Author Topic: Amplifier pop  (Read 909 times)

Offline Aqualung

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Amplifier pop
« on: January 22, 2018, 05:02:16 PM »
Dear Vintage Fundis,

I have a Sony TA-1055 amp (looks good and sounds great) that, when I switch it on, makes a loud "click" on the speakers, and when I switch it off, a very loud "pop" sound on the speakers.

This happens even with volume set to zero.

I have done some reading, and have measured the DC mV at the speaker terminals with volume at zero and AUX selected as source:
L = 12mV DC and R=14mV DC.

This was on the "B" speaker terminals, as my speakers were connected to the "A" terminals.

I have also fitted a 270V 0.47uF "spark suppression" capacitor across the 239V AC Live and Neutral cables coming from the the mains where they connect to the On/Off switch - this made no difference? Do I leave it, or remove it?

Any idea why this is happening, and advice on how to sort this out?

Thanks,
Johan
 

I love music - analog and digital. Even listening to the Blues makes me happy. During the day I coach and counsel, after hours I indulge in my second passion - listening to vinyl and restoring turntables. Some I keep, some I sell...

Offline marantz123

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Re: Amplifier pop
« Reply #1 on: January 23, 2018, 12:20:13 AM »
Aqua

As long as the supression cap is across the switch contacts, it would be in the right place. The cap value chosen, unless a typo, is 470nF which is somewhat large. A 22nF to 47nF would be more suitable. ( the Marantz 1060 has  33nF cap for example) A cap of your size may allow sufficient current across it to keep the amp lamps on (dim) even when the amp is switched off but still connected to live mains.  If this amp has never been serviced, I suggest cleaning all the switches and pots first. Be careful with the power switch..if its one of those rotary red bakelite types then clean/flush it with Q20 and leave it to drain for a day on a warm window sill n then blow it out. Q20 leaves a light film which is sufficient lube after drying it out. ****Do not use this on carbon pots****. Only this type of switch contacts please.  The contacts in this type of switch dont take kindly to switch cleaners..posted thread here abt this some time back.

If after correcting the cap, and cleaning all pots/switches the problem still persists, then I suspect leaky electrolytics.

Thanks
Marantz123.

Offline Aqualung

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Re: Amplifier pop
« Reply #2 on: January 23, 2018, 12:00:55 PM »
Thanks Marantz - yes, indeed a typo. It is a 0.047uF cap.
Next step is a "service" - switch and pot clean.  :thumbs:
I love music - analog and digital. Even listening to the Blues makes me happy. During the day I coach and counsel, after hours I indulge in my second passion - listening to vinyl and restoring turntables. Some I keep, some I sell...

Offline HBAutomation

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Re: Amplifier pop
« Reply #3 on: January 23, 2018, 12:18:12 PM »
I have the same with the same. Its been relegated to the cupboard, pending a service. Which I'll do one day :roll:
Really nice little units for phono!
When You Come to a Fork in the Road, Take It!            [Yogi Berra]

Offline Aqualung

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Re: Amplifier pop
« Reply #4 on: February 10, 2018, 06:45:42 PM »
Final update:

My first spark suppression cap was soldered to the mains before the On/Off switch.
I then soldered in a second 0.047uF cap AFTER the On/Off switch (as I noticed was done (in the factory) in another amp) and the problem went away completely.
Thanks for all the help!
A
I love music - analog and digital. Even listening to the Blues makes me happy. During the day I coach and counsel, after hours I indulge in my second passion - listening to vinyl and restoring turntables. Some I keep, some I sell...

Offline baz

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Re: Amplifier pop
« Reply #5 on: February 14, 2018, 09:12:37 AM »
Look at the main Caps if leaking you going  to have a problem!! i have change the caps to a old Pioneer having the same problem and fix it  :2thumbs: