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FOUNDING MEMBER
1995-2002 Range Rover P38A
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488 Posts
Discussion Starter #1
Rangie has just returned from the Indy with the ABS/Traction problem solved - yay - but I’m still awaiting the description of what was wrong and what the fix was. However, I digress. It has returned complete with an odd radio problem.

The radio will switch on and all the controls operate and it will tune in correctly (RDS descriptions appear) and operate the CD player etc., etc but there is no sound from the speakers except a very low sound from the Sub-woofer as if it is getting a very, very low signal. Suddenly the system will burst into life and everything is hunky-dory for a minute or two when the sound will distort momentarily and then disappear with just the sub-woofer murmuring the correct tune/beat. The short phase of working can be when the radio is initially turned on or some minutes later - it seems completely random,

Is this likely to be the head unit or that pesky HK DSP amplifier in the back which is now made of unobtanium?
 

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LEGACY VENDOR
1995-2002 Range Rover P38A
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4,219 Posts
Out of interest which Indy was looking at the ABS/TC fault?

Regarding the radio issues - I don't want to say DSP amp - but unfortunately they seem to be the main cause of issues with the later audio system. If it were the head unit, I would expect either everything to drop out - sub included - OR on side - everything on the left or right to drop.

All is not lost as I know a guy who does a replacement board for the DSP amp with 4 normal door amps :p only a bit of soldering and basic wiring required...
 

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FOUNDING MEMBER
1995-2002 Range Rover P38A
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488 Posts
Discussion Starter #3
Marty,

The Indy who sorted the ABS/Traction issue (after much consternation) is http://Www.mjrolls.co.uk

i think they they had trouble as it was intermittent and kept coming up as no fault and then when they drove the vehicle the lights and warning message would pop on and then disappear when they got back to the shop to connect up to the diagnostics. But they got there eventually and I am waiting to hear exactly what they found/did.

Regarding the radio, I’ll pull the head unit this w/e and give it a good check over. If that checks out OK I may take advantage of the services of the guy you refer to if he’s willing. Have you a price for the replacement board? I might even sort out the couple of failed door locks I have replaced over the past years whilst I have the soldering iron out! Where do I get the microswitches?

The reason I suspect the HU is that I thought (but may be mistaken) that the subwoofer HU signal does not go via the HK DSP amp but direct to the subwoofer amp and that signal is also dropping to a very, very low level when the problem occurs. I‘m half suspecting the HU pre-amp.
 

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LEGACY VENDOR
1995-2002 Range Rover P38A
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4,219 Posts
Hmm, not the same place as I have been dealing with awhile ago with one that was giving issues...

Let me know how the head unit surgery goes... I'd be interested to know if there are any normal failure points around the later HUs!

DSP replacement board is £100 plus postage, and comes with custom loom, and instructions for fitting. I actually have one made up and on the shelf for a change! But I'm away a lot until December now working, so not about to post anything out (if required) until then.

Door latches - I use microswitches from RS components - DC3C-A1AA or equivalent is the part number if I remember correctly. The issue on the later latches is that the switches are all moulded together in a block and not available to buy like that. On latches that I rebuild, I drill a couple of extra holes in the casing and motor board and use M2.5 rod to pin the new switches in place so that the activate properly.

Regarding the sub - yes, the subwoofer level does go into/out of the DSP amplifier. I believe that even though it's a separate output from the head unit, the level is adjusted/mixed in the DSP settings in the DSP amp itself, and then spat back out to the sub amp. One of the modifications in the wiring for the amp board is to snip these wires going into/out of the connector and join them in line so that the HU controls it directly (When the HU doesn't detect the DSP amp connected, it changes mode so it then does all the audio levels/mixing/fade/balance etc internally, rather than the DSP amp doing it).

Hope this helps, and let me know what you find!

Marty
 

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FOUNDING MEMBER
1995-2002 Range Rover P38A
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488 Posts
Discussion Starter #5
Marty,

Thanks for the response and door lock micro switch instructions.

Regarding the radio, I extracted the HU and took the Nokia Hands Free system I have installed out of the circuit. No difference.

I then tested the HU on the bench and all seemed to work so I reconnectrd it to the vehicle carefully checking all connections and the fuse on the back of the unit and fired up the system. It worked and continued to work flawlessly for 15 minutes so I reinstalled everything assuming a loose connection had been sorted. With everything back in place I fired up the system again and it worked flawlessly, again, for 15 minutes.

The next time I fired up the vehicle the radio came on and worked . . . . . . for two minutes then failed. Arrrgghh,

That’s as far as I got as I thought it was fixed so I’m no further forward. However, what I did notice was that when the failure occurs the settings - bass, subwoofer, balance, fade, DSP setting - all revert to default values. Are these held in the HU or the DSP amp as this could point to the source of failure?

I have persuaded a friend to loan me his HU so I can test the system with it which will be next w/e activity. I hope my system doesn’t blow his HU!!!!
 

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FOUNDING MEMBER
1995-2002 Range Rover P38A
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488 Posts
Discussion Starter #6
There's good news and bad news.

The bad news first. Good head unit inserted into system at beginning of the week and . . . . . . . no difference. Obvously the DSP amp is dying. Argghhh.

The good news. Managed to pick up a used DSP amp that was expensive but not ruinously so! Installed into the system this morning and its all up and running nicely. Yay!

I just wonder how long this one will last before it dies of old age!
 

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LEGACY VENDOR
1995-2002 Range Rover P38A
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4,219 Posts
Good to hear you have a working solution at the moment, and was able to find a working DSP amp!!!
 
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