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Fuse and Capacitor advice
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Return to top of page · Post #: 16 · Written at 6:48:53 PM on 23 April 2015.
	Tinkera123 Location: Melbourne, VIC Member since 5 October 2009 Member #: 555 Postcount: 465
GTC ...... post #13 ....... had a good look at this circuit today and you are exactly right, including 3 transistors and filter to prevent low frequency tripping ...... hard turn off under a fault condition with a soft turn on. Relay wouldn't activate due to a fault condition on output of one channel ..... about 38vdc ..... protection circuit functions properly now that I have diconnected that channel. Now to track down that 38vdc ...... starting to wonder how long this piece of string is ...... Cheers, Ian ‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾ Cheers, Ian

Return to top of page · Post #: 17 · Written at 7:25:44 PM on 23 April 2015.
	GTC Location: Sydney, NSW Member since 28 January 2011 Member #: 823 Postcount: 6687
starting to wonder how long this piece of string is I think we've all been there at one time or another. I have more than once, and that's why I avoid taking on repairs of other people's stuff these days. I never charged for such work, other than for parts, but I have a very long job list of my own spanning all sorts of stuff, and now that is all I concern myself with in the workshop.

Return to top of page · Post #: 18 · Written at 9:57:02 PM on 23 April 2015.
	TV Collector Location: Ballarat, VIC Member since 4 January 2011 Member #: 803 Postcount: 456
The protection relay has a dual function. The first is to isolate the speakers during the turn on - turn off power transitions of the amplifier to prevent speaker thump. The second function is to monitor the amplifier output and disconnect the speakers if a DC offset condition occurs. A quick check of the amp would be to measure the DC voltage on the amp outputs with respect to ground before the protection relay. Anything more than around 50 to 100mV indicates the amplifier has excessive DC offset and a possible fault. Many amps have an trimpot to make fine adjustments to the DC offset.

Return to top of page · Post #: 19 · Written at 7:43:09 PM on 24 April 2015.
	Tinkera123 Location: Melbourne, VIC Member since 5 October 2009 Member #: 555 Postcount: 465
A quick update ..... fixed dc offset problem ..... open resistor preventing offset transistor TR 06 from turning on. However, nothing from speakers as yet ...... so the end of that piece of string is still out of sight ......😂 Something I forgot to mention .... the dc protection circuit diagram was incorrect. For anyone looking at the circuit, the circuit board has a connection between anodes of D23 and D13 .... circuit is now much easier to understand .....😀 Cheers, Ian ‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾ Cheers, Ian

Return to top of page · Post #: 20 · Written at 5:28:53 PM on 27 April 2015.
	Tinkera123 Location: Melbourne, VIC Member since 5 October 2009 Member #: 555 Postcount: 465
Slowly, but surely I have found all the faults with the Sansui 6600 amplifier and she is now alive and working well ...... Cheers, Ian ‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾ Cheers, Ian

Return to top of page · Post #: 21 · Written at 5:41:51 PM on 27 April 2015.
	GTC Location: Sydney, NSW Member since 28 January 2011 Member #: 823 Postcount: 6687
Good job. In future, I will refer any Sansui problems your way

Return to top of page · Post #: 22 · Written at 8:10:55 PM on 27 April 2015.
	Tinkera123 Location: Melbourne, VIC Member since 5 October 2009 Member #: 555 Postcount: 465
...... not forgetting lots of help from my friends ....... Thanks, GTC ‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾ Cheers, Ian

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