OE Radio help.

[swedish brick]

Just after some help.
I’ve got an 88 GLE 740 estate with a CR702 radio cassette player. As long as I’ve owned this car it has never worked.

Today I’ve had a closer look at it, if you turn the unit on and enter the code it accepts it and the display works. The electric aerial also turns on and goes up. You can also cycle through pre-sets and use the seek button to change channels... the head unit itself appears to be working...

...but nothing is coming out the speakers! Three of the speakers are completely silent. But the drivers door one crackles and gets interference. This randomly comes and goes though. Sometimes even changing radio channels makes it stop or start.

I’ve dropped the lower dash plastic cover out to have a look behind it as I’ve heard there’s sometimes an amp behind here. Maybe that could be the problem.
There appears to be nothing behind here apart from wires and an old aftermarket alarm module which is now disconnected.

Any ideas!? I’d like to keep everything factory if I can. I’ve got no idea when it comes to radios and amps etc so I’m a bit stumped!

[swedish brick]

https://www.volvoforums.org.uk/attac...1&d=1571492812

Here’s a pic of the underside of the dash where, I’m told, the amp usually is. I don’t know what it’s supposed to even look like or why it’s necessary.

[bob12]

This is what you are looking for (see below - ignore the ignition switch also in the pic!!) .

The radio amp is located behind the dash above the driver's right knee (UK). It is attached to a metal strength strut.

Remove the under-dash trim to see/find it. The pre-amp audio feed wires come from the back of the CR-702 via the din socket. There is a much larger multi-pin plug on the amp which is the direct feed to the left and right hand door speakers.

If you have speakers on the dash they are feed direct from the back of the head unit via the wiring loom multi-plug.

Bob

[swedish brick]

Hmm, the plot thickens!

I’ve since managed to pull the radio out of the dash. I’m shocked the radio or heater surround didn’t break given the force I had to use but there you go!

https://www.volvoforums.org.uk/attac...1&d=1571497293

https://www.volvoforums.org.uk/attac...1&d=1571497293

https://www.volvoforums.org.uk/attac...1&d=1571497293

So with the radio out it shows the big multiplug connected but with a couple of unused wires/plugs. There’s a big plug inside the radio housing but that appears unused as there’s nothing for it to connect to on the radio. The aerial lead is present but the two din ports are both empty.
Port 2 is for an equaliser but isn’t used and has the correct blank plug fitted as per the manual.
Port 1 is for the amplifier. Seemingly not used either and there’s no lead for it either and no signs of any amplifier under the dash...

But, in the manual it says ‘extra amplifier’ which to me says the amplifier wasn’t standard fit?

[swedish brick]

Here’s a few better pics of what’s under the drivers side of the dash. I can’t see anything resembling what the amp is meant to look like? I can’t find any din cable for it either?

[bob12]

Tte radio just slides out if you release the two side clips!!

Your pics of under the dash seem to be looking straight in. You have to look upwards at a level with about the same or a bit higher than the headlight switch. You should be able to just make out the fins of the amp which is bolted (x2) on to the dash fascia metal support strength strut. It is not easy to see .... a mirror and a touch is of great help rather than breaking your back!

As far as I am aware the CR-702 as no inbuilt amp (like most head units of that era) and requires an amp. The pre-amp audio defo goes from that din plug on the radio to the other one on the amp not via the car's wiring loom multi-plug. It may be lurking further in amongst all the wiring behind the head unit.

I suppose you haven't got an aux/amp in the back of the car under one of the floor traps that the car may have been fitted with as an extra ... but I very much doubt it.

Bob

[bob12]

While I would still look for the amp, but if you are absolutely sure it is not there, maybe it isn't.

I have just looked at the Haynes wiring diagram for 1984-88 cars having now noted yours is 1988!! It doesn't feature an external amp (according to Haynes) but it does cover a wide age range!! Maybe your CR-702 is not the original head unit?

My 1990 745 originally had a CR -702 (now replaced by an all singing and dancing modern head unit ..... thank goodness) and, that had the external amp.

If you have Hayes check each of those coloured wires that come out of the multi-plug to see if they go directly to the speakers via the 'older' style 1988 loom, or if not post the colours and plug terminal numbers here and, I will have a look.

Sorry if I have misled you but, I can't believe a CR-702 doesn't require an external amp.

Bob

[swedish brick]

Originally Posted by bob12

Tre radio just slides out if you release the two side clips!!

Your pics of under the dash seem to be looking straight in. You have to look upwards at a level with about the same or a bit higher than the headlight switch. You should be able to just make out the fins of the amp which is bolted (x2) on to the dash fascia metal support strength strut. It is not easy to see .... a mirror and a touch is of great help rather than breaking your back!

As far as I am aware the CR-702 as no inbuilt amp (like most head units of that era) and requires an amp. The pre-amp audio defo goes from that din plug on the radio to the other one on the amp not via the car's wiring loom multi-plug. It may be lurking further in amongst all the wiring behind the head unit.

I suppose you haven't got an aux/amp in the back of the car under one of the floor traps that the car may have been fitted with as an extra ... but I very much doubt it.

Bob

Thanks for your help Bob! This is doing my head in!

The radio was a right pig to get out. The two tabs were tight and have actually bent my radio removal tools! Had use two little screwdrivers in the end, and a lot of pulling!

I’ve just had another look up under the dash...
Looking directly upwards I can see the underside of the dashboard, loads of wiring, ignition barrel, underside of instrument binnacle... there’s nothing whatsoever that resembles an amp. And no DIN lead for it either.
I’ve checked right down the hole the radio slots into for the DIN lead too and it’s not there!

Thing is, what do the cars speakers all connect to? Do they go back to the head unit or the amp?

And, is the amp supposed to be pretty much behind the headlight switch sort of area?

In the boot I’ve got the electric aerial in the little floor trap on passenger side, and a rectangular plastic cover with something behind it, but I can’t see that being the amp! Besides that, there’s no DIN cable there either!

I’ve got no idea what’s happened with this!

[swedish brick]

Originally Posted by bob12

While I would still look for the amp, but if you are absolutely sure it is not there, maybe it isn't.

I have just looked at the Haynes wiring diagram for 1984-88 cars having now noted yours is 1988!! It doesn't feature an external amp (according to Haynes) but it does cover a wide age range!! Maybe your CR-702 is not the original head unit?

My 1990 745 originally had a CR -702 (now replaced by an all singing and dancing modern head unit ..... thank goodness) and, that had the external amp.

If you have Hayes check each of those coloured wires that come out of the multi-plug to see if they go directly to the speakers via the 'older' style 1988 loom, or if not post the colours and plug terminal numbers here and, I will have a look.

Sorry if I have misled you but, I can't believe a CR-702 doesn't require an external amp.

Bob

Hmm, this seems plausible!
I’ll have a look tomorrow at the wire colours and compare to my Haynes wiring diagram.

Watch this space!

And, thanks again Bob!

[Laird Scooby]

Just a radical suggestion here - have you checked to make sure the speakers actually exist and if so, are intact? It's not unknown for a 30 year old car to have the voive coil but no cone left on the speakers!

The speaker grilles will either unscrw (screw in each corner) or if it's the later one, just pull off with long pegs holding it in.
Before you get too deep into whether you have an extra amp or not, check your speakers!

As for the CR-702 amp/no-amp debate, out of the three 740GLEs i've had, 1 x 87, 2 x88, the first (87) had the CR-702 plus amp, second had the CR-702 but no amp that i could see and the third had a dead CR-702 with amp. I suspect it was an option and the unit with the internal amp wasn't as powerful.
Even the external amp wasn't that powerful, if memory serves from when i checked mine, 25W RMS per channel split between the front and rear speakers for that channel.

If you have a look at this, it's one option from this seller on ebay :

https://www.ebay.co.uk/itm/Volvo-740...X/162552385453

Look at "Sellers other items" if that one doesn't take your fancy and enter 740 in the ebay search bar, it'll show you the various options they do for the 740 which are all plug'n'play and come with a face-plate adaptor, patch leads to bypass the amps etc.