92 Volvo 240 factory head unit low volume left channel

Two_Four_Zero

Hi Gurus,

I have an issue with a 92 Volvo 240 factory radio.

The left channel has low volume.

I checked the balance on the head unit.

I swapped speakers left to right and it's definitely the head unit.

The head uniit also has an odd DIN plug in addition to the main harness and antenna.

Thanks.

carnut222

Pretty sure somebody like Craig Rasmussen in the South Australian club could repair it. He also converts them to bluetooth as well. His details are in the classified ads section of Rolling magazine or I can pass them on if you don't have them. Lemme know/

paul0075

Could be a dead capacitor on the board inside the head unit, it's at that age where caps tend to self-terminate.

Major Ledfoot

Craig Rasmussen does excellent work. Highly recommended.

Looks like a Mitsubishi manufactured unit going by the label.

Dead cap is possible, dry solder joint is also possible. Dead audio output IC is likely.

paul0075

If you do find it is a dead IC, see if Worldwide Electronics in Bentley, WA has a replacement, they have a few harder to get ICs.

Two_Four_Zero

I did a little more digging, and it looks like this headunit has is connected to an external amp by a single circular DIN plug cable. The amp is mounted down behind the lower pocket.

Is the issue more likely to be the Amp?

I see there is a 2 cable bypass harness by Metra. Has anyone found a local supplier for this, aside from Ebay or Amazon?

https://metra-oreilly.com/product/70-1120

jamesinc

Most likely it will be crud interfering with the contacts in the dials. They are analogue, I don't know the exact circuitry but essentially the audio output is running through the dials before going to the amp circuit. Do you hear scratchy sounds when you turn the dials?

I've had good results by taking the enclosure off and blasting everything with compressed air.

Brad

I had the same problem with the factory CR-728 head unit in my 940 a few years ago. The cause was a cracked solder joint on the circuit board to the plug going to the graphic equalizer. Resoldering that fixed the problem. Could be a similar problem to the amp plug maybe.

Ex850R

De-Oxit or the like in the knob pots , squirt the boards and blow out.

Major Ledfoot

I got a locally-made harness that was supposed to fit an SC-816 head unit (totally different radio to yours though) and it didn't fit, so I don't have a lot of faith in the locally-available stuff.

More testing would be needed to determine if the radio itself is going low output on left channel, or if the amp is going low output on left channel, or if there's a high resistance connection between the amp and the radio on the left channel wiring.

Do you have a spare HU you can plug into the amp to prove the amp is okay?

Also, does the 5-pin DIN connector on the radio (where the cable to the amp plugs in) appear to be heat damaged?

Two_Four_Zero

Major Ledfoot
I got a locally-made harness that was supposed to fit an SC-816 head unit (totally different radio to yours though) and it didn't fit, so I don't have a lot of faith in the locally-available stuff.
More testing would be needed to determine if the radio itself is going low output on left channel, or if the amp is going low output on left channel, or if there's a high resistance connection between the amp and the radio on the left channel wiring.
Do you have a spare HU you can plug into the amp to prove the amp is okay?
Also, does the 5-pin DIN connector on the radio (where the cable to the amp plugs in) appear to be heat damaged?

Further investigation is on the cards. Inclement weather has dampened (pun intended) my deisre to dive into it any deeper.

We move house in a couple of weeks, and I have 2 weeks of painting in front of me, so this will need to take a bit of a back seat for now.

I ordered one of these, so if youre a Volvo head unit purist, look away.

https://www.ebay.com.au/itm/204074212263

Its a single din unit with CARPLAY and ADROID AUTO support. I bench tested it and connectivity to the phone works well.

For $99 delivered it was worth the risk. I just need an RHD single din fascia.

carnut222

I have spare amp(s) if you want to test that theory. Happy to post one to U for the cost of postage.

Two_Four_Zero

A quick thanks to all the replies and advice.

Its nice to be back and see nothing has changed here.

Photos of the unicorn to come :)

Ex850R

Two_Four_Zero
https://ozvolvo.org/discussion/comment/211353#Comment_211353
Further investigation is on the cards. Inclement weather has dampened (pun intended) my deisre to dive into it any deeper.
We move house in a couple of weeks, and I have 2 weeks of painting in front of me, so this will need to take a bit of a back seat for now.
I ordered one of these, so if youre a Volvo head unit purist, look away.
https://www.ebay.com.au/itm/204074212263
Its a single din unit with CARPLAY and ADROID AUTO support. I bench tested it and connectivity to the phone works well.
For $99 delivered it was worth the risk. I just need an RHD single din fascia.

That's brilliant!

I was looking at older Alpine or Pioneer , DAB and extra inputs preferred. This could be good.