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940 original radio does nothing - replace or fix?

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Old May 10th, 2020, 12:37   #11
bob12
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Assuming you have an external amp fitted in the usual place up amongst the wiring behind the dash on a strength strut above you right knee you will have to by pass that as all the speakers wires come from that to the various speakers

What you wanted was an Autoleads PC2-19-4 Car Stereo Harmess with amplifier baypass lead for 740/760/940/960/850 etc. You will find them on eBay etc and, can view details on Autoleads website. It comes with all compatible plugs/sockets to connect to the existing loom plugs/sockets.

Bob.
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Old May 10th, 2020, 16:16   #12
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Originally Posted by mister grimsdale View Post
Quite by chance, I've been chasing a radio code recently too. There are various (mostly very old) posts about contacting the dealer or downloading software. Most of the links to software are now dead, but I found a couple which still worked. They set the anti-virus off; and when I ran them in a virtual machine they gave wrong answers anyway.

So having plenty of time on my hands just at the moment, I dug into the coding a bit. If you can be bothered to do a bit of light dismantling, you should be able to reconstruct the code from the block of diodes on the main circuit board (see pics)

To get to them you need to take the top cover off and remove the cassette deck -- disconnect the two electrical connectors and undo four screws at the corners and it can be eased out.

Read off the diodes, putting a 1 if there's a diode present and a 0 if there's no diode, in the order d10,d11,d12 d6,d7,d8 d2,d3,d4 d9,d5,d1. That gives you four groups of three. In the picture, for example, that's 011 110 011 101.

Convert each of the groups of three from binary to decimal; 4 x (first position) + 2 * (second) + (third). If a group comes out as 0, read it as 6; if a group comes out as 7, read it as 1. That gives you your 4-digit code. More difficult to describe than to do.

Caveat: this was for a CR-905. Yours is a CR-906 but I bet it's the same. The above worked for a CR-706 that I was able to use for an additional check.

Incidentally, If any one has the CD-changer that went with the CR-905 going spare, I'd be interested.

Phil
Brilliant info, thanks - incidentally the link below indicates you are right and that the CR-906 uses the same system:

https://www.dndservices.co.uk/COD/?T...odel_name=7494

Re the external amp and sound quality the link below suggests the CR-906 has a built in amplifier - so hopefully the speaker wiring is straight forward. I haven't looked for an external amplifier yet - seems likely that there will not be one in my car.

https://www.volvoforums.org.uk/showt...t=99183&page=2

Also indicates that it's got a fairly healthy power output. Given this and the features it includes I'd expect it to sound at least OK.

Plan a is to try to get a code number based on the VIN. If that fails I'll have a look at the diodes. If I can't get it working I'll look at fitting a replacement.
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Old May 10th, 2020, 16:34   #13
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Also indicates that it's got a fairly healthy power output. Given this and the features it includes I'd expect it to sound at least OK.
If you think 4x 20W RMS is a healthy output, i hope you're not disappointed! Also bear in mind the door speakers fail, the cones split and sometimes disintegrate completely.

Depending on your excat door cards, usually 13cm (5.25") coaxial or triaxial speakers will fit straight in but they need a slim voice coil and magnet so as they avoid the window mechanism. You can buy adaptor rings to mount them or even spacers (about twice the price of the adaptors) to make life easier as they have an odd screw pattern :

https://www.ebay.co.uk/itm/VOLVO-740...5/290388292676

Hope you can find something to suit!
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Old May 10th, 2020, 17:20   #14
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Originally Posted by Laird Scooby View Post
If you think 4x 20W RMS is a healthy output, i hope you're not disappointed! Also bear in mind the door speakers fail, the cones split and sometimes disintegrate completely.

Depending on your excat door cards, usually 13cm (5.25") coaxial or triaxial speakers will fit straight in but they need a slim voice coil and magnet so as they avoid the window mechanism. You can buy adaptor rings to mount them or even spacers (about twice the price of the adaptors) to make life easier as they have an odd screw pattern :

https://www.ebay.co.uk/itm/VOLVO-740...5/290388292676

Hope you can find something to suit!
It's the not the cone itself that splits but rather the foam surround - the foam degrades over time and eventually falls apart. It's actually possible to replace it but given how cheap car speakers are probably not worth the effort. Mine seem in pretty good order at the moment so I'll probably keep them until they fall apart.

With my track record for swapping cars it's probably best not to plough too much money or time into improvements. Main thing is to keep it on the road. Would be nice to have some tunes though.

20 watts is plenty for me, thanks. My comment was that it was a healthy output by the standards of the day. Today perhaps you might expect more like 50 watts but in practice there's not loads in it - 100 watts is only twice as loud as 10 watts.
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Old May 10th, 2020, 21:18   #15
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It's the not the cone itself that splits but rather the foam surround - the foam degrades over time and eventually falls apart. It's actually possible to replace it but given how cheap car speakers are probably not worth the effort. Mine seem in pretty good order at the moment so I'll probably keep them until they fall apart.

With my track record for swapping cars it's probably best not to plough too much money or time into improvements. Main thing is to keep it on the road. Would be nice to have some tunes though.

20 watts is plenty for me, thanks. My comment was that it was a healthy output by the standards of the day. Today perhaps you might expect more like 50 watts but in practice there's not loads in it - 100 watts is only twice as loud as 10 watts.
Foam surround? Crikey, you're an optimist on the quiet aren't you!

Most of the OE speakers i've seen in Volvos still have the (much older design) paper support so any rot in the paper cone also happens to the support too. It's possible the later 9xx models have foam but i don't think i've seen any.

While what you say about 100 Vs 10W is correct in theory, in practice with todays levels of traffic and other background noise, what would have been perfectly acceptable 30 +/-5 years ago isn't necessarily acceptable now. Also factor in that as you turn the volume up so you can still hear your music above the higher ambient noise levels, so the THD (Total Harmonic Distortion for those not familiar) rises exponentially.

To that end, in my other beast i have an amp in the back to boost the OE spec from 25W RMS per channel to 75W RMS per channel, with the fronts still on the original outputs. This means i can get it louder without hitting THD too soon. This is relevant as i've installed the same head unit and 6 disc changer in my 760 and that really needs an amplifier in it too.

I have aftermarket speakers in my other car front and rear and aftermarket speakers in the front doors of the Volvo. For some reason the rears seem to have fared better over the years than the fronts that came out with no cones or supports left!
The Volvo and my other car front speakers are the same, triaxial 13cm, 80W RMS jobbbies (cheap make but do the job) and the rears in my other car are 6.5" (soon to hopefully be changed for 8") triaxial beasts.

With that said, i recently upgraded/updated the head unit in my other beast to a modern one that as well as having built in BlueTooth (and a hands free phone mic) boasts 45W x 4 but a bit of investigation suggests that is the oft-misquoted "music power" and the real output is 25W RMS per channel as it's about the same sound output as the original, just a bit clearer with less THD when turned up.

The BT capability means i can store music on the SD card in my phone so i don't need to keep changing CDs in the 6-disc changer, any calls coming in are handsfree and played through the car speakers and if i happen to be using the sat-nag on the phone, any instructions from that come over the car speakers as well.
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Old May 10th, 2020, 21:55   #16
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Foam surround? Crikey, you're an optimist on the quiet aren't you!

Most of the OE speakers i've seen in Volvos still have the (much older design) paper support so any rot in the paper cone also happens to the support too. It's possible the later 9xx models have foam but i don't think i've seen any.
Optimist? I looked under the grille. Besides, a foam surround is hardly a feature of high end audio. They're found on all sorts of stuff from the very cheap to the pretty decent.

In the front at least, my car is fitted with a pair of 6" paper cone drivers with foam surrounds and a little mylar tweeter in the middle. Riveted in place so obviously OE.

I haven't looked in the back, but there seem to be some tweeters or something in the dash. Overall setup looks not too bad to me. Is a later car.

Last edited by marm; May 10th, 2020 at 21:58.
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Old May 10th, 2020, 22:59   #17
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Optimist? I looked under the grille. Besides, a foam surround is hardly a feature of high end audio. They're found on all sorts of stuff from the very cheap to the pretty decent.

In the front at least, my car is fitted with a pair of 6" paper cone drivers with foam surrounds and a little mylar tweeter in the middle. Riveted in place so obviously OE.

I haven't looked in the back, but there seem to be some tweeters or something in the dash. Overall setup looks not too bad to me. Is a later car.
I just had a look at a pair of speakers i removed from my 760, strangely they had intact cones and supports but i know the drive coil on at least one is FUBAR.
At first glance i thought i was wrong and that they had foam supports. Closer inspection revealed it was an impreganted material, perhaps polyurethane or similar. Given the state of the others i removed with paper supports, i suspect these were renewed by Volvo at some point in the cars life.

Thing is, the OE speakers were pretty low level and barely capable when new. I understand the cars under Fords complete ownership (1999 on) had much better audio systems built to a quality level rather than a cost. Many were Sony with 6 disc CD changers built in to double DIN head units. I think also better speakers were fitted.
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Old May 11th, 2020, 23:46   #18
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Or replace it with a modern one as the originals are rubbish. They really are. I replaced mine (which was the top of the range one with CD changer etc) with a cheap modern one and the new one is miles better.
Why are they rubbish? If i'm using a decent HU (SR-701) with an external amp and a BT module then how is it inferior to modern decks that you by at your local department store? Okay, ergonomics is an issue as you cannot control everything from your phone but classic periood correct looks count for something as well!
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Old May 12th, 2020, 01:46   #19
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Why are they rubbish? If i'm using a decent HU (SR-701) with an external amp and a BT module then how is it inferior to modern decks that you by at your local department store? Okay, ergonomics is an issue as you cannot control everything from your phone but classic periood correct looks count for something as well!
While i agree with the general sentiment of what you've said, try replacning your ancient head unit with a modern one of a similar output spec. Then see if you still maintain the old ones are just as good, even with the BT-FM transmitter etc and setting ergonmomics aside.

I can say this hand on heart as it's exactly what i've recently done and i was very glad i did! Vast improvement in sound quality, clarity, radio reception (despite the original being tuned to the antenna system built into the car with diplexed FM and AM outputs from the antenna to the head unit and different front ends in the OE unit to maximise the advantage and only using the FM antenna for everything on the new unit) and general reproduction.

Also as the case was for my original sound system, the fact it was getting older and components were becoming out of tolerance (both mechanically and electrically), the quality of the output had dropped, as had the functionality of it.
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Old May 13th, 2020, 19:58   #20
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Right, well, I got the code by emailing the guy in the link I posted earlier...top stuff!

...code worked

...but stereo didn't - display and buttons functioned but no sound from the radio and tapes not turning.

I'm going to fit an aftermarket unit. Got a few to choose from. Fingers crossed that the ebay adapter works - when it finally arrives.

Fingers crossed it should be straight forward as I don't think I have an external amp.

No rush to sort it as I can't drive anywhere anyway...
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