Old Fisher 203 - "whump" when turning it on?

AintBaroque

Active Member
The Fisher 203 I have works fine, occasional scratchiness on some of the dials but the FM tuner is good even without an antenna, plays external inputs like my CD player great, etc.

However when I turn it on I hear a short-lived "whump" or heavy "click" sound that seems to come from the speakers that are connected. The speakers are dead quiet with no source and the sound turned up (that is, there is no hum in regular operation).

Any idea what this is caused by? Is it something to worry about?
 
Not to worry! Some older vintage units did not employ or use speaker protection circuits or relays in their designs. Simply turn off the speakers before powering up, then wait a few seconds, then turn on the speakers.

You should've heard the thump/buzz on my Pioneer SX-1010 when I was servicing my protection relay circuit when I had the contacts manually closed!
 
Not to worry! Some older vintage units did not employ or use speaker protection circuits or relays in their designs. Simply turn off the speakers before powering up, then wait a few seconds, then turn on the speakers.

You should've heard the thump/buzz on my Pioneer SX-1010 when I was servicing my protection relay circuit when I had the contacts manually closed!

I always turn the volume down to zero before turning it on, is that enough? So far the speakers are not damaged in any way...
 
You should switch the speakers off if you can. That thump is a surge of DC voltage.
 
+1 with Cademan. Caps charging up and a burst of DC. Turn off the speakers, turn on the unit, count to 2 and turn on the speakers. 90% of my gear doesn't have Protection circuit and do this.
 
I am not familiar with the 203 but have you got speaker switches on that thing?
 
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