BUSH VHF70
I 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."
I 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. With this being at the bottom it won’t get hot enough to melt.
On the chassis front I changed the AF coupling cap, snipped the filter (I'd learnt from my experience with the VHF90) 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 they 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 didn’t help. There was a 1µF electrolytic cap with an ESR of 7Ω but putting a 0.1µF across it didn't make any difference.
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 was all very well but as I don't know what cured it I didn't know how long it'd work for.
I hadn't got any proper lamps so put LEDs in and also fitted a new Rifa filter cap — I didn't know their reputation at the time — 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 along with 1µF 400V X-type caps and when these were fitted all was well.
The radio worked for a while but then VHF started vanishing after being on for a few minutes. I eventually found that there was a loose connection in the aerial plug.
On the chassis front I changed the AF coupling cap, snipped the filter (I'd learnt from my experience with the VHF90) 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 they 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 didn’t help. There was a 1µF electrolytic cap with an ESR of 7Ω but putting a 0.1µF across it didn't make any difference.
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 was all very well but as I don't know what cured it I didn't know how long it'd work for.
I hadn't got any proper lamps so put LEDs in and also fitted a new Rifa filter cap — I didn't know their reputation at the time — 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 along with 1µF 400V X-type caps and when these were fitted all was well.
The radio worked for a while but then VHF started vanishing after being on for a few minutes. I eventually found that there was a loose connection in the aerial plug.