09-08-2012, 08:09 PM
I may have had a Eureka moment. Last night I spent hours with Photoshop starting to make a dial image from the various scans and photos - this will take a while.
Tonight I went back to the electronics and figured all the problems were around the 6Q7. I went back to the valves originally in the set and in this position was a 6H8. Having checked the pin-outs, these are similar but not the same so some wiring changes were made to accommodate the 6H8. When I put the 6H8 back in I get much more acceptable voltage readings though there is now a noticeable hum in the audio.
I think I'll see about modifying the wiring to accept the 6Q7 so the set more accurately reflects the only circuit diagram I've been able to find. I appreciate this set was produced in war time and they used whatever was available so this could have been done in the factory - I don't see any signs it was done afterwards.
I also started to systematically identify all the components under the chassis so I would have a ref and I've found some more anomalies which might be down to me being tired or there are other changes I need to investigate. For example in the diagram there are two caps with a value of 0.25uF - I can find only one in my set!
So, some light at the end of the tunnel - let's hope it's not a train coming
Cheers, John
Tonight I went back to the electronics and figured all the problems were around the 6Q7. I went back to the valves originally in the set and in this position was a 6H8. Having checked the pin-outs, these are similar but not the same so some wiring changes were made to accommodate the 6H8. When I put the 6H8 back in I get much more acceptable voltage readings though there is now a noticeable hum in the audio.
I think I'll see about modifying the wiring to accept the 6Q7 so the set more accurately reflects the only circuit diagram I've been able to find. I appreciate this set was produced in war time and they used whatever was available so this could have been done in the factory - I don't see any signs it was done afterwards.
I also started to systematically identify all the components under the chassis so I would have a ref and I've found some more anomalies which might be down to me being tired or there are other changes I need to investigate. For example in the diagram there are two caps with a value of 0.25uF - I can find only one in my set!
So, some light at the end of the tunnel - let's hope it's not a train coming
Cheers, John
Time flies like an arrow, fruitflies like a banana!
