Puzzling Tandberg hum cured! - UK Vintage Radio Repair and Restoration Discussion Forum

Tractorfan · 26th Sep 2012, 8:42 pm

Hi,
It's not often I post here as I don't usually have that much success with anything without valves in it! However, I feel I have to tell you about a successful repair that I notched up this afternoon.
I bought a Tandberg Series 15 open reel tape recorder a couple of months ago for 4 euros. Apart from a bit of damage to the teak style case, it looked in good order and worked well.
After a while I noticed that there was a hum that came & went at odd times. It disappeared when the volume was turned down so I assumed that the smoothing circuit was OK.
It was raining today so I decided to have a look at it and removed the chassis from its case. Sitting flat on the bench the hum was present, tipping the chassis up onto its rear side, the hum stopped. Putting back down made the hum reappear again. Hm? I spent a while checking the inter-chassis plugs and cleaning switches, etc. It turns out that it was a capacitor. The soldered joint between the cap & the printed circuit had fractured and was intermittent. It was the larger cap on the power amp board, it must smooth the circuitry before the volume control as I could turn the hum down to nearly zero. Also, the hum would be recorded onto the tape even with the gain controls at zero.
After resoldering the joint it is now nice & quiet. I think it must have been dropped at some time in the past, then disposed of because of the hum, perhaps.
Cheers, Pete

vinrads · 26th Sep 2012, 10:09 pm

Well done Pete ,a very nice tape recorder well worth saving. Mick.

ben · 27th Sep 2012, 12:56 am

As a long term tandberg fan (owning ten of them!) , I say well done. Remember, with a new belt, these machines simply fly.

26th Sep 2012, 8:42 pm	#1
Tractorfan Dekatron Join Date: Mar 2008 Location: St. Frajou, l'Isle en Dodon, Haute Garonne, France.(Previously: Ellesmere Port, Cheshire, UK.) Posts: 3,184	Puzzling Tandberg hum cured! Hi, It's not often I post here as I don't usually have that much success with anything without valves in it! However, I feel I have to tell you about a successful repair that I notched up this afternoon. I bought a Tandberg Series 15 open reel tape recorder a couple of months ago for 4 euros. Apart from a bit of damage to the teak style case, it looked in good order and worked well. After a while I noticed that there was a hum that came & went at odd times. It disappeared when the volume was turned down so I assumed that the smoothing circuit was OK. It was raining today so I decided to have a look at it and removed the chassis from its case. Sitting flat on the bench the hum was present, tipping the chassis up onto its rear side, the hum stopped. Putting back down made the hum reappear again. Hm? I spent a while checking the inter-chassis plugs and cleaning switches, etc. It turns out that it was a capacitor. The soldered joint between the cap & the printed circuit had fractured and was intermittent. It was the larger cap on the power amp board, it must smooth the circuitry before the volume control as I could turn the hum down to nearly zero. Also, the hum would be recorded onto the tape even with the gain controls at zero. After resoldering the joint it is now nice & quiet. I think it must have been dropped at some time in the past, then disposed of because of the hum, perhaps. Cheers, Pete __________________ "Hello?, Yes, I'm on the train, I might lose the signal soon as we're just going into a tunn..."

26th Sep 2012, 10:09 pm	#2
vinrads Dekatron Join Date: Feb 2009 Location: Chesterfield, Derbyshire, UK. Posts: 3,763	Re: Puzzling Tandberg hum cured! Well done Pete ,a very nice tape recorder well worth saving. Mick.

27th Sep 2012, 12:56 am	#3
ben Dekatron Join Date: Aug 2006 Location: Madrid, Spain / Wirral, UK Posts: 7,498	Re: Puzzling Tandberg hum cured! As a long term tandberg fan (owning ten of them!) , I say well done. Remember, with a new belt, these machines simply fly. __________________ Regards, Ben.