Alpine 1507 repair
 

Hi I have picked up an alpine 1507 that has an issue
With the RCA input terminals.

The terminals have been damaged, looks like it had been dropped and they have
lost 2 gold outer caps.

I decided to pull the whole terminal and replace it with
individual chassis mount type plugs as it was only making sound if you
moved the plugs about- they had worked loose on the board.

The amp seemed to work fine before I fitted the new RCA input plugs
it now produced a very distorted sound.

Any ideas?

The soldering points for the RCA inputs appear to lead into

Integrated Circuit NJM4560L DUAL OPERATIONAL AMPLIFIER

Could it be somehow damaged or shorted?

Post a photo of the new jacks showing how you connected them to the amp.

Hi Perry,

I have now removed the new plugs as I had actually wired the earth and positive signal leads the wrong way...... (they looked right when I matched them to the original plug but when I tested the plug with a meter it was obvious I got them the wrong way round)

I have removed the new plugs - there are just 6 wires extending from the board now.

The sound is very loud and distorted when I connect the center pin of my signal rca
( i am using an old sony cd tuner)

The green music light flashes when a sound source is added

I fear I may have caused the distortion issue by wiring the plug the wrong way.

You should not have caused any damage connecting the wires incorrectly.

Do you read 0 ohms between the shield grounds and the non-bridging speaker terminals?

Do the center conductors of the two input jacks connect directly to E101 and E102?

Hi Perry
The centre conductors lead to E101 and E102

I did the sheild ohm test with meter set on continuity
and the reading stayed on 1

It should read the same as when you touch the probes together.

My meter beeps and shows 000 when the probes
join, when I test the ground shield against the speaker terminals
there is no change or beep

Do you find any solder pads in the area of the RCA jacks that read 000 to the non-bridgingg speaker terminals?

Just checked, nothing reads 000