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Old 6th June 2013, 06:38 PM   #3601
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I may be too quick to say that the voltage across the TL431 is stable. It is actually fluctuating at a range of about 30mV, whereas the other side is stable to at least 10mV (measurement limit). As to why it is so, I couldn't find out why. Measuring continuity between components , and checking visually, there seem to be nothing wrong. May be the TL431 is bad.
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Old 6th June 2013, 07:58 PM   #3602
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Quote:
Originally Posted by Navyblue View Post
I may be too quick to say that the voltage across the TL431 is stable. It is actually fluctuating at a range of about 30mV, whereas the other side is stable to at least 10mV (measurement limit). As to why it is so, I couldn't find out why. Measuring continuity between components , and checking visually, there seem to be nothing wrong. May be the TL431 is bad.
TL431 is not that costly replace it if you want. So the out put is stable ? If it below 10mv after it warms up run with it .
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Old 13th June 2013, 08:28 PM   #3603
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I replaced the TL431, but it doesn't help.

Since then I tried a lot of stuffs, and finally be able to narrow down the problem, which is at C1. Here are the gist.

- The reason that the DC fluctuation at output symptom is voltage across TL431 isn't as still as it can be.
- When I soldered a 220F electrolytic capacitor at C1, the problem appears.
- Replacing the 220F electrolytic capacitor does not solve the problem.
- Soldering a 47F film cap largely solved the problem, but soldering 220F electrolytic capacitor on it brings the problem back.
- If I connect the 220F electrolytic capacitor through wire with alligator clips, the problem disappears.
- If I clip the leads of the 220F electrolytic capacitor directly without the wire, the problem came back.

So I thought, may be I need the resirtance of the wire. So I tried adding a resistor (1Ω, 5Ω and 22Ω). If I clip the resistor leads directly, the problem remains. If I connect the resistor through wire with alligator clips, the problem disappear.

Why is it that the wire with alligator clips seems to posses magical property? Any ideas?

Last edited by Navyblue; 13th June 2013 at 08:33 PM.
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Old 13th June 2013, 09:17 PM   #3604
Zen Mod is offline Zen Mod  Serbia
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it's dirty (pic)

so , pics .

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Old 15th June 2013, 02:30 PM   #3605
Dzius is offline Dzius  Poland
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I've built 4 chanel F4 on IRFP240/9240 and everything seem to all right exept one thing. Both sides of my F4 are playing relatively dry comparing to F3 or F5. So I recon timbre of music to be not so impressive I expected. Simlilary like "Navyblue" I changed 220uF caps for different Elna silmic from differente source (thought the first ones were fake) but that didn't cure the problem. I sounds exactly the same. Any idea how it can be or just it's just like that ?
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Old 15th June 2013, 02:33 PM   #3606
6L6 is offline 6L6  United States
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What preamp are you using?

The F4 has almost no sound of it's own and passes on the character of the preamp.
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Old 15th June 2013, 03:50 PM   #3607
generg is offline generg  Germany
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Default they all sound different....

and besides what 6L6 said, I would read Sarajans 6moons reviews of the F4 included especially in the F5 review and the J2 review and see if you can agree with some of his words....
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Old 15th June 2013, 03:59 PM   #3608
Zen Mod is offline Zen Mod  Serbia
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ACA via small cap driving some squawker and F4 , driving woof .

woofwoof
squeeksqueek
gollugollum

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Old 15th June 2013, 04:12 PM   #3609
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Disregard Srajan. He likes F5
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Old 15th June 2013, 04:15 PM   #3610
generg is offline generg  Germany
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I thought it was F6.....
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