11-07-2012, 05:00 PM
I had a look at my newly-acquired R200 today.
The first problem was the volume pot being rusted solid. This soon freed up with a blast of Servisol.
The set didn't work but there was enough crackling to show that the output stage was working.
I tried tapping the AF117s and found that when I did the third one there was a noise from the speaker so I accused it of needing a shave and whipped it out. Testing found no shorts however so a bit of logical thought was called for.
A signal injected into its base came out of the speaker but not one applied to the base of Tr2 so that came out next.
This had shorts on all leads and didn't respond to bopping so I put a BC327 in.
When I reconnected the power I nearly got deafened as it happened to be on a station.
I thought that there were a few crackles when adjusting the tuning so disconnected the gang to test for shorts but didn't find any.
I hadn't so far tried LW and when I did found it was severely motor-boating. MW seemed to have gone off a lot too so I assumed that powering it up had pushed an ailing capacitor over the edge. This set is fitted with Grey Dubliners, which I'd no previous experience of, and any I tested seemed fine.
I was loathe to just change the lot and wondered if the wrong transistor was unhappy at the lower frequencies. I tried a few alternatives which made no real difference. These included a borrowed AF116.
I then got interrupted by my neighbour calling and when I resumed work I had a clear head.
The only thing I could think was that I'd disturbed something. I compared it to the chassis I'd borrowed the AF116 from and found I'd reconnected the tuning gang wrong.
After correcting this all was well on Medium Wave but not Long which was now just dead. This was traced to a break in the aerial coil which I managed to fix.
I then put the BC327 back and it was better than with the AF116. It was only at this point that the PCB decided to fall to bits so I'm glad that that can now be left alone.
I'm now left with the cosmetic stuff but won't be able to finish it until I can get the the upholstery shop for some green leather to mend the handle with.
A simple job ended up taking all afternoon but it's all good experience. You certainly learn more from your mistakes than when you do things right.
- Joe
The first problem was the volume pot being rusted solid. This soon freed up with a blast of Servisol.
The set didn't work but there was enough crackling to show that the output stage was working.
I tried tapping the AF117s and found that when I did the third one there was a noise from the speaker so I accused it of needing a shave and whipped it out. Testing found no shorts however so a bit of logical thought was called for.
A signal injected into its base came out of the speaker but not one applied to the base of Tr2 so that came out next.
This had shorts on all leads and didn't respond to bopping so I put a BC327 in.
When I reconnected the power I nearly got deafened as it happened to be on a station.
I thought that there were a few crackles when adjusting the tuning so disconnected the gang to test for shorts but didn't find any.
I hadn't so far tried LW and when I did found it was severely motor-boating. MW seemed to have gone off a lot too so I assumed that powering it up had pushed an ailing capacitor over the edge. This set is fitted with Grey Dubliners, which I'd no previous experience of, and any I tested seemed fine.
I was loathe to just change the lot and wondered if the wrong transistor was unhappy at the lower frequencies. I tried a few alternatives which made no real difference. These included a borrowed AF116.
I then got interrupted by my neighbour calling and when I resumed work I had a clear head.
The only thing I could think was that I'd disturbed something. I compared it to the chassis I'd borrowed the AF116 from and found I'd reconnected the tuning gang wrong.
After correcting this all was well on Medium Wave but not Long which was now just dead. This was traced to a break in the aerial coil which I managed to fix.
I then put the BC327 back and it was better than with the AF116. It was only at this point that the PCB decided to fall to bits so I'm glad that that can now be left alone.
I'm now left with the cosmetic stuff but won't be able to finish it until I can get the the upholstery shop for some green leather to mend the handle with.
A simple job ended up taking all afternoon but it's all good experience. You certainly learn more from your mistakes than when you do things right.
- Joe
