Bush VHF70. - UK Vintage Radio Repair and Restoration Discussion Forum

ThePillenwerfer · 10th Feb 2012, 10:11 pm

I recently got this off e-Bay for 99p. I bought it chiefly because I felt sorry for it and thought that if I didn't give it a home it may get chucked. I was also perversely attracted by a sticker on it saying "VHF NBG."

The case was cracked along one side and the bottom. The side stuck with epoxy but the bottom repair kept breaking again so I reverted to my old technique of sticking the edges with super-glue and then reinforcing the inside with glue-gun glue, like applying a weld. So far that's holding and should be cool enough being at the bottom.

On the chassis front I changed THAT cap, snipped the filter and stuck some juice up it. It only worked on MW and a new UCC85 made no odds. I tested both the original and replacement valves in my VHF90 and the both worked so I needed to look elsewhere.

A routine re-cap sorted out LW but there was still nothing on VHF.

The insides were in very good condition and the wave switch looked as good as new, the contacts weren't even tarnished never mind damaged. Going 'round with my continuity tester revealed that everything was making and breaking as it should.

In the VHF box I found a 100kΩ resistor which was up to 115kΩ and as it was a ten per cent one I changed that but it made no odds. There was a 1μF electrolytic cap with an ESR of 7Ω but putting a 0.1μF across it didn't help.

I tried the signal injecting method but just managed to blow two 555s up without learning anything of use.

I eventually stuck an aerial on with the idea of seeing if poking about with a toothbrush handle would make any odds and the blooming thing started playing very nicely! This is all very well but as I don't know what cured it I don't know how long it'll work for.

I hadn't got any proper lamps so put LEDs in and also fitted a new Rifa filter cap which immediately caught fire and took the LEDs with it.

A new pair of LEDs behaved most oddly in that the left hand one was always brighter even if I swapped them. I went through all I'd got to find a 'Matched Pair' but the effect was the same and if I left it on the right-hand one would start flashing.

I therefore ordered some proper lamps, which look better, along with 1μF 400V caps.

The only problem I'd now got was not being able to find one of the knobs and MW disappearing after I put it back together. The knob eventually turned up; I had been worrying that it may have dropped into the gash bucket prior to emptying it on Monday night.

The bits came yesterday and the lamps are so far behaving. As expected, lack of MW was just because I'd pulled a wire off from the ferrite while re-assembling it

So that's another cubic foot or so of space gone and I got an Ultra Troubadour in my local auction earlier.

- Joe

ThePillenwerfer · 10th Feb 2012, 10:48 pm

Thanks to whoever corrected the thread title. I don't know what came over me.

- Joe

10th Feb 2012, 10:11 pm	#1
ThePillenwerfer Octode Join Date: Mar 2011 Location: Sheffield, South Yorkshire, UK. Posts: 1,453	Bush VHF70. I recently got this off e-Bay for 99p. I bought it chiefly because I felt sorry for it and thought that if I didn't give it a home it may get chucked. I was also perversely attracted by a sticker on it saying "VHF NBG." The case was cracked along one side and the bottom. The side stuck with epoxy but the bottom repair kept breaking again so I reverted to my old technique of sticking the edges with super-glue and then reinforcing the inside with glue-gun glue, like applying a weld. So far that's holding and should be cool enough being at the bottom. On the chassis front I changed THAT cap, snipped the filter and stuck some juice up it. It only worked on MW and a new UCC85 made no odds. I tested both the original and replacement valves in my VHF90 and the both worked so I needed to look elsewhere. A routine re-cap sorted out LW but there was still nothing on VHF. The insides were in very good condition and the wave switch looked as good as new, the contacts weren't even tarnished never mind damaged. Going 'round with my continuity tester revealed that everything was making and breaking as it should. In the VHF box I found a 100kΩ resistor which was up to 115kΩ and as it was a ten per cent one I changed that but it made no odds. There was a 1μF electrolytic cap with an ESR of 7Ω but putting a 0.1μF across it didn't help. I tried the signal injecting method but just managed to blow two 555s up without learning anything of use. I eventually stuck an aerial on with the idea of seeing if poking about with a toothbrush handle would make any odds and the blooming thing started playing very nicely! This is all very well but as I don't know what cured it I don't know how long it'll work for. I hadn't got any proper lamps so put LEDs in and also fitted a new Rifa filter cap which immediately caught fire and took the LEDs with it. A new pair of LEDs behaved most oddly in that the left hand one was always brighter even if I swapped them. I went through all I'd got to find a 'Matched Pair' but the effect was the same and if I left it on the right-hand one would start flashing. I therefore ordered some proper lamps, which look better, along with 1μF 400V caps. The only problem I'd now got was not being able to find one of the knobs and MW disappearing after I put it back together. The knob eventually turned up; I had been worrying that it may have dropped into the gash bucket prior to emptying it on Monday night. The bits came yesterday and the lamps are so far behaving. As expected, lack of MW was just because I'd pulled a wire off from the ferrite while re-assembling it So that's another cubic foot or so of space gone and I got an Ultra Troubadour in my local auction earlier. - Joe Attached Thumbnails __________________ "Experts are only good at one thing: explaining why something will not work!"

10th Feb 2012, 10:48 pm	#2
ThePillenwerfer Octode Join Date: Mar 2011 Location: Sheffield, South Yorkshire, UK. Posts: 1,453	Re: Bush VHF70. Thanks to whoever corrected the thread title. I don't know what came over me. - Joe __________________ "Experts are only good at one thing: explaining why something will not work!"