Hi,
my old WEGA studio 3220 hifi console (see 1st picture) has a severe hum issue when I switch it for turntable operation. Unfortunately the manufacturer had arranged the power transformer beneath the TT's left and backmost corner (see 2nd picture). I have another one of later make that doesn't hum, but has a defunct FM section. This one had a shielding steel cover atop the tranny, so I decided to transfer the cover into the first console. My 2nd picture shows the console after this operation, the cover has a square hole. But this didn't cure anything. When I remove the TT (2nd pic), leaving it connected, and move it around, the hum changes it's sound. So it is clear to me that it results from magnetic stray from the tranny into the pickup. Changing the pickup doesn't alter anything either.
What's exactly the reason for it? Why is hum at one device only and none at the other identical device? What else can I do to cure it?
Best regards!
my old WEGA studio 3220 hifi console (see 1st picture) has a severe hum issue when I switch it for turntable operation. Unfortunately the manufacturer had arranged the power transformer beneath the TT's left and backmost corner (see 2nd picture). I have another one of later make that doesn't hum, but has a defunct FM section. This one had a shielding steel cover atop the tranny, so I decided to transfer the cover into the first console. My 2nd picture shows the console after this operation, the cover has a square hole. But this didn't cure anything. When I remove the TT (2nd pic), leaving it connected, and move it around, the hum changes it's sound. So it is clear to me that it results from magnetic stray from the tranny into the pickup. Changing the pickup doesn't alter anything either.
What's exactly the reason for it? Why is hum at one device only and none at the other identical device? What else can I do to cure it?
Best regards!
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I still don't have any clue why the unit with the now sielded power transformer develops a lot more of magnetic stray than the other one without the shielding. Maybe the reason is the increased mains voltage that might drive it's double C core into saturation. But hey, the other transformer that doesn't stray was manufactured in 1971 also, when we had a mains voltage of 220 Vac instedad of 230 Vac. Maybe the transformer itself is defective. 😕
Although really being no expert in RF stuff, I decided to give it a try and to fix the silent unit's defunct FM radio section. And, yessss, I eventually managed it 😛! I found out that there was no tuning voltage present at the front end's varactors. The reason for this simply was a broken wire at the power transformer's solder lugs. Fortunately not a real RF issue. I resoldered the wire and my good old Wega (the younger and silent one) is fully functional again!
Best regards!
Although really being no expert in RF stuff, I decided to give it a try and to fix the silent unit's defunct FM radio section. And, yessss, I eventually managed it 😛! I found out that there was no tuning voltage present at the front end's varactors. The reason for this simply was a broken wire at the power transformer's solder lugs. Fortunately not a real RF issue. I resoldered the wire and my good old Wega (the younger and silent one) is fully functional again!
Best regards!
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