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
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
1.Check your rectifiers and capacitors in the power supply section.
2. Check for collector to emitter shorts on the final outputs.🙂
2. Check for collector to emitter shorts on the final outputs.🙂
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.
You may also want to check the MJE340/350 transistors as these could've gotten fried as well.
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.🙂
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
Thanks for your advice I'll set apart some time tomorrow to test them.
mdr
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!
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.
Sometimes there is a burnt mark or other evidence of what blew up. I have blown the top right off some transistors.
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
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
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.
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.
Should be ....U203
pin 2 + 30 vdc
pin 3 + 45 vdc
....U204
pin2 -30 vdc
pin3 -45 vdc
U203 and U204 are 30volt regulators on the power supply circuit board.
Dave
pin 2 + 30 vdc
pin 3 + 45 vdc
....U204
pin2 -30 vdc
pin3 -45 vdc
U203 and U204 are 30volt regulators on the power supply circuit board.
Dave
sorry I thought you meant across them. it's close 27 on the side that crackles and 27.5 on the other 45v in
thanks for your help
mdr
thanks for your help
mdr
I replaced the sap's on the channel that crackles the other channel sounds fine.
i get sound from both channels but one has a definite crackle and almost no bass. i switched the L and R inputs from the pre-amp board to the amp board and it stays in the same channel so it's on the amp board.
thanks so much for your time
mdr
i get sound from both channels but one has a definite crackle and almost no bass. i switched the L and R inputs from the pre-amp board to the amp board and it stays in the same channel so it's on the amp board.
thanks so much for your time
mdr
Did you go through the idle current adjustment procedure after replacing the outputs (last page of the pdf file)
🙁
uh no, I missed that, I'll do that next and report back.
I did play with that pot while listening and there was no change but I'll check that.
thanks.
sometimes i feel like a fool
uh no, I missed that, I'll do that next and report back.
I did play with that pot while listening and there was no change but I'll check that.
thanks.
sometimes i feel like a fool
it doesn't do a thing, I get 1.5v across S&E on the P transistor, and 0v on the N transistor.
Bad pot?
mdr
Bad pot?
mdr
On the bad channel with unit unplugged measure resistance across the VR201(202) from pin D of U201(205) to pin D of U202(306) should stabilize around 100 ohm if so pot is probably OK.
Check to make sure you put the P-chip and the N-chip in the correct place.If they are in the correct place then check your soldering for shorts(solder bridges) if solder connections are OK try a different pair of outputs. FYI when making idle current adjustment
accurate disconnect any audio input😉
Check to make sure you put the P-chip and the N-chip in the correct place.If they are in the correct place then check your soldering for shorts(solder bridges) if solder connections are OK try a different pair of outputs. FYI when making idle current adjustment
accurate disconnect any audio input😉
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