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This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022

 

BC9500 Output Amp Popping Caps

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Garten
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Garten Posted: Sun, Nov 13 2016 1:53 PM

Hi all,

My BC9500 strated sounding really flat (and giving off a faint hum, but not 50HZ hum!)

As ther was also a ttape issue with a highpitched noise that had some mechnaical reasons...So i decided to take it apart.

The only visible issue was this 60C14 seems blown and also that it differs in type (though not in spec) to 60C16 while still sharing partnr.

Can this by itself has cause superflat sound and also the need to crank the volume up half way for a bit of umpf...?
as tne old addage goes, no smoke without fire.. so any ideas outhere what the root cause of this failiure could lie, ..or only a component failire (I have read the "Roederstein death" comments on the forum)...
thanks
/g

BM 2000 *1974, 2x BM 1200, BM 1001, BG 1200, BG CD X, BC9500,BM3300,Bcord 3300, BG CD3300, Beovox Cona, Beovox CX100, Beovox 1200, Beovox RL60.2

tournedos
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tournedos replied on Mon, Nov 14 2016 7:47 AM

60C14 and -16 are part of the supply voltage bypass & filtering for the output amps, so having one or both essentially dead is certainly going to affect the sound.

Those Roederstein types are often going bad at this age, and being sandwiched between two high power resistors is not going to help that particular cap. Possibly the other one has been replaced already.

--mika

Garten
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Garten replied on Mon, Nov 14 2016 9:38 AM

thanks, lets hope it is heat and crappy ROE..

regarding the otherone having been replace.. this BC has been in the family since it was bought in Hamburg in the early 90:ies.. I can't remember it ever been repaired. And there is a lot of these unmatched odd couple Caps allover.. looks almost like these PCB's were handbuilt and they took whatever caps they had in stock that held up to the needed spec, also sourced from so many different suppliers, sometimes for the same values and configurations... like streaching legs when thay had run out of axials...

In anycase, ill probably get back to you all, as i do this overhaul and cross my comfortzone of skill a few times...

 

BM 2000 *1974, 2x BM 1200, BM 1001, BG 1200, BG CD X, BC9500,BM3300,Bcord 3300, BG CD3300, Beovox Cona, Beovox CX100, Beovox 1200, Beovox RL60.2

Garten
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Garten replied on Sun, Feb 12 2017 8:14 PM

after a few months of not having any time to do anything, i have just been listening to the now functioning 9500.. but one thing realy is strange...

I always have to have the volume to 50-60% to play normal level of sound.. with my BM4400 i olny have to take it to nr 2-3 with the same speakers to same level.

Independant of input /source....

I can't remember this being the case a few years back.. what is the first think that comes to mind? Can't be the caps, toal overhaul on those done already.... and volume control and leds respons, and it does get louder and undistorted, sounds good, but just lacks the power it used to have it seems...

BM 2000 *1974, 2x BM 1200, BM 1001, BG 1200, BG CD X, BC9500,BM3300,Bcord 3300, BG CD3300, Beovox Cona, Beovox CX100, Beovox 1200, Beovox RL60.2

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