Need Cambridge A500 help

mdelrossi · 11th February 2007, 04:50 PM

I just picked up a A500 the fuses on the main board keep blowing.
I was wondering if anyone had any ideas ?
Should I replace the SAP15's, and see what happens?
I saw in another thread , OzOnE_2k3 had some experiences repairing these , If you are out there could you chime in?
thanks in advance. I will contact Cambridge Audio and see if I could get a Schematic.
mdr

XEAGLEKEEPER · 11th February 2007, 05:34 PM

1.Check your rectifiers and capacitors in the power supply section.
2. Check for collector to emitter shorts on the final outputs.

mdelrossi · 11th February 2007, 07:28 PM

do I have to de-solder them or can i check them on the board?
thanks
I'm a neewb for now

mdr

jaycee · 11th February 2007, 08:58 PM

You should desolder the transistors to check them.

You may also want to check the MJE340/350 transistors as these could've gotten fried as well.

XEAGLEKEEPER · 11th February 2007, 09:01 PM

Do you know how to check a diode or rectifier with a dmm. Do you have a dmm. To answer your question ideally yes, lift one side of the diode. If you have a bridged rectifier it would be best to removed from board.

mdelrossi · 11th February 2007, 10:27 PM

I've got a DMM, but looking to get one that is also an LCR meter. Any thoughts on an inexpensive one?
Thanks for your advice I'll set apart some time tomorrow to test them.
mdr

XEAGLEKEEPER · 11th February 2007, 10:48 PM

I picked up an el'cheapo lcr off of ebay no- name brand for $29 probably only good for ballpark measurements. Fluke has always be a good bet!

MikeW · 11th February 2007, 11:05 PM

Sometimes there is a burnt mark or other evidence of what blew up. I have blown the top right off some transistors.

mdelrossi · 2nd August 2007, 06:02 PM

Hi all.
I got the replacement SAP15 N&P.
Soldered them in and the amp doesn't blow, But the channel that I replaced the SAP's has a lot of static like you are trying to connect a speaker with the amp on. I have the schematic that Cambridge Audio was kind enough to send me.
here
Any help would be appreciated.
thanks
mdr

XEAGLEKEEPER · 2nd August 2007, 10:30 PM

mdelrossi
First lets see if your power supply is working. I need to know what the voltages are on pins 2 & 3 of U203 and U204.

11th February 2007, 04:50 PM	#1
mdelrossi diyAudio Member Join Date: Feb 2005 Location: ny	Need Cambridge A500 help I just picked up a A500 the fuses on the main board keep blowing. I was wondering if anyone had any ideas ? Should I replace the SAP15's, and see what happens? I saw in another thread , OzOnE_2k3 had some experiences repairing these , If you are out there could you chime in? thanks in advance. I will contact Cambridge Audio and see if I could get a Schematic. mdr

11th February 2007, 05:34 PM	#2
XEAGLEKEEPER diyAudio Member Join Date: Jan 2006 Location: central Iowa	1.Check your rectifiers and capacitors in the power supply section. 2. Check for collector to emitter shorts on the final outputs. __________________ Ret. USAF... AKA- Avionic * Solder slinger for hire...*

11th February 2007, 09:01 PM	#5
XEAGLEKEEPER diyAudio Member Join Date: Jan 2006 Location: central Iowa	Do you know how to check a diode or rectifier with a dmm. Do you have a dmm. To answer your question ideally yes, lift one side of the diode. If you have a bridged rectifier it would be best to removed from board. __________________ Ret. USAF... AKA- Avionic * Solder slinger for hire...*

11th February 2007, 10:48 PM	#7
XEAGLEKEEPER diyAudio Member Join Date: Jan 2006 Location: central Iowa	I picked up an el'cheapo lcr off of ebay no- name brand for $29 probably only good for ballpark measurements. Fluke has always be a good bet! __________________ Ret. USAF... AKA- Avionic * Solder slinger for hire...*

11th February 2007, 11:05 PM	#8
MikeW diyAudio Member Join Date: Sep 2002 Location: North of Boston	Take a look Sometimes there is a burnt mark or other evidence of what blew up. I have blown the top right off some transistors. __________________ MikeW


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11th February 2007, 07:28 PM	#3
mdelrossi diyAudio Member Join Date: Feb 2005 Location: ny	do I have to de-solder them or can i check them on the board? thanks I'm a neewb for now mdr

11th February 2007, 08:58 PM	#4
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	You should desolder the transistors to check them. You may also want to check the MJE340/350 transistors as these could've gotten fried as well.

11th February 2007, 10:27 PM	#6
mdelrossi diyAudio Member Join Date: Feb 2005 Location: ny	I've got a DMM, but looking to get one that is also an LCR meter. Any thoughts on an inexpensive one? Thanks for your advice I'll set apart some time tomorrow to test them. mdr

2nd August 2007, 06:02 PM	#9
mdelrossi diyAudio Member Join Date: Feb 2005 Location: ny	Hi all. I got the replacement SAP15 N&P. Soldered them in and the amp doesn't blow, But the channel that I replaced the SAP's has a lot of static like you are trying to connect a speaker with the amp on. I have the schematic that Cambridge Audio was kind enough to send me. here Any help would be appreciated. thanks mdr

2nd August 2007, 10:30 PM	#10
XEAGLEKEEPER diyAudio Member Join Date: Jan 2006 Location: central Iowa	mdelrossi First lets see if your power supply is working. I need to know what the voltages are on pins 2 & 3 of U203 and U204. __________________ Ret. USAF... AKA- Avionic * Solder slinger for hire...*

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