velleman k4700 speaker protection circuit

cyteen · 27th May 2005, 12:28 PM

I've just been putting this kit together and apart from getting the LEDs round the wrong way initially all went smoothly. However. when I test the unit by connecting PA on the right hand channel to V+ the relay fails to trip. When connecting PA to V- it trips fine. The left hand channel trips for both V+ and V-.

I was hoping someone would point me in the right direction.

Frank Berry · 27th May 2005, 12:33 PM

D4 may be installed backwards.

cyteen · 27th May 2005, 12:47 PM

Thanks for the quick reply, looking at D4 it seems to be consistant with the markings on the top of the pcb. Could I have applied too much heat at some point and killed instead?

moamps · 27th May 2005, 01:03 PM

Quote:

Originally posted by Frank Berry
D4 may be installed backwards.

Or D2 (in some cases).

Quote:

Originally posted by cyteen
Thanks for the quick reply, looking at D4 it seems to be consistant with the markings on the top of the pcb...

Repeat test procedure on right channel and measure DC voltage on both side of D4 for +V on input.

Regards,
Milan

cyteen · 27th May 2005, 01:23 PM

D2 also seems consistant with the pcb markings.

Voltage on the end away front the dark band of D4 is + and on the end with the band there is no voltage.

Frank Berry · 27th May 2005, 03:53 PM

Replace D4. It's open.

cyteen · 27th May 2005, 04:16 PM

Many thanks.

27th May 2005, 12:33 PM	#2
Frank Berry diyAudio Member Join Date: Sep 2003 Location: Midland, Michigan	D4 may be installed backwards. __________________ Frank

27th May 2005, 03:53 PM	#6
Frank Berry diyAudio Member Join Date: Sep 2003 Location: Midland, Michigan	Replace D4. It's open. __________________ Frank

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27th May 2005, 12:47 PM	#3
cyteen diyAudio Member Join Date: Mar 2004 Location: S.E	Thanks for the quick reply, looking at D4 it seems to be consistant with the markings on the top of the pcb. Could I have applied too much heat at some point and killed instead?

27th May 2005, 01:23 PM	#5
cyteen diyAudio Member Join Date: Mar 2004 Location: S.E	D2 also seems consistant with the pcb markings. Voltage on the end away front the dark band of D4 is + and on the end with the band there is no voltage.

27th May 2005, 04:16 PM	#7
cyteen diyAudio Member Join Date: Mar 2004 Location: S.E	Many thanks.

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