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1995-2002 Range Rover P38A
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Discussion Starter #1
My subwoofer stopped working. On investigation it was clear that the subwoofer speakers were in excellent condition and were trying their best but movement was minimal. Obviously the amplifier had 'gone west'. A replacement amplifier was obtained via flea bay, fitted and all is well . . . . . . for now!

This is the failed amplifier that was removed.

IMG_0001.JPG

As can be seen this also looks to be in excellent condition. However, these amps are screwed directly to the bottom of the speakers - no wonder they fail, the vibration environment must be . . . err . . . substantial.

Seems such a shame to just junk it as the failure is probably just a single component. Anyone in the UK able to diagnose and repair this?
 

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1995-2002 Range Rover P38A
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Um, no!
Many have tried, no-one has yet achieved it. There are always rumours of "a guy in Europe" who "used to do it".
Loads on this site about work arounds/ substitutes for failed amps. Have a dig through Search using "DSP amplifier failure" or similar
 

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1995-2002 Range Rover P38A
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That isn't the unrepairable DSP amp that is a complete mystery to everyone except maybe the guy that originally designed it but a pretty straightforward analogue amp. Should be possible for just about any audio engineer to sort it.
 

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The DSP am is a much larger and complex beast. It mounts behind an additional trim panel behind the sub. What is pictured above is a standard subwoofer internal amp.
 

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The DSP ones are probably not fixable because the DSP chip is an "epoxy blob" on the board. Annoying, because I change 144-pin monsters on PCBs all the time. There's a stock fault in a particular Korg synth that involves replacing just such a 144-pin DSP chip, which is a cheap off-the-shelf part.

That amp has pretty much nothing on it - a couple of bridged power amps (one for each speaker) and a preamp (the little surface-mount bits on the right. If you were closer I'd take a crack at it. It's a far bigger amp than the one strapped to the subwoofer in my '98, which resembles one of the door amp units.
 

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I know somebody on here fixed one. It was a simple capacitor or something he metered it and was able to find the bad part. He desolated it and replaced with a new one. I'll dig in my file folder to see if I can find it. Oh and I have talked to Alpine and they can fix the DSP amp for $275.00. I'll look for that email.
 

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You could probably build a modern replacement easily enough, with more efficient amps and a better DSP. The trick would be working out what the head unit says to the DSP to control the settings.
 

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I know somebody on here fixed one. It was a simple capacitor or something he metered it and was able to find the bad part. He desolated it and replaced with a new one. I'll dig in my file folder to see if I can find it. Oh and I have talked to Alpine and they can fix the DSP amp for $275.00. I'll look for that email.
I think if alpine could repair the dsp amps they'd be extremely busy, a secondhand one for your ( with sat nav) if you can find is double if not more than they've quoted you.
When I got my present car the amp had gone, I ended up getting from the states, cost $450 plus postage, but it was the only one available at the time
 

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I am down in W.Sussex and repair quite a lot of car audio,as Gordonjcp says a lot of BLOB chips on Becker/Harman gear (BM54 etc.)Some times lucky,sometimes not.Must admit not seen one of these before.
 

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1995-2002 Range Rover P38A
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Discussion Starter #10
Thanks for the replies. In my school and uni days I had access to signal generators and oscilloscopes so could easily test out these things myself. It actually doesn't look too complicated - two identical channels, one per speaker and just low pass filter and a couple of amps. It does have a rather mahoosive heat sink though!

The problem is that both channels are not working so I'll have to trace the common circuitry. When I get some time I'll break it down and see if there is anything obvious that a standard multi meter can diagnose. You never know, it might be one easily replaceable component gone AWOL or even just a dry joint - nothing to be lost in trying.

If I do get it going I think I'll extend the speaker wires and sort out a mounting external to the subwoofer back box so it doesn't get vibrated to death.
 

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Upto you, but the subs come up cheap enough all the time, I was unlucky enough to have the sub amp and dsp go pop at the same time,,
 
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