Hello to all on this site. I just purchased an Alpine 3502 and can't get it to turn on. the amplifier only has a din connection for the input. it only has 3 yellow wires. black and red ....the power and ground are 10 gauge and the smaller red wire appears to be 18 gauge. do I need a signal from the radio to get this amplifier to turn on? ...any help would be appreciated.
Be careful with leaky capacitors on this vintage of Alpine, quite a lot of them have gone bad and destroyed the PCB because the electrolyte soaked into it and turned it conductive.
thanks, I will be taking the top board off to take a look at the capacitors. It looks like a complicated process that involves de-soldering 6 spots on the circuit board.
the amp powered up. These were the readings. the power supply rail +28.2vdc and -28.2vdc..........the idle current= 3.2mv both channels ..............dc offset = 19mv, both channels ..but I was able to dial down to close 0mv. I decided to take the amplifier apart. another member on this site warned me about leaky glue which reminded me of a Yamaha m80 I recapped a while back and it did have a glue problem.
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Are you going to use it immediately?
Did you heat the solder connections on any of the capacitors? If so, they they smell like antifreeze?
Did you pull any and see signs of leakage?
Did you heat the solder connections on any of the capacitors? If so, they they smell like antifreeze?
Did you pull any and see signs of leakage?
I will pull them and report back. the fact that my offset was in the 19mv range makes me think I have some DC leakage.
I think the driver board is going to be easy. I can just order all audio grade replacements.. but the PWR supply board I've read requires low esr high ripple...so many options?
Electrolytics commonly have a 20% tolerance and often read on the low-side of their rating. All you pulled... no leaking and within tolerance at 40 years old.
The only caps that typically need low ESR are those on the primary side of the power supply and if it has an inductor (this amp has one), they are not really necessary. They certainly won't do any harm but no advantage.
Audio quality caps? Save your money.
The only caps that typically need low ESR are those on the primary side of the power supply and if it has an inductor (this amp has one), they are not really necessary. They certainly won't do any harm but no advantage.
Audio quality caps? Save your money.
Its not so much their value in microfarads, like Perry said they will often be within tolerance even at this age. Its the fact that many brands of capacitor from this time period are prone to capacitor plage, and the Elna’s used by Alpine in many of their amplifiers are no exception. The ones with snap in leads arent very likely to leak, but the others i would definitely replace as those are the ones that tend to spill their guts all over the board and ruin the amplifier. Its just good insurance for long term reliability.