Bush AC41 - help with repair - UK Vintage Radio Repair and Restoration Discussion Forum

ChrisBU · 22nd Apr 2009, 12:59 am

Hi, I'm new here and new to delving into the inside of old radio's. I am familiar with valves and high voltages as I make and repair guitar amps. I have just obtained a Bush AC41 which I intend to use as my workshop radio. It works but I can't pick up any stations on MW, can just about hear R4 on LW and a couple of stations are quite strong on SW. I do have service info but I am asking here incase this is something commonly known to go wrong with these. I am not sure if it's low on RF or AF, I can get a hum out of it via the Gram input but it's not as loud as I would expect for a 3 watt output. When I get a spare hour I'll check voltages against the service data. I just hope I don't need to replace valves as they don't seem easily available.

julie_m · 22nd Apr 2009, 7:20 am

Check the ECH42 is oscillating when on MW.

Set the AC41 to MW and tune it to the bottom of the band (540 kHz. or 550 m.) Get a battery portable set and tune it to a weak station near the top end of the band (above 1000 kHz., or below 300 m.) Place the battery set next to the AC41 and slowly advance the AC41 tuning control. If the battery set goes quiet at some point (when the oscillator frequency of the AC41, which is the tuned frequency plus the IF, which should be 470kHz for this set, becomes equal to the tuned frequency of the portable), this proves the oscillator in the AC41 is running.

If no oscillation, then clean the MW / LW / phono selector switch contacts thoroughly before suspecting the coils. Circuit diagram available up top if you get stuck!

slidertogrid · 22nd Apr 2009, 8:17 am

Hi Chris
If the set is still fitted with its original wax capacitors you will need to change them all, most will be leaky by now, I havn't worked on a AC41 before but if its built in the usual Bush manner they will usually be mounted on a tagstrip under the chassis, If the set has any Brown "Hunts" caps change them as well.
There have been many discussions about this subject, a search should provide all the info you need.

Rich.

Radio_Dave · 22nd Apr 2009, 10:43 am

Yes, this radio will be full of brown, crumbly, Hunts capacitors that will need changing. Buy some service data (above right

) and identify their values before removing them as they'll disintegrate when touched!

There's also wax caps that'll need changing too, but it will probably work a lot better once re-capped

David

GrimJosef · 22nd Apr 2009, 7:15 pm

Hi Chris,

Welcome to the forum ! I'd have sent you a PM about this, but your PMs aren't enabled yet, so I can't.

Anyway if you need any bits, including valves, you might want to check my post here https://www.vintage-radio.net/forum/...ad.php?t=39373. The only cost for the radio itself would be getting it to you. I can transport it for free as far as the NVCF on May 10th (see here https://www.vintage-radio.net/forum/...ad.php?t=39589 and http://www.nvcf.org.uk/). If you're interested in it then maybe someone from your part of the world could collect it from me there and deliver it to you ?

Cheers,

GJ

ChrisBU · 25th Apr 2009, 5:26 pm

Well it seems my workshop is in a poor reception area. Even with 25 feet of wire aerial it doesn't pick up anything but the strongest signals. I replaced the caps and a resistor which didn't make any difference, then I took it home and connected it to a CB aerial on a mast and it works ok. I'll dig out my old RF sig gen and check alignment just for the satisfaction of knowing it's all as it should be.

22nd Apr 2009, 12:59 am	#1
ChrisBU Retired Dormant Member Join Date: Apr 2009 Location: Fakenham Posts: 10	Bush AC41 - help with repair Hi, I'm new here and new to delving into the inside of old radio's. I am familiar with valves and high voltages as I make and repair guitar amps. I have just obtained a Bush AC41 which I intend to use as my workshop radio. It works but I can't pick up any stations on MW, can just about hear R4 on LW and a couple of stations are quite strong on SW. I do have service info but I am asking here incase this is something commonly known to go wrong with these. I am not sure if it's low on RF or AF, I can get a hum out of it via the Gram input but it's not as loud as I would expect for a 3 watt output. When I get a spare hour I'll check voltages against the service data. I just hope I don't need to replace valves as they don't seem easily available.

22nd Apr 2009, 7:20 am	#2
julie_m Dekatron Join Date: May 2008 Location: Derby, UK. Posts: 7,735	Re: Bush AC41 - help with repair Check the ECH42 is oscillating when on MW. Set the AC41 to MW and tune it to the bottom of the band (540 kHz. or 550 m.) Get a battery portable set and tune it to a weak station near the top end of the band (above 1000 kHz., or below 300 m.) Place the battery set next to the AC41 and slowly advance the AC41 tuning control. If the battery set goes quiet at some point (when the oscillator frequency of the AC41, which is the tuned frequency plus the IF, which should be 470kHz for this set, becomes equal to the tuned frequency of the portable), this proves the oscillator in the AC41 is running. If no oscillation, then clean the MW / LW / phono selector switch contacts thoroughly before suspecting the coils. Circuit diagram available up top if you get stuck! __________________ If I have seen further than others, it is because I was standing on a pile of failed experiments.

22nd Apr 2009, 8:17 am	#3
slidertogrid Octode Join Date: Apr 2005 Location: Peterborough, Cambridgeshire, UK. Posts: 1,898	Re: Bush AC41 - help with repair Hi Chris If the set is still fitted with its original wax capacitors you will need to change them all, most will be leaky by now, I havn't worked on a AC41 before but if its built in the usual Bush manner they will usually be mounted on a tagstrip under the chassis, If the set has any Brown "Hunts" caps change them as well. There have been many discussions about this subject, a search should provide all the info you need. Rich. __________________ The rotation of the earth really makes my day...

22nd Apr 2009, 10:43 am	#4
Radio_Dave Nonode Join Date: Jun 2004 Location: Norwich, Norfolk, UK. Posts: 2,543	Re: Bush AC41 - help with repair Yes, this radio will be full of brown, crumbly, Hunts capacitors that will need changing. Buy some service data (above right) and identify their values before removing them as they'll disintegrate when touched! There's also wax caps that'll need changing too, but it will probably work a lot better once re-capped David

22nd Apr 2009, 7:15 pm	#5
GrimJosef Dekatron Join Date: Sep 2007 Location: Oxfordshire, UK. Posts: 4,311	Re: Bush AC41 - help with repair Hi Chris, Welcome to the forum ! I'd have sent you a PM about this, but your PMs aren't enabled yet, so I can't. Anyway if you need any bits, including valves, you might want to check my post here https://www.vintage-radio.net/forum/...ad.php?t=39373. The only cost for the radio itself would be getting it to you. I can transport it for free as far as the NVCF on May 10th (see here https://www.vintage-radio.net/forum/...ad.php?t=39589 and http://www.nvcf.org.uk/). If you're interested in it then maybe someone from your part of the world could collect it from me there and deliver it to you ? Cheers, GJ

25th Apr 2009, 5:26 pm	#6
ChrisBU Retired Dormant Member Join Date: Apr 2009 Location: Fakenham Posts: 10	Re: Bush AC41 - help with repair Well it seems my workshop is in a poor reception area. Even with 25 feet of wire aerial it doesn't pick up anything but the strongest signals. I replaced the caps and a resistor which didn't make any difference, then I took it home and connected it to a CB aerial on a mast and it works ok. I'll dig out my old RF sig gen and check alignment just for the satisfaction of knowing it's all as it should be.