Bush AC34 Help with Tuning - UK Vintage Radio Repair and Restoration Discussion Forum

meolskopite · 1st Mar 2016, 9:58 pm

Hi

I have just bought my first vintage radio (after being an SWL for a number of years) but have a problem with the Bush AC34 tuning "pulleys" (Sorry I don't know the correct name).

While I can open the radio up and manually tune it, the pulley wire that would normally allow it to be tuned by the knob is always too slack and I am not sure the route it should take.

Can anyone help?

The radio seems fine otherwise, bulb works, band switch works, volume/speaker all OK but wish I could tune it.

Thanks
Stephen

paulsherwin · 1st Mar 2016, 10:10 pm

The tuning cord has snapped and needs to be replaced. A number of materials can be used to replace the cord but monofilament fishing line is probably the easiest to obtain.

The radio appears to be completely unrestored and you would be unwise to continue to use it in this state. It is unlikely to perform well anyway.

Station X · 1st Mar 2016, 10:10 pm

Hello and welcome to the forums.

The information you require will be found in the service sheet which can be downloaded here:-

http://www.service-data.com/product.php/574/904/m10574

gary_crutchley · 1st Mar 2016, 10:25 pm

Hi Stephen,

I have one of the sets, they do work very well. It looks as though the dial cord has either come off the pulleys or has broken. You will need to extract the chassis from the case and either refit the cord or fit a new one. It will probably be easier to fit a replacement.

If you download the manufacturer's data sheet (not the trader sheet) from the link above, there is a detailed diagram on page 4, together with instructions on how to fit the cord.

Before you take the chassis out of the case remember to release the two pointer drivers from the tuning scale. They are attached to the cord and will need to be fitted to the replacement. There should also be a small spring in the end of the cord which is attaches to the drive drum and tensions the cord. If it's not on the cord check the case for it.

Replacement drive cord can be purchased on eBay, it's relatively cheap.

If the set hasn’t been used for a long time and is in original condition, it’s advisable not to apply mains straight away. There are a number of checks that need to be done and several components that will have suffered from the effects of ageing, these will need replacement. Once you’ve refitted the dial cord come back for more advice, there are lots of people on here who will help.

I hope that this helps, let us know how you get on.

Regards,

Gary

meolskopite · 2nd Mar 2016, 7:30 pm

Hi Gary,

Yes I think the drive cord has come off but doesn't appear to be broken. Later tonight or tomorrow I will try and put it back into place.

Thanks for the tip about the data sheet, page 4 is very helpful and shows that when I was trying to put it back on previously I wasn't winding it properly. You are right though I need to take the chassis out to get it on.

I have plugged it in and turned it on already, I tuned through the medium wave band and SW band hearing Talksport, 5Live, IRIB Iran, Radio Romania by manually moving the drive drum. Hopefully I haven't damaged anything by doing that!

Stephen

AC/HL · 2nd Mar 2016, 9:32 pm

The main problem with radios of this age is not the valves, as popularly thought, but the capacitors. Paper capacitors become electrically leaky. One in particular, the output valve grid coupling capacitor, has the potential to cause damage. Use the search box above to look for "That Capacitor", a nickname given on account of this.

gary_crutchley · 6th Mar 2016, 12:56 am

Quote:

Originally Posted by meolskopite

Yes I think the drive cord has come off but doesn't appear to be broken. Later tonight or tomorrow I will try and put it back into place.

Thanks for the tip about the data sheet, page 4 is very helpful and shows that when I was trying to put it back on previously I wasn't winding it properly. You are right though I need to take the chassis out to get it on.

Hi Stephen,

I haven't had to reinstall the drive cord on my set, so I don't know how difficult it is. You might be able to refit the original or it might be that you need a new length of dial cord. I've done other sets and some can be quite tricky.

However, I agree with Bill above, at a very minimum you should replace the output valve grid coupling capacitor. If it helps my effort to do this is documented here:

https://www.vintage-radio.net/forum/...d.php?t=116986

It is very easy to do, so I would recommend it. The UL41 valve on this set is becoming more rare and more expensive. Changing "that cap" will help to protect it.

Best regards,

Gary

1st Mar 2016, 9:58 pm	#1
meolskopite Retired Dormant Member Join Date: Mar 2016 Location: Southport, Lancashire, UK. Posts: 2	Bush AC34 Help with Tuning Hi I have just bought my first vintage radio (after being an SWL for a number of years) but have a problem with the Bush AC34 tuning "pulleys" (Sorry I don't know the correct name). While I can open the radio up and manually tune it, the pulley wire that would normally allow it to be tuned by the knob is always too slack and I am not sure the route it should take. Can anyone help? The radio seems fine otherwise, bulb works, band switch works, volume/speaker all OK but wish I could tune it. Thanks Stephen Attached Thumbnails

1st Mar 2016, 10:10 pm	#2
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,947	Re: Bush AC34 Help with Tuning The tuning cord has snapped and needs to be replaced. A number of materials can be used to replace the cord but monofilament fishing line is probably the easiest to obtain. The radio appears to be completely unrestored and you would be unwise to continue to use it in this state. It is unlikely to perform well anyway.

1st Mar 2016, 10:10 pm	#3
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Bush AC34 Help with Tuning Hello and welcome to the forums. The information you require will be found in the service sheet which can be downloaded here:- http://www.service-data.com/product.php/574/904/m10574 __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

1st Mar 2016, 10:25 pm	#4
gary_crutchley Heptode Join Date: Apr 2013 Location: Bloxwich, West Midlands, UK Posts: 554	Re: Bush AC34 Help with Tuning Hi Stephen, I have one of the sets, they do work very well. It looks as though the dial cord has either come off the pulleys or has broken. You will need to extract the chassis from the case and either refit the cord or fit a new one. It will probably be easier to fit a replacement. If you download the manufacturer's data sheet (not the trader sheet) from the link above, there is a detailed diagram on page 4, together with instructions on how to fit the cord. Before you take the chassis out of the case remember to release the two pointer drivers from the tuning scale. They are attached to the cord and will need to be fitted to the replacement. There should also be a small spring in the end of the cord which is attaches to the drive drum and tensions the cord. If it's not on the cord check the case for it. Replacement drive cord can be purchased on eBay, it's relatively cheap. If the set hasn’t been used for a long time and is in original condition, it’s advisable not to apply mains straight away. There are a number of checks that need to be done and several components that will have suffered from the effects of ageing, these will need replacement. Once you’ve refitted the dial cord come back for more advice, there are lots of people on here who will help. I hope that this helps, let us know how you get on. Regards, Gary __________________ http://www.crutchleyhistory.co.uk/

2nd Mar 2016, 7:30 pm	#5
meolskopite Retired Dormant Member Join Date: Mar 2016 Location: Southport, Lancashire, UK. Posts: 2	Re: Bush AC34 Help with Tuning Hi Gary, Yes I think the drive cord has come off but doesn't appear to be broken. Later tonight or tomorrow I will try and put it back into place. Thanks for the tip about the data sheet, page 4 is very helpful and shows that when I was trying to put it back on previously I wasn't winding it properly. You are right though I need to take the chassis out to get it on. I have plugged it in and turned it on already, I tuned through the medium wave band and SW band hearing Talksport, 5Live, IRIB Iran, Radio Romania by manually moving the drive drum. Hopefully I haven't damaged anything by doing that! Stephen

2nd Mar 2016, 9:32 pm	#6
AC/HL Dekatron Join Date: Nov 2003 Location: Heckmondwike, West Yorkshire, UK. Posts: 9,642	Re: Bush AC34 Help with Tuning The main problem with radios of this age is not the valves, as popularly thought, but the capacitors. Paper capacitors become electrically leaky. One in particular, the output valve grid coupling capacitor, has the potential to cause damage. Use the search box above to look for "That Capacitor", a nickname given on account of this.