SD800.4 question

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gfunk_nz
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Joined: Wed Jul 04, 2007 4:23 pm

SD800.4 question

Post by gfunk_nz »

I have had an SD800.4 running in my car for a few years now with no issues, anyway, I installed a HO alternator which sits happily at around 15v as measured with my Fluke. The problem being is that during heavy loads from bass, when the bass stops the voltage spikes briefly to about 16v, it's such a quick spike the digital meter barely picks it up. When it does though the SD will shutdown and require the headunit to be turned off and back on again. I wanted to confirm that it is the protection circuit doing it and nothing else, but there's no info on what protection it has in it.
I would have never noticed the spike if it hadn't been for the PG shutting down, my big Sundown amp just carries on happy as.
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Mr. Wild
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Re: SD800.4 question

Post by Mr. Wild »

So how big is the sundown amp?

Most of the voltage drop at high current draw happens between the alternator and amps. Some voltage drop happens inside the alternator and is compensated by a voltage regulator. This regulator in not infinitely fast and when current draw suddenly stops voltage peaks a little.

If possible you should adjust the alternators output down a little. 15V and over is too high for lead-acid batteries. Also a big cap will smooth out brief voltage spikes.
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dwnrodeo
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Re: SD800.4 question

Post by dwnrodeo »

There was also a technical bulletin issued for that amp that warned of too high of voltage. I believe it was remedied in later versions of that amp, but the earlier ones were at risk.
XS2300, XS2500, XS2300, X200.4, X100.2, Ti21000.4, Roadster 66

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gfunk_nz
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Re: SD800.4 question

Post by gfunk_nz »

The sundown is a SAZ2500, I've removed the self exciting regulator a put a 3 wire one in which has a set point of 14.8, although it is still doing 15v. I even tried putting the sense wire at the alternator output just to ensure voltage drop wasn't an issue with no luck so it's back wired up normally.

In terms of the technical bulletin, was there anything that could be done? Is there a way of finding that bulletin just for interest's sake?

If it's not liking the voltage spikes I'll have to go to a different amp, maybe the 2 boston GT22's a had in place before
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kg1961
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Re: SD800.4 question

Post by kg1961 »

gfunk_nz wrote:The sundown is a SAZ2500, I've removed the self exciting regulator a put a 3 wire one in which has a set point of 14.8, although it is still doing 15v. I even tried putting the sense wire at the alternator output just to ensure voltage drop wasn't an issue with no luck so it's back wired up normally.

In terms of the technical bulletin, was there anything that could be done? Is there a way of finding that bulletin just for interest's sake?

If it's not liking the voltage spikes I'll have to go to a different amp, maybe the 2 boston GT22's a had in place before

very odd
i also remember reading something like that. I have ba gt amps I just posted for sale cheap if you need gt22 and gt40
most of my gear is gone :liar:
2020 honda accord sport
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dwnrodeo
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Re: SD800.4 question

Post by dwnrodeo »

Added
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PG SD Amplifier Tech Bulletin.pdf
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XS2300, XS2500, XS2300, X200.4, X100.2, Ti21000.4, Roadster 66

I'm gonna become a civil engineer. I'm gonna design septic tanks for playgrounds. Little kids can take shits! You idiot, what the hell do you do?
gfunk_nz
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Re: SD800.4 question

Post by gfunk_nz »

Thank you for the bulletin, I see it doesn't even mention the 800.4 so I'm not sure if it was pre or post the bulletin, but even 15.8 is a low figure I would have thought.

As nice as it would be to get the GT40 the shipping would probably be a bit much, but thank you for the offer. I've still got two GT22's sitting on the amp rack I pulled from the car, one for tweeters, the other for the mids.
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