help repairing JL 500/5

[splicer13]

Current behavior:
turns on, runs for 10 or so seconds with distortion. Towards the end of those ten seconds i hear a faint very high pitched whine which sounds to be above 10khz. Then it shuts down for around 2 seconds, turns back on, and the cycle starts over. I suppose the whine is coming from one of the toroids in the power supply area but I have not tracked it down. When it is whining it seems like it is drawing a lot of current. I have not measured how much but it is enough to draw down my 12v power supply voltage a bit.
Any pointers would be appreciated.

[Perry Babin]

All channels?

These amps are VERY sensitive to voltage drop and dips that are so short that they don't show up on a multimeter will cause it to shut down. Are you sure that this isn't the problem?

[splicer13]

Originally Posted by Perry Babin

All channels?

These amps are VERY sensitive to voltage drop and dips that are so short that they don't show up on a multimeter will cause it to shut down. Are you sure that this isn't the problem?

All channels were out when it was in the car. I took it in, put it on the bench, and it seems to be doing the same thing there (the repetitive turning off). It is possible both the car battery and bench power supply have problems but the JL 300/4 I swapped into the car is not having a problem and neither have other amps I have run off the bench PS so I think that is unlikely.

[Perry Babin]

Post the voltage on all 10 pins of the connector shown in the photo (view full size to read numbering scheme).

Post one set before it whines and one set after it whines.

Before
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:

After
Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:

[splicer13]

Originally Posted by Perry Babin

Post the voltage on all 10 pins of the connector shown in the photo (view full size to read numbering scheme).

I do not see a connector like that on my amp. Where would it be located? The caption on that picture says it is for a 500/1 and I have a 500/5 so that may be the issue...

Thanks,
Matt

[Perry Babin]

I didn't have a photo for the 500/5 with the numbers on it. Your amp has the same connector. It's labeled P800 on the board and it's near the power/ground terminals.

[splicer13]

P800, found it on the input board. Will take the measurements tonight.

[splicer13]

Originally Posted by Perry Babin

I didn't have a photo for the 500/5 with the numbers on it. Your amp has the same connector. It's labeled P800 on the board and it's near the power/ground terminals.

OK here are the measurements. I am taking pin 1 as the one closest to the power connector and working counterclockwise. The second numbers are when it whines.

1. as high as 18v, most of the time 11, falling to .5, then briefly back to 18
2. 45mv down to -20V
3. 11.3 dropping to 9.5
4. 11.4 dropping to 9.5
5 45mv rising to 2
6. 44mv up to 2v
7. 11.4v falling to 10
8. 12v falling to 10.6
9. 5v rising to 5.7
10. 12v falling to 9.6

[Perry Babin]

Are they numbered like those in the photo?

If not, repost them as they are numbered on the photo.

[splicer13]

Originally Posted by Perry Babin

Are they numbered like those in the photo?

If not, repost them as they are numbered on the photo.

Well, it is not the same board as the one shown in your picture so I don't see how to compare. I have included a picture I took. What I am calling pin 1 is the one in the top left.