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Old 23rd May 2011, 10:45 AM   #41
AndrewT is offline AndrewT  Scotland
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Anilva,
check the temperature of the first C in the rCrCCrCC. It takes the brunt of the ripple current and tends to use up all/most of the ripple capability of the capacitor.
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Old 23rd May 2011, 11:00 AM   #42
anilva is offline anilva  India
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Originally Posted by AndrewT View Post
Anilva,
check the temperature of the first C in the rCrCCrCC. It takes the brunt of the ripple current and tends to use up all/most of the ripple capability of the capacitor.
Thanks Andrew. It's warm but not hot. However the 'r's are pretty hot all over the PS. I have used Ceramic MPC 0.47 ohms, 5W resistors.

What is the right way. CCrCrCC?

Cheers.
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Old 23rd May 2011, 11:48 AM   #43
AndrewT is offline AndrewT  Scotland
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"It's warm but not hot".
Is it warmer than the partners?
Heat will shorten the life of the capacitor.
This will likely be the first capacitor in your PSU to fail or increase ESR with age. An increase in ESR will increase the hum at the amplifier and increase the heat in the capacitor.


I use RC and rC and Rc depending on the relative values of the Resistor and Capacitor.

The capacitance and inductance of an interconnect would generally be c & l (lower case L)
The resistance of a transformer secondary would be r.

The intermediate resistances could be 0r47/4 = 0r12 or 1r0 or 10r. 10r would definitely be R.
0r12 is r by my definition. 1r0 is debatable depending on the effective filtering turnover frequency relative to the frequency to be attenuated. Most writers tend not to differentiate between lower and higher values. The differentiation (r cf R, or c cf C, or l cf L) allows one to include RC filters or LC filters that are normally ignored in looking at a circuit. Inserting the r of the transformer is just such a case where it is normally ignored but can be a significant attenuator of some frequencies.
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Last edited by AndrewT; 23rd May 2011 at 11:52 AM.
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Old 24th May 2011, 07:06 PM   #44
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Originally Posted by anilva View Post
Finally, I fixed the nagging hum on my dual output Toshiba F5. Thanks to all the suggestions and help.

Based on a large number of suggestions from the members to increase the PSU capacitors, I have changed the PSU to a CRCCRCC configuration with a total of 110000 uF on each rail.

Cheers.
Congrats on the fix. CRCCRCC is the configuration I'm using (see my pics), and you're right--the amp is "dead silent". Glad you're enjoying the F5 now!
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