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Radio Bush RG34 Radiogram (or Making a big ol bush look pretty again)

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Anonymous
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It was a bit of a long way for me.
I am often quite good at doing awkward jobs.

Simon thank you again for your offer I may still pop in if I am up your way for a chat or some pointers :)

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Topic starter Posted : 26/11/2012 9:17 am
sideband
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Today has been a good day. I had a visitor who has taught me more in his time here than I could ever have possibly learnt in a month os Sundays.

Andrew thank you so much for the time you have given, your patience, your bits and bobs to get the old girl running and your enthusiasm and encouragement towards me meaning that I will dive headlong into this great hobby.

I will post up some pictures of the progress so far when I get to the computer tomorrow.

Great news and I'm glad your radiogram is now coming along nicely.

One-to-one tuition is undoubtedly the best way to start with and Andrew has no doubt been a great inspiration. You never stop learning in this hobby and even people who have been in the trade for many years (I did nearly 40) still learn new things about this old technology. So glad you've gained more insite into 'what we do'. You'll be doing TV's next..........! :=D

Rich.

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Posted : 26/11/2012 10:23 am
Anonymous
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Sounds like you have definitely caught the bug now, it wont be long before you have a house full, as you yearn for new challenges.
Mike

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Topic starter Posted : 26/11/2012 10:26 am
Anonymous
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Mike and Rich thank you and I agree more projects will begin, There is an old TV with the guy who I got the bush from hmmmmm....

No Graham, step away from the TV you know the wife will kill you.

Some new wiring added

A few bits replaced

Valve re-introduced

unfixed the fix

And she's ready to go

Just got to refit in the case connect up the Garrard and give her a proper testing before I begin on the wood strip. I'm a happy bunny.

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Topic starter Posted : 26/11/2012 10:49 am
sideband
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There is an old TV with the guy who I got the bush from hmmmmm....

No Graham, step away from the TV you know the wife will kill you.

That's what we all say..... just one TV, then the Aurora standards converter, then another TV ...... wanders off mumbling........ :=D

Rich

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Posted : 26/11/2012 12:15 pm
Andrewausfa
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Hi Graham,

It was an absolute pleasure to help out and I'm really glad to see you found the time useful. The radiogram will look wonderful when fixed. Sorry to have left you with a shopping list :) Thanks for the Leak, it has a blown fuse in the RH channel which would obviously stop it working on that side.

On my visit I didn't want to leave you with a head full of theory or anything like that - meter ohms per volt, what they components do etc etc, I'm sure you're entirely capable of reading up for yourself as and when you need to. Like when you come to build your valve amp! :)

Just as a recap for Graham on the work we did in preparation to applying power;

Before powering up.

We replaced the four wires from the output valve via the four pin chassis plug to the output transformer which had crumbling insulation. We also did the two wires connecting between the Paxolin socket board, which must go on the back of your 'gram and the aerial sockets on the chassis. We taped over the small bits of crumbling on the supply wires to the dial lamps.

We taped over the exposed wires on the supply lead to the record deck. Rightly or wrongly I assumed this lead would carry 240v once the mains switch was 'on'.

Once we did the replacement wires, we checked the windings of the output transformer with a DMM set on the resistance ranges. This gave us the scratching noises in the speaker so we assumed the transformer and the speaker were OK. We then changed the tone correction capacitor that sits on top of the transformer.

We then used the meters continuity range (the beeper) to check the integrity of the mains lead, each pin to the switch on the back of the volume pot. We then checked, with the switch 'on', between the mains plug 'Live' pin and chassis to make sure there was no connection (open circuit). With the meter set to a low resistance range we then checked for continuity with the mains switch off and on. No reading on the former and a reading on the latter.

We checked the big electrolytic can by putting the meter on the highest resistance range and checked the reading(s) rose.

Under the chassis we looked for signs of components under stress (large HT smoothing resistor on the tag board looked a bit black though they usually do - R24 Trader sheet. Graham if you replace this I think you need a modern 5W 10k resistor), signs of any crumbling wire insulation, dry joints and any previous re-work.

Before we started replacing passive components I spoke about the differences between the two mains sets of service data, the Trader sheets and the manufacturers sheets which mainly amount to different numbers for components. We then looked at the circuit diagram and reviewed how British wireless diagrams normally work from the left to right, with the aerial circuits at left and the power supply circuits at the right. I then spoke about the AVC line usually being shown below the bold negative line at the bottom of diagrams. That done we looked for the AF coupling capacitor between V3 and V4 fired up the soldering iron and replaced it.

We then were in a position to give the set some power. We checked under and around the chassis for tools and bits of wire, removed anything and made sure all the other wiring and dial lamp brackets etc etc were away from the chassis.

We then connected the lamp limiter via an RCD to the mains and then plugged the set into the limiter. The set and lamp limiter were turned on, with the bulb switched into circuit and the reset button was pressed on the RCD which allowed power into the set.

After powering up and with a finger hovering over the RCD 'test' button.

We watched for smoke, smelt for melting transformer windings and listened for any untoward noises.

We switched off and checked the main electrolytic wasn't getting hot.

Just out of interest the voltage between the diode and reservoir capacitor was 324v. I think with the UY41 in place it should be around 265 volts. I should also add a thanks to Terry for the 're-wiring' diagram though I didn't see it until today. The person who'd implemented the diode/resistor combination had left one of the wires in place negating the need for any new wires. I was too slow to spot this and wired it as per Terrys diagram but wasn't slow to spot it when I switched the set on via the lamp limiter! I would imagine that was the fastest that radiogram has ever been on and off in its life.

Anyway, I had to go home at some point and I've left Graham with enough capacitors to finish the set.

There's a few things I would have like to addressed but ran out of time.

1) Set is fitted with a modern flat 2-core mains lead. This needs replacing with 3-core with the earth going to chassis. I've never done a radiogram but members can advise if an additional earth wire should go between the record deck and the chassis for safety. 2) we only had a 10 foot bit of wire hung over the door but sensitivity on MW seemed low 3) Volume seemed low despite the knob being wound up. I suspect this may improve when the coupling and negative feedback capacitors connected to the volume control are replaced. Not sure. 4) the volume pot is scratchy and needs a clean. It's also slightly loose on its track.

I thought I'd bring along a bunch of stuff along just to show Graham what they are and the differences. Again as an aide-de-memoire

On the meter front

Toolzone digital multimeter (DMM). This one is a £20 Far East cheapie but has a very large LCD screen, ohms range up to 200MOhm, capacitance up to 20uF, continuity tester (beep) and a transistor checker. This was the one we used the most. I've upgraded the leads to decent ,branded, ones and I pointed out to Graham the importance of this. Cost for this type £20-30 plus £15 to 20 for some good leads plus some insulated croc clips.

AVO 8 Mark 6 multimeter: this was the large one in the leather case. This is a late version of this meter but of the type most of the voltage readings on the service sheets would have been taken with. Cost £5 - £100+. A nice meter to have but not really necessary at first. If you see a boot sale bargain grab one but make sure the meter movement is working.

Fluke 25 multimeter (DMM): this was the chunky green one. This one is auto-ranging. Flukes are very expensive meters new and can be pricey second-hand.

Megger Insulation tester. This was the thing we tested the capacitors with - new ones versus the old wax ones. Not necessary at all. Mine was battery operated but you may find the older green or brown ones with the handle on the side at boot sales cheap. Don't forget these test at 500 - 1000V and can give you a nip.

Also the Lamp limiter and the Capacitor reformer: This was the silver box. Used for reforming electrolytic capacitors at rated voltage (240/350 volts).

The soldering iron we used was an Antex CS18 18w and I use 0.7mm 60/40 solder. Both of those are my preferences. If you want to solder to chassis - some components are soldered to chassis - then you'll need a bigger beast than an 18w iron. Something along the lines of 60w.

The capacitors we used were Vishay MKT1813 rated at 630v.

All the very best for your future endeavours. Now back to forensics....

Andrew

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Posted : 26/11/2012 10:04 pm
Refugee
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It is good to see that we are on the go with the bush.
I am looking forward to seeing the pictures of it all done.

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Posted : 26/11/2012 11:42 pm
Anonymous
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What Andrew said :)

I knew all that, no, really, I just didn't want to bore you all with the details HONESTLY :) ahem.

OK at the time I could understand what we were doing and also why we were making the checks. As I said he was very thorough in going through everything and apart from the 'wire' incident when the limiter bulb lit up like a christmas tree everything went as it should have done. Andrew was a little perplexed for about 30 seconds and then spotted the mistake pretty much straight away.

Thanks again Andrew for a great day. I hope the Amp will now sing and perform well for you.

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Topic starter Posted : 27/11/2012 10:23 am
Terry
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... The person who'd implemented the diode/resistor combination had left one of the wires in place negating the need for any new wires. I was too slow to spot this and wired it as per Terrys diagram but wasn't slow to spot it when I switched the set on via the lamp limiter!

Andrew, I've read and re-read this several times but I still can't get my head round it.

You appear to be saying that you added a new wire in parallel with one of the the original wires, which is very obvious not the case!

Can you expand on what was wrong that caused a problem?

I assume that this is what Graham referred to as "the 'wire' incident" ...

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Posted : 27/11/2012 11:41 am
Andrewausfa
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Hi Terry,

Sorry for the brief reply, in from work and straight out tonight. I think you're reading that I left a new wire in place, which isn't what happened.

In your diagram titled 'reinstatement of UY41' that wire you have as 'add' from pin 7 to capacitor was already there. You can see the wire in Grahams photos like a 'C' on it's side in brown Systoflex. Stupidly, I just didn't read the circuit properly and didn't spot the connection under the other wiring around the valve and added a wire from the point the diode (anode, the flat end of the 'bullet' to be clear) was connected to, pin 2, to the capacitor. Took me a split second to realise I'd cocked up and switch off, a few more seconds to reflect and another few seconds to remove 'my' wire and return the set to what is now or as it should be in your diagram.

Hope that makes sense

Andrew

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Posted : 27/11/2012 8:05 pm
Terry
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Ah! Got it! So you were trying to breed a new variety of AC Electrolytic, then .... :=D

I could see that one end of what you say was the original wire was connected to the cap but the UY41 end is hidden from sight, so it wasn't possible to know that it was still connected as there obviously had to be other connections to the capacitor somewhere!

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Posted : 27/11/2012 9:15 pm
Katie Bush
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That's what we all say..... just one TV, then the Aurora standards converter, then another TV ...... wanders off mumbling........ :=D

Rich

Nah... It's just not possible to have just one telly.. They get to you, they're insideous in their way, and really appeal to the hoarder in you.. The there's the mystery of "was it put away in working order, or was it put away 'dead' all those years ago" and you just have to find out.. Then there's the ultimate challenge of getting pictures and sounds out them.

Don't forget also, a standards converter is an expensive piece of kit, so you absolutely must justify it by having loads of tellies to use it on..

In three years, I've gone from none, to nine 405 lines, three dual standard, and two vintage colour.

Nah... It's just not possible to have just one telly...........

Marion

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Posted : 28/11/2012 1:10 am
Anonymous
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Marion stop it I do not want a tele. It's bad enough with the turntables and amps. Now it's valve radios already the second is waiting in the wings. If I were to do another deal with the man in the shop and bought home the 1940/50 tele he has hidden away in the corner I know the wife would leave me. I'm already thinking how can I get the other radio home that he has. Oh and today I was shown an old Ducati radio picture. That was my lunch hour gone googling Ducatis and seeing if there were any available on the bay of evils.

I mean why?

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Topic starter Posted : 28/11/2012 1:50 am
sideband
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I'm already thinking how can I get the other radio home that he has. Oh and today I was shown an old Ducati radio picture. That was my lunch hour gone googling Ducatis and seeing if there were any available on the bay of evils.

I mean why?

...it's happening!! Each vintage set you see will haunt you. When you walk away you'll be thinking 'Could I have saved it'? You'll resort to sneaking them in at odd hours under cover of darkness.......!

Rich

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Posted : 28/11/2012 9:56 am
Andrewausfa
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And keeping them in the boot of the car...and the loft...and in the cupboard under the stairs behind some other stuff...and magically a small piece of test equipment appears in the cupboard where the ironing board is kept. Don't forget the magic phrase when she spots something new, 'Nah! I've had it for ages'.

I write this as the missus hovers not two feet from the door, quick press 'Submit' before she comes in!

Andrew

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Posted : 28/11/2012 3:31 pm
Refugee
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I did a thread about sneaking sets in a few months ago :D

viewtopic.php?f=17&t=2442

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Posted : 28/11/2012 8:48 pm
Anonymous
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You lot are a nightmare I have officially been warned of divorce if I bring a tele home

My nephew is studying electrics at college at the moment so I do have an ally however when I mention valve radios he throws his hands up in despair. Even our youngest isn't interested.

Ah we'll it's just me and the dog.

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Topic starter Posted : 28/11/2012 10:51 pm
Anonymous
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You need a specially adapted set of tools for the dog.

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Topic starter Posted : 28/11/2012 11:52 pm
Anonymous
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I agree, a drinks holder for the rum n coke and a pouch to bring me the ciggies :)

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Topic starter Posted : 28/11/2012 11:55 pm
Anonymous
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I've had a long weekend and I've done all that I will do to the Big Bush.

The top has been stripped and oiled and looks pretty good I could go further here but I like the finish and I don't want to have it looking too shiny like new.

Before

After

The Bush radio has been refitted and works lovely on all channels

The Garrard auto changer works lovely and whilst I only have a couple of old scratched 78's in my collection the sound of them playing is fantastic and old school

The whole experience has been great both doing the work on her and chatting to you lot and meeting Andrew.

Just need to receive the knobs from Jamie (thank you again) and its ready to go to my Dad for his Christmas pressie. He has plenty of old mono records and 78's

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Topic starter Posted : 11/12/2012 4:45 pm
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