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Thorens TD 160 "pop" revisited

I realize that I may be late to this party, however I'm seeking some clarification and am hoping to get the final answer to this issue. 

Just finished setting up new (to me) system with a beautiful TD 160, Rega 300 tonearm and Pete Riggles VTAF modification, along with his counterweight system. Connected to a restored Accuphase E-202, sending to a pair of Klipsch Forte IV. 

To my ears, the sound is heavenly. 

But: when I switch on the tt, there is a LOUD POP. I've seen discussions regarding snubbers and various capacitors placed within the tt, and yet others have said that failed to solve issue. Another post said he finally find the solution was adding a resistor somewhere unspecified. 

Has anyone come up with a final reason why this happens and a proven solution? 

sailmed
jea48
4,493 posts
 

As a rule turn on, (closure of the ON/OFF switch contacts), does not cause a high voltage transient. Opening the switch contact, (creating an arc), causes the voltage transient.

To protect all the audio electronic equipment from the high voltage transient all equipment would have to be powered off. Not just the power amplifier.

 

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dekay's avatar
dekay
5,668 posts
 

Here's some discussion of eliminating the startup pop.

Having owned 5-6 TD160's I recall that the circuits can vary a bit (and I'm pretty certain that mine were all original/stock).

https://www.vinylengine.com/turntable_forum/viewtopic.php?t=76532

 

DeKay

jea48
4,493 posts
 

A resistor should be wired in series with the capacitor.

 

“Snubber” Circuit

A sudden rise in voltage across the switch contact caused by the contact opening will be tempered by the capacitor’s charging action (the capacitor opposing the increase in voltage by drawing current).

The resistor limits the amount of current that the capacitor will discharge through the contact when it closes again. If the resistor were not there, the capacitor might actually make the arcing during contact closure worse than the arcing during contact opening without a capacitor!

 

sailmed OP
43 posts
 

Thank you all for very helpful and thought provoking advice. I'm going to ensure there is a proper snubber circuit including a capacitor and a resistor across the switch. Apparently, if left uncorrected it will eventually fry the contacts.

After it's all done, I'll update with details for the benefit of the next poor soul.  😉

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