Amp working intermittently.

On Holiday · 22 Nov 2015 at 12:45

Apologies if this is somewhat long-winded, just giving a background

I bought a new (to me) car on Tuesday and it had an old Kenwood KVT-617DVD in which I swapped out for my Alpine..

The Kenwood had its own receiver unit which had to be removed and therefore the head unit to the amps had to be re-cabled - this was done on Friday.

It ended up being a 6-7 hour job at the dealer I got it from as the rear speakers were strangely cabled directly to the head unit too even though the cables were there from the amp (not plugged in at either end though) to the rear doors.

We tested it and it all worked fine at the dealers garage, I drove for an hour to home, fine.

The next morning (yesterday) - when I first start the car, the output is intermittent, I check the amp and it's flicking into Protect Mode every 5-10 seconds, so I leave the head unit off and drive to work.

Come 4pm when I'm going home, I start the car, turn the head unit back on and it's working fine with no problem.

Same issue has happened today - didn't work in the morning, now it's fine.

What could it be?

- I have unplugged the rear speakers from the amp as I thought perhaps that may be why they were not connected to it in the first place.

Advice or suggestions greatly appreciated

Head Unit: Alpine IDE-178BT
Amps: Infinity 475a 4channel & 2 channel.
Speakers: Front Alpine something (I think)
Rear Speakers: Infinity Kappa

lord filbuster · 22 Nov 2015 at 13:26

Are any of the connectors corroded or not seated properly?

n14hta · 22 Nov 2015 at 13:31

Check if the ground to the amp is secure and not moving about slightly.

On Holiday · 22 Nov 2015 at 13:35

All the connectors are new and securely attached.

I will check the ground to the amp (if I can find it) now.

Just weird that it wants to work fine on the way home from work but not first thing in the morning?

EDIT: It's not working at the moment - keeps flicking into protect mode.

Going to pull the seats up now and have a look.

p1RATE · 22 Nov 2015 at 14:50

Sounds like it will be the ground. It should be the first thing you check anyway

iaind · 22 Nov 2015 at 15:34

If it's flickering protect then it's more likely to be on the speaker side - it'll be one of the speaker cables touching ground, shorted or a blown coil.

n14hta · 24 Nov 2015 at 09:13

Did you manage to sort it out?

On Holiday · 24 Nov 2015 at 10:05

I've not had time to look at it properly unfortunately. I finish work today for the week so will take a look at everything again soon.

I put a Multimeter on "+12v and ground" and "Remote and ground" - both display 14.43 to 14.46v even when it flicks into protect mode.

Yesterday evening on the way home, start the car - intermittent for a few minutes, I decided to just leave the head unit on this time and after a few minutes it was fine.

Same again this morning, first few minutes it's not happy, after that it's fine.

iaind · 24 Nov 2015 at 17:23

Like I said, it's on the speaker side. Disconnect the speakers one by one until it stops flickering. Then check the wiring to that speaker and replace the speaker itself - if they've been run too hard or with an amp that couldn't drive them properly then the coils may have shorted

On Holiday · 9 Dec 2015 at 15:45

Update to this.

Last couple of weeks it has been fine, though the weather warmed up again.. Showing 9'c on the car "outside" temp display.

This morning, cold, 5'c.
Amp is flicking into protect mode again - this time it didn't stay on at all during the 30 minute journey at 7:30am.. Tried it again just now and it's still doing the same.

- Fuses are fine.
- Grounding cable is fine.
- I had unplugged all the speaker cables at the amp end so only the sub was connected and booming away - it still goes into protect mode every few seconds.

Going to double check the power cables to the amp next.

My friend has suggested it could be a dry joint issue.