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 Post subject: NEED HELP WITH A BOGEN DB130 MONO TUBE AMP
PostPosted: Jul Wed 10, 2019 4:19 pm 
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Joined: Jul Wed 10, 2019 4:11 pm
Posts: 5
Looking for an expert on Bogen amps
This amp has been fully recapped
All voltages check nice. Runs very very quiet
Scratchy volume. Not the pot
Here is what I see
This amp has a adjustable damping factor
You turn on the damping switch and adjust pot until an indicator light starts flashing
Turn off switch and play music
THIS AMP...
With the damping switch OFF the indicator light flashes with the beat of the music
WHATS GOING ON???


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 Post subject: Re: NEED HELP WITH A BOGEN DB130 MONO TUBE AMP
PostPosted: Jul Wed 10, 2019 9:19 pm 
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Joined: Nov Sat 07, 2009 11:37 pm
Posts: 2158
Location: Sayreville, NJ 08872
Why not provide us with at least a schematic to help analyze the circuit rather then having a bunch of people guess.

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 Post subject: Re: NEED HELP WITH A BOGEN DB130 MONO TUBE AMP
PostPosted: Jul Wed 10, 2019 9:41 pm 
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Joined: Sep Tue 15, 2015 1:16 am
Posts: 620
Location: 18424 PA
Let's just guess. Bad cap going to volume pot. Damping switch is wired backwards.


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 Post subject: Re: NEED HELP WITH A BOGEN DB130 MONO TUBE AMP
PostPosted: Jul Wed 10, 2019 10:32 pm 
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Joined: Jul Wed 10, 2019 4:11 pm
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Volume pot has 2 of those pack of firecracker looking devices that houses caps and resistors in one little brown bundle
Damping switch was never disturbed since the factory
I,ll try and download a schematic


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 Post subject: Re: NEED HELP WITH A BOGEN DB130 MONO TUBE AMP
PostPosted: Jul Wed 10, 2019 10:34 pm 
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Joined: Jul Wed 10, 2019 4:11 pm
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Was hoping a Bogen DB130 owner with a similar issue wouls spot this post
Until then it will be hit and miss till I figure it out


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 Post subject: Re: NEED HELP WITH A BOGEN DB130 MONO TUBE AMP
PostPosted: Jul Thu 11, 2019 4:30 am 
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Joined: Feb Wed 04, 2015 12:26 am
Posts: 934
If this amp has what call the "firecracker" pack, this is actually a couplet, and it has caps in it. There's a good chance this needs to be rebuilt.

Go through and thoroughly clean the tube sockets and verify the preamp tubes are good. A bad preamp tube can cause scratchiness and popping.


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 Post subject: Re: NEED HELP WITH A BOGEN DB130 MONO TUBE AMP
PostPosted: Jul Thu 11, 2019 4:46 am 
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Joined: Dec Tue 01, 2015 5:31 am
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Location: Columbus Ohio
good thread on AudioKarma covering this amp and some mods, couple experts there.
https://audiokarma.org/forums/index.php ... st-2187633

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 Post subject: Re: NEED HELP WITH A BOGEN DB130 MONO TUBE AMP
PostPosted: Jul Thu 11, 2019 2:37 pm 
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Joined: Jul Wed 10, 2019 4:11 pm
Posts: 5
When rebuilding this "couplet", which type capacitor should I use?


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 Post subject: Re: NEED HELP WITH A BOGEN DB130 MONO TUBE AMP
PostPosted: Jul Thu 11, 2019 4:55 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3324
Location: Seattle WA US
For the 4700 pf caps I would use silver mica if I had any that big, otherwise good film caps.
For the 100 pf I would use silver mica.
That said, the original couplate probably used ceramic caps in all three locations, and you probably wouldnt notice the difference unless you are handicapped with a golden ear.

-just my opinion & prejudices,
Chuck K7MCG


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 Post subject: Re: NEED HELP WITH A BOGEN DB130 MONO TUBE AMP
PostPosted: Jul Thu 11, 2019 5:42 pm 
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Joined: Jul Wed 10, 2019 4:11 pm
Posts: 5
over 40 years in manufacturing maybe possess a cast iron ear...


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 Post subject: Re: NEED HELP WITH A BOGEN DB130 MONO TUBE AMP
PostPosted: Jul Sat 13, 2019 9:03 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 23028
Location: Somers, CT
Could it be the damping indicator is part of the damping circuit feedback loop and is always in line?

Pete

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