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Old 18th April 2011, 02:01 PM   #11
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Quote:
Originally Posted by Perry Babin View Post
Q1 and Q2.
okay, i just did a test of those transistors with a voltmeter and both read out at exactly 4.37 volts. is there anywhere i can rent a oscilloscope if i need it in this case?
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Old 18th April 2011, 02:21 PM   #12
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If they're identical, the FETs are likely OK. The rental of a scope would likely cost more than replacing the amp.

Does anything else in the amp look like it got hot?
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Old 18th April 2011, 02:33 PM   #13
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Quote:
Originally Posted by Perry Babin View Post
If they're identical, the FETs are likely OK. The rental of a scope would likely cost more than replacing the amp.

Does anything else in the amp look like it got hot?
none that i can see, smell, or feel while it's running. i don't notice any discolored resistors, circuit traces, etc.
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Old 18th April 2011, 04:00 PM   #14
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im thinking that it may just be that diode. maybe replacing it with the one perry mentioned will help...
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Old 18th April 2011, 09:08 PM   #15
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i found out that the 1n5366 diode is a zener diode and the 1n4003 i used is a regular diode. it might be that the noise is occurring when the diode is supposed to be allowing current to flow when the breakdown voltage reached the appropriate level but isnt because the 4003 is a regular diode that doesnt allow any to flow in the reverse direction at all. see Zener diode - Wikipedia, the free encyclopedia. i found this out thru the following datasheet: http://www.datasheetcatalog.org/data...n5333b-88b.pdf
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Old 18th April 2011, 10:44 PM   #16
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I think you should get the correct diode in it. It probably won't solve the problem but it will eliminate it as a possible fault.
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Old 19th April 2011, 07:12 PM   #17
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I think you should get the correct diode in it. It probably won't solve the problem but it will eliminate it as a possible fault.
gotcha on the diode. perry, i have also heard people with this model replacing the silver capacitors in the preamp card near the inputs because they leaked. out of curiosity, what symptoms would be present if those caps were bad in any way?
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Old 19th April 2011, 07:14 PM   #18
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The 10uF SMD caps leak and cause all sorts of problems but I've never heard of them causing the problem you're having. The primary filter capacitors may be causing it, however.
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Old 19th April 2011, 07:54 PM   #19
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The 10uF SMD caps leak and cause all sorts of problems but I've never heard of them causing the problem you're having. The primary filter capacitors may be causing it, however.
which ones are those?
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Old 19th April 2011, 10:57 PM   #20
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which ones are the filter caps?
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