Bang...there goes the power!

[eyedee]

I installed an I.C.E. system in my Rex a couple of weeks back, and Ive started to get a problem where their is a substancial 'bang' from the speakers, followed by the head unit shutting itseld down for 2 seconds and restarting itself! I bought a 1.5 Farad Cap hoping to sort the problem, and although I think its pretty straight forward, I'd just like to double check Im not going to wire it up wrong! The instructions are a picture, and they show an output from the amplifier going to the negative battery terminal via the Farad Cap. Im guessing that this actually should be the output to ground from the amplifier, going to the grounding point in the boot of the car via the farad cap. Is that right??? The instructions given with the Farad Cap (A) and those I think are correct (B) are as follows:

[sdminus]

Am i correct in thinking there are 3 terminals on your Cap?.
Neither are making sense to me. It seems to defy how a capacitor works. Ie a capacitor works by charging up untill the potential drops, at which point it discharges to give desired effect. Ie phase shift of smoothing out of the wave form. Even though it is not sinisodal (spelling may be off) the Dc system will not be ripple free because it is bridge rectified at the alternator (AC) and there is no power factor correction in the circuit. Surley the cap provides this and needs to be in phase to put the rectified wave out of phase in order to remove the peaks and troffs associated with this system.


Why did you get a cap, were you getting a lot of volt drop????? Do you know how much current your system is drawing.

Scott (JIB Approved Electrician)

[eyedee]

Hi. The cap does have three terminals as shown on the pic. The first image (A) is the actual image (which was initially labelled instructions) which came with the power cap. I purchased it because of the problem I described in my last email. I purchased the stereo setup from an I.C.E. dealer in London who recommeded I buy a 1.5 Farad Cap to aid the continual power stream being provided to the Amplifier (600W JBL GTO) and stop the cutting out problem I described.

I have never had a power cap before, so Im a bit lost now! :rolleyes: Any ideas?

cheers mate :)

[sdminus]

Ok i only have 10 years of electrical experiance to back me up here (non of which is automotive) But i cap works in the same way regardless of application. I dont think either is correct. The cap will be no good in the negative part of the cycle. Ie on the 0 vdc line which is where it is currently.
Please dont quote me on this but your supply needs to charge the plates of the cap untill the supply starts to drop off. This could be caused by volt drop or a ripple in the supply wave form. At this point the cap will discharge. To do this the cap needs to supply. Try this site.

http://www.caraudiohelp.com/car_audio_capacitor_installation/car_audio_capacitor_installation.htm

If i was you i would consult a company which knows the score. Personally i would say you dont need a cap. The alternator on a fd for example has a 80A rectifier so should not need the power factor correction of a cap. I would expect to hear the alternator load up and the engine revs dip when under load rather than it droping out.
This would suggest to me that a relay is chatering or droping out.
Scott

Ps i aint ever seen a cap with 3 seperate terminals. one may be used to ground the can

[James S]

the third terminal you are talking about is a remote terminal which basicly lets the capacitor know when power is getting to the amplifier.

i've got my capacitor connected up pretty much the same way as picture b and it seems to work fine. Before i conected the capacitor my revs were falling and causing the engine to cut out, after i connected the capacitor the problem was solved :D

:wave

[Tintin]

I think I know what your problem is

it goes a bit like this - you turn the ignition on and the system comes on , you start the car and you get a bang from the sub and the stereo turns off for a second

You need a little doofer , ground loop isolater or summat , I'll find out what its called and let you know , I have the same problem

I'LL BE BACK !!!!!

[Tintin]

Can't find the exact info I was looking for but I'm sure thats the doofer , best bet would be to go to an audio place explain the problem , mention a gound loop isolator and see what they say

[Mark C]

Looks to me like the cap just needs to be wired in parallel with all the power connections on the amp. IE + on the amp goes to + on the cap negative to negative and acc on the cap to remote switch on on the amp.

[eyedee]

Hi,

I spoke to a couple of real nice guys on a stereo stand at the Pod last Sunday, and they said its worth hooking the Frad Cap up (didnt recommend how they would do it) which may help any power probs to the amp (I dont think it has any mind you) and they said to ground the head unit as is is the panasonic single din CD player that keeps turning off with a bang (through the speakers) and resetting itself. I guess I'll have to try everything hopefully to find and fix the problem.

Cheers all

[eyedee]

Hmm, last night, I started the car and started the stereo and after approx 1 minute, whilst the emgine was still idling high at 1500rpm I began to drive forward. The normal bang came, but this time it knocked the car out and the engine just died! Am I right in thinking the REX will draw more power from the battery at startup and then draws less power once the alternators had a chance to work as the car is driven - if so, maybe the stereo drew so much power from the battery for a split second/moment that the engine didnt have enough power and therefore stopped?!? Anyone with a more technically tuned mind (that will be most of you then! ;) ) help fill me in?

Cheers

[sdminus]

Your alternator will be hard chraging the battery at his point. I think it takes about 8 miles to recover the charge lost during starting.
Scott

[craigr]

I'm not expert on all things electrical, but in my small experience of doing ICEy things in my cars, I would be suspicious of a dodgy ground connection on your amp or headunit. I would also check the headunit remote power on cable that gives the amp a signal to fire up. I had a few problems with an amp turning on and off with the associated bang and it turned out there was a bad connection there.

[davegttph1]

I thought caps we're supposed to work in series to what ever is being powered? isnt it supposed to store the power and filter it through rather than massive amounts of power being drawn at once from the battery?

looks to me that its wired wrong...

[davegttph1]

Shouldnt the Cap be wired direct to the battery, THEN wired to the amp? otherwise surely the Amp AND the cap and drawing mucho power and sapping the engine... definately think its the wrong way round....

[eyedee]

Which ones the wrong way round davegttph1? A or B? I havent actually fitted the farad cap yet - Ive been so busy with other things. But I have discovered over the past few days that the 'bang' through the speakers is now mostly happening when you drive over a nasty bit of road such as a pot hole or a line of cement on motorways connecting a new and old bit og road surface etc. I am going to have to fit a digital camcorder on the amp in the boot and go for a drive. Then when the power pops, check the footage to see if its actually just the head unit that causing the problem or if the amp in the boot dies for a split second too.

Sometimes the headunit resets and the welcome screen pops up, but sometimes the panel just goes blank for a second and then it reappears continuing the cd from where it had got to!!!