Power takes time to turn off.

[nomrah]

The problem I am having is that after I installed new binding posts for my speaker cables on my power amp when the power switch is turned off it takes at least 10 seconds for the power to shut down. I also changed the two snubbers one on each channel and was careful to use the same values on the caps and the resistors. Can someone speculate about this problem.

 

[Watthour]

What unit?

 

[quiet]

I didn't know that was a problem. I have one 70s receiver that plays very well for about fifteen seconds after shut down. I don't remember which one.

 

[Goldie99]

I didn't know that was a problem....

It probably isn't, but it does depend on the unit concerned, e.g., does it have a protection relay, muting circuits, etc. For some older units it's perfectly normal, for others it would indicate a problem.

 

[bimasta]

I had a few amps like that. It was explained to me that the big power-supply caps continue to discharge even after switching off.

 

[nomrah]

The power amp is a Superphon DM220. Before I changed the snubbers and binding posts the power shut off immediately when the switch was shut off. I do not think there is a relay in the unit and there are no muting circuits. Each of the power caps also have snubbers on them which I also newly installed. I saved the old snubbers on the power caps and can install the old ones to see if this makes a difference. I do not think it would.

 

[savatage1973]

If the amp has no speaker relays/muting circuit, what you are likely hearing/seeing is the slow discharge of the main PS caps. The old snubbers may have been shorted and allowed for immediate discharge, which equals immediate shut-off. If the discharge is slowed, the amp will be slow to power down.

 

[whoaru99]

The power amp is a Superphon DM220. Before I changed the snubbers and binding posts the power shut off immediately when the switch was shut off. I do not think there is a relay in the unit and there are no muting circuits. Each of the power caps also have snubbers on them which I also newly installed. I saved the old snubbers on the power caps and can install the old ones to see if this makes a difference. I do not think it would.

If there is no relay or no muting circuit then it would seem unlikely the unit would have stopped playing immediately.

What, specifically, do you mean by "snubbers"? I know some uses of that term but want to be on the same page for sure.

Value of original vs value of replacement?

 

[nomrah]

The snubbers are one capacitor and one resistor in series between the terminals on the power caps and the terminals on each channel for the binding posts. I was careful to have same values on the new caps and resistors to match the old caps and resistors. I was also careful that the binding posts did not touch the sides of the newly drilled holes they were inserted in to avoid any grounding or short.

 

[quiet]

The snubbers are one capacitor and one resistor in series between the terminals on the power caps and the terminals on each channel for the binding posts. I was careful to have same values on the new caps and resistors to match the old caps and resistors. I was also careful that the binding posts did not touch the sides of the newly drilled holes they were inserted in to avoid any grounding or short.

Now I see your desire to know just what's going on.

 

[whoaru99]

The snubbers are one capacitor and one resistor in series between the terminals on the power caps and the terminals on each channel for the binding posts. I was careful to have same values on the new caps and resistors to match the old caps and resistors. I was also careful that the binding posts did not touch the sides of the newly drilled holes they were inserted in to avoid any grounding or short.

Then my opinion it has always been that way but for some reason not previously noted.

 

[Djcoolray]

Easy fix...

Leave it on, the heating up and cooling down of the circuits is detrimental to the effectiveness of the circuits to produce consistent quality sound. The metal within the internal components becomes brittle degrading sound quality and that’s why internal components suffer S/N ratio loss over time. It’s not like a unit only has so many hours of use before replacing....

 

[Goldie99]

Are the 'snubbers' not part of Zobel ?

 

[quiet]

Easy fix...

Leave it on, the heating up and cooling down of the circuits is detrimental to the effectiveness of the circuits to produce consistent quality sound. The metal within the internal components becomes brittle degrading sound quality and that’s why internal components suffer S/N ratio loss over time. It’s not like a unit only has so many hours of use before replacing....

I often wondered about that. Many different opinions maybe.

 

[Djcoolray]

I often wondered about that. Many different opinions maybe.

Facts are facts, if a person reads about metallurgy and the process of creating alloyed metals they learn what is detrimental to the integrity of the alloyed metals. If a person doesn’t read they are stuck with collective opinions which creates fallacies passed on to others as facts. Then those that have the facts are looked upon as confused due to the lack of conformity.

 

[markn2wae]

Why where the "snubber s" as you called them replaced?

If it was for "darkend" resistors , you MAY have read the color bands wrong and installed the wrong parts?

Are you playing with "bleeder" resistors that connect to the capacitors?

A changed value and/or not being reconnected properly may cause the capacitors to "stay charged longer than they normally would, producing "music playing" for a longer period on switch off.

Mark T.

 

[nomrah]

The amp is about twenty years old and I thought it would be a good idea to change all of the snubbers to new ones. Also replaced caps on audio boards. I will consider installing the old snubbers and see what happens. Thanks guys.

 

[whoaru99]

So it's not just the snubbers. Caps on some boards too.

What else?

 

[nomrah]

That's it. No other installs. There were only four caps on each board replaced.

 

[dshoaf]

Got a schematic of this amp? If so, post it and tell us what caps got replaced by their reference number. I'm not clear the arm chair bench techs here have all the info they need just yet.

Cheers,

David