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Old 15th January 2013, 06:42 PM   #1111
Marra is offline Marra  United Kingdom
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Thanks Analog
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Old 15th January 2013, 06:54 PM   #1112
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You are welcome. The need for these caps has not been officially established. In my case they were clearly essential but, at least theoretically, they reduce the performance of the regulators. If your power supply does not oscillate, you are probably better off without them.
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Old 15th January 2013, 07:57 PM   #1113
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Someone had oscilations and cured them by using decoupling caps near the input section emitter EL caps....
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Old 15th January 2013, 09:03 PM   #1114
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Sadly, that didn't help. Bypassing them when voicing is probably a must, but first it has to work properly.
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Old 16th January 2013, 12:01 AM   #1115
hesener is offline hesener  Germany
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Originally Posted by analog_sa View Post
Sadly, that didn't help. Bypassing them when voicing is probably a must, but first it has to work properly.
I do have some ideas how to fix it, but before releasing them I want to verify (as is proper engineering practice). To do this, I need boards that are oscillating, hence a repeat of my offer - ANYBODY out there who has oscillating Paradise R3 boards, ship them to me and I promise a quick turnaround.

I do have a couple boards but havent found the time to look at them yet. I believe they are not oscillating though.....
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Old 16th January 2013, 07:54 AM   #1116
RCruz is offline RCruz  Switzerland
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Sadly, that didn't help. Bypassing them when voicing is probably a must, but first it has to work properly.
Do you have oscilations if the input is not shorted ?

What if you put a 10n cap in the input in parallel with cart load (input not shorted) ?
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Old 16th January 2013, 08:20 AM   #1117
Marra is offline Marra  United Kingdom
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My boards are powered and sat on a shelf with voltages as posted by Alfred in his replies to quan and pin 6 on one fluctuating around 0.5V and the other 1.5V.Outputs are fluctuating around 200mv.hopefully things will settle after a few days.Would it be better to case them up to aid things in settling?
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Old 16th January 2013, 10:30 AM   #1118
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Do you have oscilations if the input is not shorted ?

What if you put a 10n cap in the input in parallel with cart load (input not shorted) ?
Yes, it oscillates with open inputs as well. The 10nF reduced the oscillation amplitude several fold - it is now below 1mV p-p.
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Old 16th January 2013, 10:59 AM   #1119
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if you remove the boards away from the metal case... does it stop oscilating ?
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Old 16th January 2013, 11:58 AM   #1120
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I really don't think the metal case is much of a factor here. What it did, was remove all traces of low frequency mains related noise which made it easier to observe the oscillation on the scope. FWIW the boards are mounted on wood/rubber standoffs and are thus well distanced from the case.
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