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| Re: Kustom XII bi-amp [message #23634 is a reply to message #23583] |
Sun, 16 August 2015 13:40   |
chicagobill
Messages: 2006
Registered: April 2003
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Senior Member |
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A couple of questions. What are you using to drive this amp? It is a power amp so it is probably looking for at least 1 volt of signal to get full power output.
Are you still hooked up to the light bulb limiter?
As for your meter, that should do fine, the ohms reads resistance, the uF (micro Farad) is capacitance, the mA (micro Amp) is current and the voltages are for volts.
To test capacitors, the amp must be off and the power supplies drained. Pulling the plug and leaving the amp sit for a while will probably be enough to drain the caps, but you should test for voltage at the two main filter caps to be sure.
Set your meter to read dc volts. Hold the black lead to the black wires that connect two filter caps together. Now take the red meter lead and touch it to the screw terminal where the red wires are connected. Make note of the DC voltage reading. If the amp has been off for a while there should be less than a few volts there. Then touch the red lead to the screw terminal on top of the second cap where the green wires connect. The voltage reading there will be negative, so your meter will have some sort of minus sign in front of the reading.
When you are sure that there is no voltage left on the filter caps, set you meter to read capacitance, the uF position. Now hold the black lead on the black wire terminal and the red lead to the red terminal and see what reading you get. Some meters will read into the 1000's of uF and some won't, so see if you get a good stable reading. Then test the second cap by putting the black meter lead to the green terminal and the red lead to the black terminal. You can also test any of the small caps on the boards in the same way.
As for testing the operating voltage, you will need to have the amp turned on to test this. If you don't feel safe in doing this, then don't. If you want to try it, you will need to do exactly what I described in testing the caps for residual voltage, but with the amp turned on. If you have clip leads, you can use them to connect the meter to the caps before you turn on the amp and then just turn the amp on to read the meter and then turn if off again.
Just remember that woring on any amp that is plugged in and turned on is dangerous and can cause you physical harm.
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| Re: Kustom XII bi-amp [message #23637 is a reply to message #23583] |
Sun, 16 August 2015 22:41 |
chicagobill
Messages: 2006
Registered: April 2003
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Senior Member |
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It sounds to me like the caps still have a charge on them. OL (overload?) and then disc (discharge?). If the amp has been off for a while, try leaving the meter leads connected longer and see if you get a stable reading after the meter goes through the discharge cycle.
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| Re: Kustom XII bi-amp [message #23639 is a reply to message #23638] |
Mon, 17 August 2015 09:13 |
C4ster
Messages: 686
Registered: June 2001
Location: Mukwonago, WI (Milwaukee...
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Senior Member |
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Hi all, I have been following this post and I concur that a schematic is mandatory in this case, or any troubleshooting of amplifiers. But something just jumped out at me that I want to address. If you are comparing a K200 of any version, it has preamps that will take a low level signal, maybe 30mV or so and amplify it to the full output rating of an amp. Kustom amps have lots of preamp gain. If you then used that same signal without making any adjustments to it, and applying it to the Kustom XII, you WILL NOT get the same sound output as the K200. You are comparing apples to oranges. ChicagoBill is 100% correct about the levels necessary. Any power amp is designed to be driven from a mixer and subsequently, graphic equalizers, effects and other rack type equipment. These are line level sources, not instrument level sources that the K200 would be driven by. Sorry for the rant.
Conrad
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| Re: Kustom XII bi-amp [message #23653 is a reply to message #23652] |
Tue, 18 August 2015 08:16 |
C4ster
Messages: 686
Registered: June 2001
Location: Mukwonago, WI (Milwaukee...
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Senior Member |
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Steve,
Sometimes its just better to wait the storm out. These long threads sometimes just get further from the answer than closer.
Conrad
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| Re: Kustom XII bi-amp [message #23686 is a reply to message #23677] |
Wed, 19 August 2015 23:02 |
Iowa Boy
Messages: 767
Registered: June 2014
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Senior Member |
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Oh man that is just so wrong. Is there even a Kustom museum anywhere?
Family reunions are hard as hell to organize so I can imagine how difficult something like this would be. Maybe Vegas.....everyone would make an effort to go there and there are always cheap airline packages and hotel deals to be found not to mention a great weekend get away.
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