Penta Mk3 loud pop on power up

[Nick Davison]

Hi All

I have a problem with one of my Mk3s the I’m hoping someone can help with.

 

With mains power on and no speaker plug connected, when I select left source on the speaker switch I get a loud Pop.  It also pops as I deselect to Off.

 

With the speaker connected to an old Avant Tv as the tv is turned on and therefore initiates the speaker, with the speaker switch set to either Left or Right, it pops.  Similarly as the TV de-selects the speaker when the TV is turned off it pops again.

 

Any help would be greatly appreciated.

Cheers

Nick

 

Location: Lincolnshire UK

Favourite Product: Penta 2&3

[pepps]

My Pentas pop too. They always have.

Location: Kent, UK

Favourite Product: Beosystem 6500

My B&O Icons:

[Nick Davison]

When I say pop it isn’t something that can be lived with, it’s more of a loud crack I guess and sounds like it will be doing some sort of damage.  One of my others has a quiet pop but nothing like this and as with yours peeps, totally acceptable.

Location: Lincolnshire UK

Favourite Product: Penta 2&3

[Nick Davison]

So the loud Pop or crack has been resolved.

I substituted various assemblies to isolate the problem which was isolated to PCB 22.

Diodes and resistors all checked and no faults.

So identified as IC2 chip.  Cost about £0.40! But postage et al was about £12! So I ordered a few in case anyone wants any?

Chip replaced and after assembly, the pop/crack has gone.

Of note the input switch does produce some interference when modulated with the speaker running, with the switch in a position there is no interference.  That may have indicated the switch was at fault.  When diagnosing the problem I substituted the door with a know good one and still had the pop/crack.  Contact cleaner was spayed into all switches.

I have spare IC2 Chips if anyone needs them, cost of packing and post plus the £0. 40!

 

I hope this post helps someone diagnose similar problems.

Nick

Location: Lincolnshire UK

Favourite Product: Penta 2&3

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