variant. Apart from very minor differences in the number of coils and trimmers fitted due to the different wavebands offered, it looks to be virtually identical.

   

As with the more common TR82 sets, the model specifies the use of a 9 volt Ever Ready PP9 or equivalent, rather than the 6 x D cells used by the ETR92. This would suggest the ETR92T was produced as a domestic model, since the main reason for specifying D cells on the export sets (ETR82 and ETR92) was because of the limited availability of the PP9 battery overseas.

In view of the ETR92T coming to light, I have reworked my earlier model table in the article to include it. At the same time I have taken the opportunity to reclassify the models only according to Bush's type numbering system which has resulted in there now only being 14 "official" models despite the new addition.

01. 237 - MB60 - LW/MW, Valve, Light grey case, Red rexine, Brass trim - c.1957
02. 240 - EBM60 (Export) - MW/2xSW, Valve, Light grey case, Red rexine, Brass trim - c.1957
03. 345 - TR82B - LW/MW, OC transistors, Coffee case, Brown rexine, Brass trim - c.1959
04. 346 - TR82C - LW/MW, OC transistors, Blue/green case, Blue rexine, Chrome trim - c.1959
05. 355 - ETR82 (Export) - MW/2xSW, Valve/OC transistors, Blue/green case, Blue rexine, Chrome trim - c.1959
06. 421 - ETR92 (Export) - MW/2xSW, OC transistors, Blue/green case, Blue rexine, Chrome trim - c.1960
07. 438 - ETR92T - LW/MW/SW, OC transistors, Blue/green case, Red rexine, Chrome trim - c.1960
08. 462 - VTR103 - LW/MW/VHF, AF transistors, Cream case, Tan rexine, Chrome trim - c.1961
09. 508 - TR82D - LW/MW, OC transistors, Cream case, Tan rexine, Chrome trim - c.1962
10. 528 - TR82C Mk.II - LW/MW, AF transistors, Blue/green case, Blue rexine, Chrome trim - c.1963
11. 530 - TR82D Mk.II - LW/MW, AF transistors, Cream case, Tan rexine, Chrome trim - c.1963
12. 622 - VTR103C - LW/MW/VHF, AF transistors, Blue/green case, Blue rexine, Chrome trim - c.1964
13. 653 - TR82CL - LW/MW/208, AF transistors, Blue/green case, Blue rexine, Chrome trim - c.1964
14. 655 - TR82DL - LW/MW/208, AF transistors, Cream case, Tan rexine, Chrome trim - c.1964

Regards

[pwdrive]

Good research Robert.

Lawrence.

[Refugee]

I have just acquired a VTR103 for a tenner at the flea market.
It looks all there apart from the red bit on the aerial and a little bit of the front on the top right..
I think there will soon be a new thread from me.