06-12-2013, 10:49 AM
(This post was last modified: 06-12-2013, 10:58 AM by Robert Darwent.)
(03-12-2013, 04:05 PM)lol30 Wrote: i have replaced the capacitors c10/c22/c23/c25/c27 & has made a minute improvement but it still is very faint
Hi Laurie,
I see you have replaced several capacitors suggested by others with no real improvement, in that case your problem is likely to be with the detector diode.
In the Bush service sheets (found in post #17 of this thread) the diode is labelled CD1 and is housed inside the can of IFT3, which is found roughly in the middle of the chassis at the bottom edge. The service sheets have a couple of images showing its exact location.
(01-12-2013, 07:32 PM)Yorkie Wrote: it is by no means uncommon for the detector diode to fail (an OA70), which is hiding away inside the can of IFT3... ...more or less any germanium diode will suffice as a replacement - OA90/91 1N34 etc.
As David says above, replacement with an OA90/91 germanium diode is suitable. However, it is not necessary to fit it inside the IFT can, simply soldering it between pins 5 and 6 of IFT3 on the underside of the chassis is just as good.
To do that you will need to remove the chassis from the case which means taking the large clear tuning knob and pointer off first. My method of doing this can be found described in post #18 of the thread; http://golbornevintageradio.co.uk/forum/...p?tid=1558
After removing the knob and pointer you will need to take out the four chassis screws (one at each corner) and take the chassis out by lifting from the bottom edge first.
When refitting the knob and pointer, ensure the tuning capacitor is fully meshed and fit the pointer horizontally. Don't push it too far down the shaft, it needs to sit on the slightly larger diameter section at the bottom of the shaft but not too low it is scrapping against the dial.
Regards
