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Old 27th Dec 2011, 9:06 pm   #1
Pepelephew
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Default Bush AC34, no sound.

Hello all,

Working through my first restoration project on my Bush AC34. Have run into some trouble with the sound. I have replaced most wax capacitors and all valves, except the UL41. When powered up everything seems to be OK but not a peep from the speaker. There is some crackling when I connect/disconnect the speaker wires but nothing else
Any help would be appreciated as to where to start to look for the problem.

Thanks a mill
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Old 27th Dec 2011, 9:23 pm   #2
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Default Re: Bush AC34, no sound.

Right. Do you get any hissing or buzzing noises, quiet or loud? Are all the replacement caps put in right and how about the valves? (Why change valves on spec. by the way. They tend to be OK apart from the UL41.)

Go onto the middle pin of the volume control with a finger and see if it makes any noise. Is the speaker plug in OK?

Measure the voltages on the valves and report back.

Oh - You may need a big aerial with this set to get anything decent out of it.

Cheers,

Steve P.
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Old 27th Dec 2011, 10:11 pm   #3
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Default Re: Bush AC34, no sound.

Quote:
Originally Posted by Steve_P View Post
Right. Do you get any hissing or buzzing noises, quiet or loud? Are all the replacement caps put in right and how about the valves? (Why change valves on spec. by the way. They tend to be OK apart from the UL41.)
Yep I'd ask the same question. Valves are a dwindling resource and preserving current stocks within reason is paramount. It's fairly unlikely that the signal valves are faulty. Possibly the UL41 is as there are known problems that can develop over time. Try the tips that Steve has suggested. Please also measure some voltages and come back with your findings.



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Old 27th Dec 2011, 10:18 pm   #4
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Default Re: Bush AC34, no sound.

Thanks for the tips. I am back to work tomorrow but I will report back ASAP.
As regards the valve replacements, this is my first attempt at restoration and I suppose I thought I was doing the right thing. I have kept the old valves for future projects.
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Old 27th Dec 2011, 11:02 pm   #5
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Default Re: Bush AC34, no sound.

There's a loudspeaker switch on these which you should make sure is in the ON position. It's a knurled screw situated on a paxolin board at the rear of the set, top right. Make sure it's screwed down and making a good connection.
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Old 30th Dec 2011, 7:38 pm   #6
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Default Re: Bush AC34, no sound.

Hi all and thanks for your help,

I may have led you a bit astray, the model I have is a Bush Ireland radio very similar in appearance to the VHF54 with the green eye in the top left corner. It does not have VHF waveband, only L/M/S.

I tried the test on the volume control on the middle lug, but no joy. I am measuring the voltage on the valves at the moment but as I have no tech. knowledge I am not sure if I am doing it correctly; eg on UY41 I got a measurement of 120, on UL41, 100 on UBC41, 15 and 6 on the next one.

There are different coloured wires on each valve and using a multimeter can you tell me which colours are correct?

I have rechecked all the caps and they seem to be ok. I have also checked the sound mute screw on the top right corner and that's ok.
I'm not giving up.

Thanks,
Dill.
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Old 31st Dec 2011, 11:14 am   #7
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Default Re: Bush AC34, no sound.

Voltage readings on valve sets should be taken with the black negative lead of your meter connected to chassis with a croc clip. You can then use a probe on the red positive lead to connect to each valve pin in turn. Looking from UNDER the chassis, valve pins number clockwise from the gap or spigot.

Post the voltages on each pin here and someone will advise you.

I'm afraid that a visual check of a capacitor will not tell you if it's faulty unless it's been blown to bits or is leaking liquid. However faulty capacitors will show up as incorrect voltages.
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Old 31st Dec 2011, 12:51 pm   #8
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Default Re: Bush AC34, no sound.

Thanks Graham,
I will work away at that
Bill
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Old 31st Dec 2011, 12:56 pm   #9
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Default Re: Bush AC34, no sound.

Is this the same set as you asked about here?

https://www.vintage-radio.net/forum/...highlight=bs35

Andrew
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Old 31st Dec 2011, 1:23 pm   #10
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Default Re: Bush AC34, no sound.

Stop right there matey. If you don't know the basics then you shouldn't meddle.

Start here, read and learn...

http://www.vintage-radio.com/repair-...ion/index.html

Cheers,

Steve P.
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Old 31st Dec 2011, 1:48 pm   #11
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Smile Re: Bush AC34, no sound.

Hi,
Please be very careful. I'm not familiar with this set but as the valves are "U" types then the chassis will be connected directly to one side of the mains. This SHOULD be the neutral side, but isn't guaranteed. Remember that there is NO isolation between you and the mains. Ideally you should work on this set through an isolating transformer. But as it's unlikely you'll have one, then keep one hand in your pocket!
We want to keep our members as long as possible. As Steve says, read and learn. Good luck!
Cheers, Pete
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Old 31st Dec 2011, 1:57 pm   #12
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Default Re: Bush AC34, no sound.

Steve's right, do a little reading and learning first for your own sfatey and peace of mind.
If the set has been stored anywhere damp the output transformer could be suspect... they have a tendancy to green spot causing them to go open circuit on the primary side, just the same as DAC90A's. You'll see that is a common reported fault on here.
With the set turned off and unplugged you could measure its resistance which will tell you if it's kaput.
You should have been able to measue two pins on the UL41 with high voltage present... one (the anode) greater than the other.
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Old 1st Jan 2012, 8:05 pm   #13
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Default Re: Bush AC34, no sound.

Thank you all, Pete, Pete, Steve, Andrew,

I will follow your advice and read on. I will do my upmost not to blow myself to bits and keep my hand in my pocket. I will proceed with caution and report back.

Thanks again,
Bill
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Old 1st Jan 2012, 8:35 pm   #14
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Default Re: Bush AC34, no sound.

Quote:
Originally Posted by Tractorfan View Post
Hi,
Please be very careful. I'm not familiar with this set but as the valves are "U" types then the chassis will be connected directly to one side of the mains.
From the data I've been able to locate this model has a double-wound transformer despite the U-series valves.

The output transformer and speaker have a plug and socket arrangement which is another potential cause of trouble.

- Joe
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Old 1st Jan 2012, 9:26 pm   #15
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Default Re: Bush AC34, no sound.

Yes Joe,
Looking from the rear of the chassis there is a small plug and socket on the right hand side with 2 leads to the illuminating bulbs and 2 to the speaker transformer. All leads are frayed and will have to be replaced
Thanks
Bill
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Old 2nd Jan 2012, 12:45 am   #16
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Default Re: Bush AC34, no sound.

No Joe,
DC mains cannot be used with a transformer as shown in your diagram. It must be AC only with that circuit.
Trevor
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Old 2nd Jan 2012, 8:34 am   #17
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Default Re: Bush AC34, no sound.

Hi Trevor

The AC34 does have a mains transformer as Joe shows this set is not suitable for DC.
The AC/DC version of this set without a Mains Transformer is the DAC34.

If the set doesn't have the mains transformer then its not an AC34

You can examine the differences in Trader sheets 1147 and 1149

Enjoy

Mike T
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Old 2nd Jan 2012, 11:24 am   #18
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Default Re: Bush AC34, no sound.

My understanding is that this set is actually an export version ie a Bush BS35. As such it could be AC only or AC/DC. We need to know from the OP whether it has a mains transformer or dropper resistor. A picture of the internals would help.
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Old 2nd Jan 2012, 11:33 am   #19
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Default Re: Bush AC34, no sound.

Hi Mike/Trevor
when I started this i could not find proper id on the radio, it looked like a AC34 but on further investigation i found Type BS35 on the chassis . It is very similar in appearance to the VHF 54, with the green eye in the top left corner( to do with signal strength,which lights up when powered). there is a transformer on the chassis on the right hand side looking from the rear with another smaller transformer on the speaker. It does not have vhf waveband only LW/MW/SW.
Bill
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Old 2nd Jan 2012, 11:35 am   #20
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Default Re: Bush AC34, no sound.

Hi Graham ,
I will get some pics and post
Bill
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