Penta unusual loud noises. Like loud Scratching

5 replies
NI
Offline
nigel_surtees
Bronze
Posted February 16, 2024 at 03:29 GMT
#1643317
Hi All
I am new to this forum. I have a beocenter 9500 with Penta mk3 active speakers. I have had the system for about 5 years with no problems. About 6 months ago one speaker starting making very loud noises. they are hard to describe so I made a recording and attached it to this thread. Its like static scratching and very loud.

I have replaced all the electrolytic capacitors using a kit bought online. Its made no difference. During the overhaul I replaced the trimmers and set the dc offset which is now practically 0v.
Could it be the big power capacitors?  I didn't replace these as they were not in the kit.

Any ideas very welcome.

Thanks
EB
Offline
Epic B and O
Bronze
Posted February 16, 2024 at 23:44 GMT
Edited February 16, 2024 at 23:48 GMT
#1662508
Hey mate,

I have the same problem. It’s  corrosion on the input level switch.

I had a complete overhaul of my Penta’s, but unfortunately they missed the switch. So at the moment I’m living with it by switching the problem speaker to another input level.

I have the Beocenter 9500 also since the 90s. Absolutely love it.

I’ve attached photos of the problem switch.

if you find a fix please let me know.

hope this helps.

 
NI
Offline
nigel_surtees
Bronze
Posted February 17, 2024 at 00:34 GMT
#1662510
Ah really! Thanks for that, I would never have thought of looking at that switch. I'll have a play and see what I can do with it and let you know if I get anywhere.

Thanks again
HO
Offline
Homersaurus
Bronze
Posted February 20, 2024 at 19:38 GMT
#1662616
Would contact switch cleaner sprayed into the switches (when the control board is out of the Penta) be sufficient without resorting to physically dismantling the switches ?  I'd be interested to know the level of corrosion in the dismantled switches.
HO
Offline
Homersaurus
Bronze
Posted February 20, 2024 at 20:09 GMT
#1662618
An interesting cause of the fault though, which is very useful to know.  Switch cleaner/lubricant use as preventative maintenance might well be worth doing on the (pair of) Penta control board(s).
or
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