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Bush TV32.

Pre War 240/405, Post War 405 Line, B&W Dual Standard, Colour Dual Standard, B&W S/S 625, Colour S/S 625 line, Hybrids. Standards converters & modulators, video recorders.
 
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Bush TV32.

Post by Till Eulenspiegel » Sat Aug 06, 2016 4:38 pm

I've commenced the restoration of a Bush TV32, the rarest of the Bakelite Bush TV sets.
I'm sure a service manual was issued for this set but there is no reference to the TV32 in the Radio and Television servicing books.
No problem, the five channel RF deck is similar to the one fitted in later Bush TV22 and TV24 receivers, EF80 pentodes instead of EF91s.
The timebases are similar to those in the TV43.
The decoupling capacitors in the heater chain of the RF deck have been replaced, done that job this morning. Unfortunately, on test there was a almighty bang and the fuses blew. There is a dead short across the mains connector terminals, it's likely the insulation of the wiring has broken down. Almost all the wires in this set are rubber insulated.
The chassis will have to come out but the front control knobs are stuck fast. I assume they are of the push on spring clip type. There certainly doesn't seem to be any holes for access to any screws that will secure the knobs.

Till Eulenspiegel.
Attachments
BushTV32.jpg

 
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Re: Bush TV32.

Post by marc » Sat Aug 06, 2016 5:00 pm

Till Eulenspiegel wrote:The chassis will have to come out but the front control knobs are stuck fast. I assume they are of the push on spring clip type. There certainly doesn't seem to be any holes for access to any screws that will secure the knobs.

Till Eulenspiegel.

Hi Till,

I didn't think that any of the Bush sets of this era had spring clip main controls knobs fitted :aaq

Marc.

 
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Re: Bush TV32.

Post by Till Eulenspiegel » Sat Aug 06, 2016 5:08 pm

Hi Marc,
just checked the front control knobs of my TV32 and these are of the push-on type. There is a Bakelite material coupler behind each front control shaft.

Till Eulenspiegel.

 
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Re: Bush TV32.

Post by CTV » Sat Aug 06, 2016 5:14 pm

Till Eulenspiegel wrote:I'm sure a service manual was issued for this set but there is no reference to the TV32 in the Radio and Television servicing books.
Till Eulenspiegel.

The Bush TV32 manufacturers service manual is available for download from Jon's website http://www.thevalvepage.com/tvmanu/bush/bush.htm

scroll to the bottom of the page for the TV32 manual link

 
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Re: Bush TV32.

Post by Till Eulenspiegel » Sat Aug 06, 2016 5:32 pm

Plenty brute force and the on-off volume knob has been released, and sure enough it's the spring clip type of fixing. Spring clip is rusty.
Now to tackle the brightness control.

Till Eulenspiegel.

 
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Re: Bush TV32.

Post by marc » Sat Aug 06, 2016 6:43 pm

Till Eulenspiegel wrote:Hi Marc,
just checked the front control knobs of my TV32 and these are of the push-on type. There is a Bakelite material coupler behind each front control shaft.

Till Eulenspiegel.

I see, so they have a sort of extension / coupler fitted between the pot and control knobs.....you live and learn :)

Marc.
Last edited by marc on Sat Aug 06, 2016 6:44 pm, edited 1 time in total.

 
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Re: Bush TV32.

Post by Derren » Sat Aug 06, 2016 6:43 pm

Hi Till,

Well done with the knob removal. Here is a photo of the actual set not long after I got it home. It has the knobs with the large 'skirt' around the outside, the type which I have rarely seen, I wonder if any forum member could throw any light as to why some sets had this type of knob? I do think they are rather attractive however. It's not that obvious in the photo but as you know the right hand knob is already part broken so could be a problem.
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13738108_10157169364740471_7938945595687342910_o.jpg

 
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Re: Bush TV32.

Post by Alistair D » Sat Aug 06, 2016 7:38 pm

CrustyTV wrote:
Till Eulenspiegel wrote:I'm sure a service manual was issued for this set but there is no reference to the TV32 in the Radio and Television servicing books.
Till Eulenspiegel.

The Bush TV32 manufacturers service manual is available for download from Jon's website http://www.thevalvepage.com/tvmanu/bush/bush.htm

scroll to the bottom of the page for the TV32 manual link


Anyone having a problem downloading from thevalvepage?
When I type the manufacturer's name into the prototype download system nothing happens.

Al

 
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Re: Bush TV32.

Post by Till Eulenspiegel » Sat Aug 06, 2016 8:06 pm

Hi Allistair,
It's the same here, can't download the TV32 service manual.

At last the brightness control knob has been removed but unfortunately it had to be butchered to remove it, thankfully the skirt around the knob has been saved. It should be possible to find a suitable replacement.
So now it's possible to remove chassis from the cabinet. That short circuit across the mains input must be traced first before any other work on the chassis can be done.

Till Eulenspiegel.

 
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Re: Bush TV32.

Post by Duke Nukem » Sat Aug 06, 2016 9:38 pm

Alistair D wrote:Anyone having a problem downloading from thevalvepage?
When I type the manufacturer's name into the prototype download system nothing happens.

Al


Yes it does seem bust - the server moved again recently, I suspect it's related.

In the meantime, Til if you need a copy of the manual I'll email you a copy.

TTFN,
Jon

 
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Re: Bush TV32.

Post by Till Eulenspiegel » Sat Aug 06, 2016 10:39 pm

The short circuit across the mains supply was a hidden 0.05mfd filter capacitor, it's been clipped out. The capacitor will be replaced later on.
The 0.01mfd coupling capacitor between the anode of the EF80 line oscillator and the grid of the PL81 was as expected found to be leaky, now replaced.
Removing the chassis: In the TV32 the CRT is mounted on the cabinet and not on the chassis. Before the chassis can be taken out the ion trap and the chassis mounted focus magnet assembly must be removed. The CRT might possibly be the original MW36-24 because the final anode connector is a 7mm cap instead of the more common ct8 cavity connection. This CRT has the tetrode gun assembly, the CRT installed in my TV32 is a MW36-44 which has the pentode gun.

Till Eulenspiegel.

 
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Re: Bush TV32.

Post by Till Eulenspiegel » Sat Aug 06, 2016 10:49 pm

Duke Nukem wrote:
Alistair D wrote:Anyone having a problem downloading from thevalvepage?
When I type the manufacturer's name into the prototype download system nothing happens.

Al


Yes it does seem bust - the server moved again recently, I suspect it's related.

In the meantime, Til if you need a copy of the manual I'll email you a copy.

TTFN,
Jon

Hi Jon,
thanks for that, however, I think the TV43 service data in the 1953/54 R & T servicing book will provide sufficient information to complete the restoration of this set.

Till Eulenspiegel.

 
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Re: Bush TV32.

Post by Spot-Wobble » Sun Aug 07, 2016 12:01 pm

I have a TV32 also, It has had the additional tuner fitted (by cutting out part of the back panel).
I seem to remember that it has a re-gunned tube fitted.
I did try to remove the chassis from the case but couldn't find out how to do it.
Not the same as the TV22. A post on the forum didn't get any replies at the time - a couple of years ago now.

At the moment the set is all packaged up in protective cardboard along with all the rest of the sets for when they were moved here to France.

Good luck with the restoration.

Andy

 
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Re: Bush TV32.

Post by Till Eulenspiegel » Mon Aug 08, 2016 8:19 pm

The line drive waveform is present at pin2 of the PL81 but there was no spark at the anode of the EY51 EHT rectifier. Replaced the PL81, I've got 9KV EHT now but there was absolutely no illumination on the screen whatsoever. The brightness control was adjusted so the CRT grid volts are the same as the cathode, = no bias volts between grid and cathode. First anode volts are 240, a bit low but should be OK. No amount of adjustment of the ion trap magnet would induce the tube to produce any light. Out with the tube reactivator, give the tube a tickle, that seems to have done the trick, now we have a bright line across the screen. It's likely many more capacitors in the frame timebase will have gone bad. I'll replace them and report back.

Till Eulenspiegel.

 
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Re: Bush TV32.

Post by Katie Bush » Mon Aug 08, 2016 10:13 pm

"Tube reactivator"?...... :elc:


Eeek!... :ccf

 
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Re: Bush TV32.

Post by Till Eulenspiegel » Mon Aug 08, 2016 11:19 pm

Hi Marion,
The 1980s Muter tube tester and reactivator was pressed into service. This instrument was considered in it's time to be one of the best tube testers available. Processes colour and B & W tubes.
It's possible that the Mullard MW36-24 has that old problem which is well known in tubes of that make, a partially shorted heater.

Till Eulenspiegel.

 
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Re: Bush TV32.

Post by Katie Bush » Mon Aug 08, 2016 11:33 pm

Hi Till,

I too have a Muter, but a quick glance under faceplate revealed a pair of low wattage bulbs in what at first glance looked like a glorified "bopper" - I tried it once, on an unimportant CRT, and saw a fireworks display in the CRT neck.. I felt it to be a bit violent for my liking.

Marion

 
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Re: Bush TV32.

Post by Till Eulenspiegel » Tue Aug 09, 2016 1:04 am

Hi Marion,
In fact that's all the Muter is and just like other tube testers a bulb in series with the grid of the tube under test supplies the "controlled" current between the cathode and grid or to give it's archaic name the Wehnelt electrode.
The only saving grace for the Muter is that during the reactivation process the heater supply to the tube is switched off, by doing this it is claimed by the makers of the instument to prevent the cathode from being destroyed during the reactivation process.
Anyway, be that as it may, the instrument has revived the CRT in the Bush TV32.

Till Eulenspiegel.

 
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Re: Bush TV32.

Post by Till Eulenspiegel » Tue Aug 09, 2016 7:43 pm

The frame timebase is now working albeit a slight compression at the bottom of the picture. The RF deck has been retuned to channel B1 and didn't require any further work done on it to get it going although later on all the anode and screen grid waxie decoupling capacitors will be replaced. The unit delivers adequate audio drive to the PL83 sound output valve and more than 50 volts P - P video to the CRT cathode.
The CRT is not good, the picture is dim, in fact it's lights out to view the picture. The tube's heater measures only 4 volts between pins 1 and 12 proving it has a partially shorted "M" type heater. Replacement is the only answer if a perfect picture is to be achieved and the set is well worth a replacement tube if one can be found.
So now I'm on the lookout for an MW36-24 or equivalents like the MW36-44 or 14LP4. All these tubes are becoming difficult to find. The electrostatic focus AW36-20 can also be considered.

Till Eulenspiegel.


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