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Author Topic: Coliseum 300 crackle problem  (Read 2386 times)

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Offline protoz

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Coliseum 300 crackle problem
« on: March 23, 2005, 11:57:34 am »
I just got my Sunn back from the shop today and my tech cleaned the pots, fixed the loose handle and changed the cord to a grounded plug.

Great, that's what I asked for.

But he didn't fix the main problem I have with it: At certain frequencies I get a crackle. Easily reproduced by plucking the 5th fret on the E while in standard it goes crazy.

No amount of tweaking can get it to go away entirely. I dropped the EQ to flat, Overload just loud enough to hear it and I could still get it to go off.

Does anyone have any ideas on what this could be? He replaced a bad input jack but I have a feeling it may be the speaker jacks (both will make the crackle) or something a little more serious.
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Offline Don T.

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Coliseum 300 crackle problem
« Reply #1 on: March 23, 2005, 04:01:00 pm »
Hello:
 When dealing with frequency dependant noises in the past I have found them to be:
1. Bad cap and/or solderjoint in the EQ section of the pre amp
2. Bad IC in the EQ section of the preamp.
3. Broken PS filter cap solder joints.
4. Broken solder joint at the interconnect harness connector.
5. Speaker related problem.

The speaker jacks or wire could be suspect. Then there are those pesky bad compensation caps or resistors all along the signal chain including the power amp.
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Don T.

If it's too loud, you're too old.

Offline protoz

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Coliseum 300 crackle problem
« Reply #2 on: March 27, 2005, 11:14:43 pm »
Ouch, I'll take it back in this week and ask him to check the caps and the speaker jacks.

Whats the bad IC mean?

If my tech can't get ahold of the parts do you know where I can find replacement parts for the caps?

It's not a speaker problem as I tried it on a 1x15 and a 4x10 that I use another head with.
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Offline Isaac

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Coliseum 300 crackle problem
« Reply #3 on: April 17, 2005, 01:46:31 pm »
IC=Integrated Circuit

You might be able to narrow it down by running the preamp out to another amp, and by running another amp's preamp out into the Coliseum.
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Isaac

Offline protoz

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Coliseum 300 crackle problem
« Reply #4 on: April 21, 2005, 10:10:42 am »
Well I got it all fixed, there was a broken solder on two of the power transistors and possibly a messed up diode from what my tech found.  I'll be picking it up maybe tomorrow and getting to try it out sometime next week due to work.
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