• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Valve Amplifier valve identification

eye looks mostly like what I'd expect, two 1M resistors. Not sure what the other is. That type resistor seems prone to going very far off value though, so it would be worth checking them. If they're too far out to lunch the eye may not work. The values aren't overly critical but the resistors can't be open.
 
fink lever said:
It seems the am pre and fm were taken from another unit and adapted to the amplifier...there are no makers identification but a Christmas Tree logo on the am facia.
Click to expand...
Quite likely, if not purchased as ready made modules.
The AM unit may have come from a radiogram, the FM unit looks a self-powered add-on, such as Telefunken FM-1C add-on used to provide FM coverage in my Telefunken Opus 49.
Have you more pix of the AM/ preamp?
 
gadget73 said:
eye looks mostly like what I'd expect, two 1M resistors. Not sure what the other is. That type resistor seems prone to going very far off value though, so it would be worth checking them. If they're too far out to lunch the eye may not work. The values aren't overly critical but the resistors can't be open.
Click to expand...
Ok I will see if I can test. I have ordered a spare em34 valve so will know more when it arrives
Pio1980 said:
Quite likely, if not purchased as ready made modules.
The AM unit may have come from a radiogram, the FM unit looks a self-powered add-on, such as Telefunken FM-1C add-on used to provide FM coverage in my Telefunken Opus 49.
Have you more pix of the AM/ preamp?
Click to expand...
I hope to remove the am pre over the weekend and will post some pics, underneath and at various angles. Maybe give it a clean and good study...
 
IMG_20180515_215947.jpeg IMG_20180515_220046.jpeg IMG_20180515_220101.jpeg IMG_20180515_220106.jpeg IMG_20180515_220120.jpeg IMG_20180515_220141.jpeg Hello from England, IMG_20180515_215937.jpegIMG_20180515_215947.jpegIMG_20180515_220046.jpegIMG_20180515_220051.jpegIMG_20180515_220101.jpegIMG_20180515_220106.jpegIMG_20180515_220111.jpegIMG_20180515_220120.jpegIMG_20180515_220126.jpegIMG_20180515_220141.jpeg

The valve am pre has been removed and i have taken quite a few pics for everyone to observe. At the moment the EM34 does not light and the radio has a constant hf crackle (not really loud but it is affecting the signal and speakers) There doesn't seem to be anything obviously broken but this AM Pre was also given to the Tech but cannot see anything worked on. I have also cleaned inside as it was quite dusty. I am trying to figure out the missing two valves which are in the centre of the unit (the tech said they are not important) but i beg to differ as by looking at the wiring they seem to be an integral part of the circuit. Following the wiring from the Magic eye in the corner there are a couple of resistors/capacitor that is covered in like a black glue type grime (pic 2) (not sure if this is normal) and think this may have something to do with the unit not sounding as it should. Please if anyone can spot something i can't i would love to know. At present i cannot check the unit properly as i have no multimeter.

I will also remove the speakers and continue to update with pics...The interference and crackle is more predominant with the smaller speaker so i may change this not knowing if the speaker is not functioning as well as it should.

There is also one knob (bottom right) that the Tech said is reduntant but as it is wired up as contrast control i am assuming something is not quite right somewhere.
 
Last edited:
I think I have very good news!
The trademark on the dial is Bush radio company. That means a websearch for circuit information should now be possible for this part of the set.
 
Pio1980 said:
I think I have very good news!
The trademark on the dial is Bush radio company. That means a websearch for circuit information should now be possible for this part of the set.
Click to expand...
Excellent observation Pio1980, really appreciate the news. Looks like i may be able to figure out the circuit.
 
Pio1980 said:
Home site;
https://www.vintage-radio.com/index.html

We are probably looking for a radiogram.
Click to expand...
Yes i have spotted a couple that look similar (one marconi 1940s and the other a 1950s bush radiogram with a similar faceplate. I think i will be able to continue the search Pio thanks again.

By the way i have just removed the speaker and i must say i should have done earlier as they are soooo dusty but in lovely condition. Interestingly the smaller WB speaker had a wooden block cone that had come loose from the speaker and was rattling in the cover. I thought it was a wizzer cone that had come loose but it is solid wood (never seen one before) so this may have been causing some issue. Plus i have just removed the large goodmans and again the wire from inside was not a bulb as i guessed but a german electrostatic tweeter that i have never also seen before. Very unusual. This for me now solves one riddle with a connector that i did not know what it was. I still cannot tell if it works yet so i have cleaned it. Trying to upload pics but i may be on my max as its not happening....
 
Marconi and EMI had an arrangement on Television receivers in the mid/late 1930s. Is it possible that Bush and Marconi had something similar here?
 
fink lever said:
Yes i have spotted a couple that look similar (one marconi 1940s and the other a 1950s bush radiogram with a similar faceplate. I think i will be able to continue the search Pio thanks again.

By the way i have just removed the speaker and i must say i should have done earlier as they are soooo dusty but in lovely condition. Interestingly the smaller WB speaker had a wooden block cone that had come loose from the speaker and was rattling in the cover. I thought it was a wizzer cone that had come loose but it is solid wood (never seen one before) so this may have been causing some issue. Plus i have just removed the large goodmans and again the wire from inside was not a bulb as i guessed but a german electrostatic tweeter that i have never also seen before. Very unusual. This for me now solves one riddle with a connector that i did not know what it was. I still cannot tell if it works yet so i have cleaned it. Trying to upload pics but i may be on my max as its not happening....
Click to expand...
Pio, i just had a realisation though regarding the AM pre.... the dials and controls must have been taken from an old radiogram but the chassis is the same as the amplifier so i think the maker has also built the AM Pre to suit. It makes sense as the wiring and setup is again too complex for a standard radio. Plus from what the Tech said is that the maker incorporated hi and low pass filters on the AM Pre enable each individual speakers tone to be controlled and then managed by a master volume. So even if i find the radiogram dial etc the circuits will probably be totally different. Anyhow i have gathered more info and it has been worthwhile as i am cleaning and learning at the same time. It is also my Birthday in 5mins so i have been treated to some peace and quiet from my family. I will have now a lovely hot cup of tea and then start to reattach everything and hope i do not have any screws left.
 
Hello All, i found an EF37 in my other small amplifier and though what the heck, lets put in the missing valve holder coupled with a power valve. I thought if anything seemed wrong i would quickly turn it all off. Low and behold nothing whent pot and when i turned the dial to AM and turned the contrast knob ( the one i was told was not connected!) it actually worked. Giving a holographic bassier sound when fully turned. I also acquired a magic eye which now works a charm! So i have managed somehow with luck to find the missing valves and sort the magic eye.

My final issue is know a 100hz hum coming from the large speaker and a hf 1000hz hum coming from the smaller. Took all the pre valves out buy made no diff. Took out the final valve in my amp (buy don't know what valve it is) and the hum reduced significantly but not totally. It looks like it powers the voltage stablilsers as they do no light when removed. Also the aerial sockets from the pre (grey and black/small and large speaker) could be the culprits) as when removed the hum also significantly falls.

Any ideas how i can remove this hum from the aerial inputs to the main amp?
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom