Bush DAC70 restored. - UK Vintage Radio Repair and Restoration Discussion Forum

mark pirate · 20th Dec 2011, 10:08 pm

I picked up this little set for £2 back in the summer, I was told it was a loft find left by previous owners.

The DAC70 was introduced in June 1958, using the same cabinet as the VHF90A and as the replacement for the DAC90A. The DAC90A was sold alongside until its final demise in late 1959.
This particular set has Jan 59 on the smoothing cap.

I did power it up when I got it and it was sort of working, but very quiet. As I had better things to do, it was stuck in the loft until today.

When I took the back off I could see that someone had fitted one of those round RS dropper repair sections. I also noticed the rectifier valve looked quite new, the mains filter cap had spewed its wax and the 15 watt dial bulb was absent.

I removed the volume and wavechange knobs from the sides, then removed the chassis screws. By using gentle pressure I pulled the chassis forward, thus pulling the tuning dial of its shaft without damage.

There were no signs of repair behind the chassis, just a handful of Hunts Mouldseals to deal with. I removed the large aluminium light tray to get better access to the chassis, then set about replacing the capacitors.

With the underside now recapped, I cleaned and refitted the light tray. Time for the topside; there are only three caps to replace here, two of which are mounted on the output transformer.

I now powered up the set and was greeted by music. There was now plenty of volume and plenty of stations on both bands.

I then cleaned the chassis, valves, valve pins and applied a squirt of Servisol to the valveholders, volume pot and wavechange switch. I then remembered that I had the correct pygmy bulb for the dial light; I fitted this, then made a start on the cabinet.

Actually, this was reasonably clean anyway so not much effort was needed here. It was a bit mucky on the inside and the back of the dial but this wiped away with a bit of washing up liquid and a cloth.

I gave it a polish with T-Cut, followed by neutral wax. The knobs were cleaned and the set was reassembled.

I am quite lucky with this set, the dial lamp can burn the rear of the dial if not fitted correctly but the dial on this set is perfect, so I was very careful to make sure I fitted it properly!

The set now works very well. The sound quality is quite good but this set is not as good as the DAC90A in both build and sound quality, but that's progress for you

Another problem area on these sets is that the gold plastic trim round the speaker cloth shrinks and hardens. Sadly my set is no exception to this and it really spoils the appearance. I will keep an eye out for something similar to replace it. I also need to find the brass trim for the centre of the tuning dial, I am sure it was there when I got the set.

The best use for this set would be a bedside radio, you could lie in bed using the radio's dial as a reading lamp!

Does anyone remember the Terry's 'Moonlight' TV advert featuring this set?

Mark

mark pirate · 20th Dec 2011, 10:11 pm

And the finished result...

Lloyd 1985 · 20th Dec 2011, 10:26 pm

Hi,
Another fantastic result!
Would gentle heating from a hairdryer then stretching the plastic trim back into place/ shape work? I'll give it a shot one of mine, I've got 2, but I'm sure the best one has a metal trim, Not sure if it's original or not!

Regards,
Lloyd.

Wellington · 20th Dec 2011, 10:40 pm

Good Job, Mark. The more I see these sets, the more I like 'em.

On a cautionary note, I thought I read somewhere on this forum that even when fitted correctly, the dial light can generate damaging amounts of heat. I have the impression that other repairers have reduced the power to save their dials. Yes - it was mentioned here.

Regarding the gold plastic trim, I wonder if the plastic beading used around the edges of a sports bag would be a suitable replacement?

Nice photo with the dial illuminated - starting to want a DAC70....

paulsherwin · 20th Dec 2011, 10:55 pm

No, the original bulb will be fine if it's positioned correctly. It's easy to get this wrong when changing the bulb.

Modern smaller bulbs do give a bigger safety margin though.

pepmin 1 · 21st Dec 2011, 3:47 am

Hi. I have a Bush Dac70, and a Bush VHF90A. The VHF90A dial suffers slightly from heat damage so I did not want to put the 15w pigmy bulb back in. I managed to source two 7W SBC bulbs from here. http://www.lamps2udirect.com/pages/f...ght-bulb/70228 They were not cheap , £8 for me with delivery and v.a.t. But they fit perfectly and do not generate much heat. They light up the dials great as well. Colin.

PJL · 21st Dec 2011, 10:03 am

The gold trim is a low melting point thermoplastic. Get a hair dryer on it and you will find it very quickly become malleable and can be put back into shape. You just need to be quick as it cools and hardens again very quickly!

telstar · 21st Dec 2011, 11:32 am

Hi. I have one of these Bush DAC70 radios in my collection. They are quite easy to restore, and I have definately replaced all the Hunts "Mouldseal" capacitors, as they were showing signs of deteriorating. The oscillator anode capacitor was the first one that I found to be faulty, as replacing it brought the set back to life.
From what I remember, the manufacturer's service data had an error on it around the output transformer area?
Regards
Mike

gavinhall · 21st Dec 2011, 9:55 pm

I've just done one of these and I use it in the bedroom to go to sleep to. It's on a time switch and looks lovely, I just stare at the dial and nod off to Gold on MW.

20th Dec 2011, 10:08 pm	#1
mark pirate Dekatron Join Date: Mar 2008 Location: Worthing, West Sussex, UK Posts: 5,185	Bush DAC70 restored. I picked up this little set for £2 back in the summer, I was told it was a loft find left by previous owners. The DAC70 was introduced in June 1958, using the same cabinet as the VHF90A and as the replacement for the DAC90A. The DAC90A was sold alongside until its final demise in late 1959. This particular set has Jan 59 on the smoothing cap. I did power it up when I got it and it was sort of working, but very quiet. As I had better things to do, it was stuck in the loft until today. When I took the back off I could see that someone had fitted one of those round RS dropper repair sections. I also noticed the rectifier valve looked quite new, the mains filter cap had spewed its wax and the 15 watt dial bulb was absent. I removed the volume and wavechange knobs from the sides, then removed the chassis screws. By using gentle pressure I pulled the chassis forward, thus pulling the tuning dial of its shaft without damage. There were no signs of repair behind the chassis, just a handful of Hunts Mouldseals to deal with. I removed the large aluminium light tray to get better access to the chassis, then set about replacing the capacitors. With the underside now recapped, I cleaned and refitted the light tray. Time for the topside; there are only three caps to replace here, two of which are mounted on the output transformer. I now powered up the set and was greeted by music. There was now plenty of volume and plenty of stations on both bands. I then cleaned the chassis, valves, valve pins and applied a squirt of Servisol to the valveholders, volume pot and wavechange switch. I then remembered that I had the correct pygmy bulb for the dial light; I fitted this, then made a start on the cabinet. Actually, this was reasonably clean anyway so not much effort was needed here. It was a bit mucky on the inside and the back of the dial but this wiped away with a bit of washing up liquid and a cloth. I gave it a polish with T-Cut, followed by neutral wax. The knobs were cleaned and the set was reassembled. I am quite lucky with this set, the dial lamp can burn the rear of the dial if not fitted correctly but the dial on this set is perfect, so I was very careful to make sure I fitted it properly! The set now works very well. The sound quality is quite good but this set is not as good as the DAC90A in both build and sound quality, but that's progress for you Another problem area on these sets is that the gold plastic trim round the speaker cloth shrinks and hardens. Sadly my set is no exception to this and it really spoils the appearance. I will keep an eye out for something similar to replace it. I also need to find the brass trim for the centre of the tuning dial, I am sure it was there when I got the set. The best use for this set would be a bedside radio, you could lie in bed using the radio's dial as a reading lamp! Does anyone remember the Terry's 'Moonlight' TV advert featuring this set? Mark Attached Thumbnails

20th Dec 2011, 10:11 pm	#2
mark pirate Dekatron Join Date: Mar 2008 Location: Worthing, West Sussex, UK Posts: 5,185	Re: Bush Dac 70 Restored And the finished result... Attached Thumbnails Last edited by Mike Phelan; 21st Dec 2011 at 10:23 am. Reason: Unfished.

20th Dec 2011, 10:26 pm	#3
Lloyd 1985 Nonode Join Date: Jun 2008 Location: Coningsby, Lincolnshire, UK. Posts: 2,819	Re: Bush Dac70 restored. Hi, Another fantastic result! Would gentle heating from a hairdryer then stretching the plastic trim back into place/ shape work? I'll give it a shot one of mine, I've got 2, but I'm sure the best one has a metal trim, Not sure if it's original or not! Regards, Lloyd.

20th Dec 2011, 10:40 pm	#4
Wellington Hexode Join Date: Jun 2009 Location: Cheshire, UK. Posts: 363	Re: Bush Dac 70 Restored Good Job, Mark. The more I see these sets, the more I like 'em. On a cautionary note, I thought I read somewhere on this forum that even when fitted correctly, the dial light can generate damaging amounts of heat. I have the impression that other repairers have reduced the power to save their dials. Yes - it was mentioned here. Regarding the gold plastic trim, I wonder if the plastic beading used around the edges of a sports bag would be a suitable replacement? Nice photo with the dial illuminated - starting to want a DAC70....

20th Dec 2011, 10:55 pm	#5
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,947	Re: Bush DAC70 restored. No, the original bulb will be fine if it's positioned correctly. It's easy to get this wrong when changing the bulb. Modern smaller bulbs do give a bigger safety margin though.

21st Dec 2011, 3:47 am	#6
pepmin 1 Pentode Join Date: Nov 2010 Location: Inverness, Scottish Highlands, UK. Posts: 226	Re: Bush DAC70 restored. Hi. I have a Bush Dac70, and a Bush VHF90A. The VHF90A dial suffers slightly from heat damage so I did not want to put the 15w pigmy bulb back in. I managed to source two 7W SBC bulbs from here. http://www.lamps2udirect.com/pages/f...ght-bulb/70228 They were not cheap , £8 for me with delivery and v.a.t. But they fit perfectly and do not generate much heat. They light up the dials great as well. Colin. Last edited by pepmin 1; 21st Dec 2011 at 3:58 am.

21st Dec 2011, 10:03 am	#7
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Bush DAC70 restored. The gold trim is a low melting point thermoplastic. Get a hair dryer on it and you will find it very quickly become malleable and can be put back into shape. You just need to be quick as it cools and hardens again very quickly!

21st Dec 2011, 11:32 am	#8
telstar Octode Join Date: Dec 2003 Location: Leeds, West Yorkshire, UK. Posts: 1,592	Re: Bush DAC70 restored. Hi. I have one of these Bush DAC70 radios in my collection. They are quite easy to restore, and I have definately replaced all the Hunts "Mouldseal" capacitors, as they were showing signs of deteriorating. The oscillator anode capacitor was the first one that I found to be faulty, as replacing it brought the set back to life. From what I remember, the manufacturer's service data had an error on it around the output transformer area? Regards Mike

21st Dec 2011, 9:55 pm	#9
gavinhall Retired Dormant Member Join Date: Sep 2007 Location: Maidstone, Kent, UK. Posts: 109	Re: Bush DAC70 restored. I've just done one of these and I use it in the bedroom to go to sleep to. It's on a time switch and looks lovely, I just stare at the dial and nod off to Gold on MW.