Hi all...Maybe some one has had this happen to them with other tube peaces Amps Preamps...what ever....
I pick up a Dyna Pas3X an a Dyna FM3....got home To ck out all with my Varcik...Pass sounds sweet....pull the cover of the FM3 tuner.. tune it on...Sweet tone...all stock not one Mod..all Dynaco tubes...even the two 12AX7 Telefunken tubes...that I have read ...guys pull out....pulls in FM Radio Stations right off..NPR jazz....work great cap ck out good No nose...No hum.
So then I got ready to put the bottem plat back on...but when I got ready to put the Top cover back on....AS soon as I got the cover close to the transfourmer...Got this HUM..vibration,you can fell...not hum in the sound...seemed to make no diff to the sound....but buzzing you can hear & feel...pull the top back...Dead Quiet...Anyone seen this?...How can I stop this?
Only thing I was thinking was...the heater & B+ wiring come off the transfourmer..one needs to be reverse...? not sure..
Thanks for any an all info on getting better sound out of tube Audio equipment.
I pick up a Dyna Pas3X an a Dyna FM3....got home To ck out all with my Varcik...Pass sounds sweet....pull the cover of the FM3 tuner.. tune it on...Sweet tone...all stock not one Mod..all Dynaco tubes...even the two 12AX7 Telefunken tubes...that I have read ...guys pull out....pulls in FM Radio Stations right off..NPR jazz....work great cap ck out good No nose...No hum.
So then I got ready to put the bottem plat back on...but when I got ready to put the Top cover back on....AS soon as I got the cover close to the transfourmer...Got this HUM..vibration,you can fell...not hum in the sound...seemed to make no diff to the sound....but buzzing you can hear & feel...pull the top back...Dead Quiet...Anyone seen this?...How can I stop this?
Only thing I was thinking was...the heater & B+ wiring come off the transfourmer..one needs to be reverse...? not sure..
Thanks for any an all info on getting better sound out of tube Audio equipment.
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Hi,
I guess the top cover is steel of some sort. The transformer will have a magnetic field round it that changes sign (North / South) at your mains frequency 60 cycles. What you feel is the cover being pulled to then repelled from the core of the transformer at 60 cycles.
Changing the 'polarity' (reversing) of the transformer wires will have no effect as it works with Alternating Current (AC) so is changing polarity (at 60 cycles again) already.
As the unit is 'un-touched' the obvious place to start is to check it is not drawing too much current and making the magnetic field round the transformer larger than it should be.
A faulty reservoir / smoothing capacitor C32 a,b,c and d is a prime suspect. Switch off and remove the EZ80/6V4. Now switch back on and try the cover again. If the buzz is reduced / gone, refit the rectifier and check the voltage on pin 3. According to the circuit diagram you should have 285 volts DC there so 270 to 280 volts is OK. Any less indicates a poor EZ80 or extra current is being drawn. (The voltages on the individual sections of C32 are a 285, b 255, c 225 and d 220 volts.)
If the buzz remains the same then a mechanical solution will be needed, such as tightening the mounting hardware and or fitting rubber, foam or felt pads to absorb the movement.
Always fancied trying one, but they are not common in the UK. Alan
I guess the top cover is steel of some sort. The transformer will have a magnetic field round it that changes sign (North / South) at your mains frequency 60 cycles. What you feel is the cover being pulled to then repelled from the core of the transformer at 60 cycles.
Changing the 'polarity' (reversing) of the transformer wires will have no effect as it works with Alternating Current (AC) so is changing polarity (at 60 cycles again) already.
As the unit is 'un-touched' the obvious place to start is to check it is not drawing too much current and making the magnetic field round the transformer larger than it should be.
A faulty reservoir / smoothing capacitor C32 a,b,c and d is a prime suspect. Switch off and remove the EZ80/6V4. Now switch back on and try the cover again. If the buzz is reduced / gone, refit the rectifier and check the voltage on pin 3. According to the circuit diagram you should have 285 volts DC there so 270 to 280 volts is OK. Any less indicates a poor EZ80 or extra current is being drawn. (The voltages on the individual sections of C32 are a 285, b 255, c 225 and d 220 volts.)
If the buzz remains the same then a mechanical solution will be needed, such as tightening the mounting hardware and or fitting rubber, foam or felt pads to absorb the movement.
Always fancied trying one, but they are not common in the UK. Alan
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Well as you have found C32 has to be replaced.
Rules for old elco capacitors,
Cool = might be ok, but probably low uF or just open circuit.
Warm = might re-form, but unlikely.
Hot = danger of going pop any time and taking the rectifier and transformer too.
Hot and fizzing = Switch Off and stand well clear till it cools. Likely to shower you with its contents any second! And there is a lot in there!
Rules for old elco capacitors,
Cool = might be ok, but probably low uF or just open circuit.
Warm = might re-form, but unlikely.
Hot = danger of going pop any time and taking the rectifier and transformer too.
Hot and fizzing = Switch Off and stand well clear till it cools. Likely to shower you with its contents any second! And there is a lot in there!
> AS soon as I got the cover close to the transfourmer...Got this HUM..vibration,you can fell...
I believe this is normal.
(And you have sensitive fingers.)
(And you never had an "accident" holding metal parts above a Live Circuit.)
ALL soft steel vibrates in AC fields.
Screw it down, it won't vibrate enough to matter.
I believe this is normal.
(And you have sensitive fingers.)
(And you never had an "accident" holding metal parts above a Live Circuit.)
ALL soft steel vibrates in AC fields.
Screw it down, it won't vibrate enough to matter.
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