V70 Stereo/DVD: HU-850 Findings

[Smashed Monkey]

I have been suffering with what seems like a common problem on these units. From switch on, no sound other than a regular clicking noise that comes though all the speakers. Then occasional blasts of full volume sound from the radio.

I cut my teeth as an electronics engineer, so I had a hunch that the problem would be one of 2 things. Both being thermally influenced. The first thought was either dry joints or micro cracking on the PCB, then secondly, dried up aluminium electrolytic SMD capacitors or semiconductor instability.

I removed the unit from the car and stripped it down to the main board and the connection interface panel. I noticed immediately that there was a brown area on the board near the tuner pack and beneath some surface mounted regulators

http://www.volvoforums.org.uk/attach...1&d=1387797602

On the top side it looks like this, with some likely candidates for replacement in that cluster of aluminium electrolytic SMD capacitors. I used to have fun and games with these things in Sony camcorders a few years back. I just replace them on spec' whenever I see them near to hot components.

http://www.volvoforums.org.uk/attach...1&d=1387797496

I carefully assembled the main board and connection riser board as well as the front panel. I took it to the car and plugged in the multiway connector and the DIN connector and aerial. (You don't need the tone controls or CD mechs to make the unit work. When I switched on, I got full normal operation, volume up and down and station change all working. I flexed the main board near the Tuner/IF can (standing up at the side). It all went quiet with a feint clicking. It seemed really sensitive to any movement in that area (where the heat has discoloured the PCB.

Back on the bench, I found a dry joint on the pair of regulators that are part of a few power components mounted on the edge of the main board that use the metalwork of the case as a heat-sink. I could see the tell-tale crack around the solder pad. I soldered these up and then went over the whole board resoldering the most likely joints and all the main connector strips where possible (you need a fine tipped iron with temperature control preferrably). I have a midget Weller Pyropen which is great for this.

http://www.volvoforums.org.uk/attach...1&d=1387797602

I have got good results initially with this, but I need to test it further to establish whether this is a good fix. There are a couple of postage stamp ICs under a soldered shield. These have tiny soldered legs, and it is possible that there may be some dry ones there too. I will try and go over these too, but need to be really quick with the iron to avoid damaging the very small and fragile PCB tracks.

I will update this thread when I have fully completed the repairs. I have seen some of the quotes on the Net, for getting these things replaced. They are pretty average bits of kit, and I was stunned to see prices of between £400 to £600 being bandied about. These things are just not worth that sort of money. To repair as I am doing takes a bit of experience with electronics and the right tools for the job. It is within the capabilities of anyone who is confident to tackle these things, and is dextrous enough with a soldering iron. I am fortunate in that area. I would recommend that anyone who has problems with this or similar models, and who does not possess the necessary skills should seek a professional or competent repairer, or risk damaging the unit beyond all hope of repair.

[Clan]

excellent and so satisfying to fix it .
Central Services in Ipswich are the people to repair these , no need to fork out £600 for an exchange unit , Volvo exchange radios were £120 before ford came along !
Central Services have the most spares and experience of anyone in the country of working on these units .

[Smashed Monkey]

Well, I have been over all the components except for the aluminium caps on the main board. I had none of the correct value in my spares stock. I have improved the situation quite a bit, where the radio or CD plays for quite a time after switching on, but sadly, after about 10 minutes, a crack and then silence. So still not resolved. I suspect the capacitors, but probably a semi-conductor going down, and the worst of it is that now in my 50s, I can't see the sodding little things - even with my glasses on and a magnifier!

I have decided that I am on a fool's errand with this. I don't think it is work the bother as I really want to use the amplifier to allow me to play the music playlist on my phone. I don't have the time needed to work on with this and my wife is fed up with the piles of screws and bits of stereo littering the dining table.

I would love to know what the fault was, but I don't suppose anyone will be able - or more accurately - prepared to tell me as it would potentially kill off a nice little income stream from the repair of these rather disappointingly unreliable units.

I'm going to junk this unit and buy myself a more up-to-date unit which will support Bluetooth and USB playback as well as support my Samsung Ativ-S Windows 8 Phone. (I know, now I am really asking...)

It would be good to know if there is a head unit (double or single DIN) that would work well in the Volvo. Also a decent fascia adaptor so that I don't have to butcher the original console front?

[nickbw898]

There is a chap in York, also a very experienced electronics engineer, who does this and similar, probably even more micro-miniature work (not on Volvo radios, as far as I know). He was so disgusted with his Apple NAS server/ rooter (Time Capsule) going down after barely a year that he disassembled it, discovered which SMD components had failed (due to overheating) and that the 'cooling fan' was only designed to come on once the unit was unduly stressed and experiencing very high temps. He modified all this, including the case design to enable the fan to run at half speed continuously and cut a large port in the base for external air to be drawn in. Even apple conceded his modification was a significant improvement! He provides this repair service for other "victims", and it takes him barely a week-end at a moderate cost of £100 -200. How he sees what he is doing God knows. He must have a hugely powerful microscope!

[outnumbered]

i have fitted this.
http://www.ebay.co.uk/itm/1111828489...84.m1439.l2649


with this
http://www.ebay.co.uk/itm/1505645645...84.m1436.l2649
you lose the steering wheel controls.
mike

[outnumbered]

http://forums.t5d5.org/topic/25240-double-din/

[lenjo]

Originally Posted by Smashed Monkey

I have been suffering with what seems like a common problem on these units. From switch on, no sound other than a regular clicking noise that comes though all the speakers. Then occasional blasts of full volume sound from the radio.

I cut my teeth as an electronics engineer, so I had a hunch that the problem would be one of 2 things. Both being thermally influenced. The first thought was either dry joints or micro cracking on the PCB, then secondly, dried up aluminium electrolytic SMD capacitors or semiconductor instability.

I removed the unit from the car and stripped it down to the main board and the connection interface panel. I noticed immediately that there was a brown area on the board near the tuner pack and beneath some surface mounted regulators

http://www.volvoforums.org.uk/attach...1&d=1387797602

On the top side it looks like this, with some likely candidates for replacement in that cluster of aluminium electrolytic SMD capacitors. I used to have fun and games with these things in Sony camcorders a few years back. I just replace them on spec' whenever I see them near to hot components.

http://www.volvoforums.org.uk/attach...1&d=1387797496

I carefully assembled the main board and connection riser board as well as the front panel. I took it to the car and plugged in the multiway connector and the DIN connector and aerial. (You don't need the tone controls or CD mechs to make the unit work. When I switched on, I got full normal operation, volume up and down and station change all working. I flexed the main board near the Tuner/IF can (standing up at the side). It all went quiet with a feint clicking. It seemed really sensitive to any movement in that area (where the heat has discoloured the PCB.

Back on the bench, I found a dry joint on the pair of regulators that are part of a few power components mounted on the edge of the main board that use the metalwork of the case as a heat-sink. I could see the tell-tale crack around the solder pad. I soldered these up and then went over the whole board resoldering the most likely joints and all the main connector strips where possible (you need a fine tipped iron with temperature control preferrably). I have a midget Weller Pyropen which is great for this.

http://www.volvoforums.org.uk/attach...1&d=1387797602

I have got good results initially with this, but I need to test it further to establish whether this is a good fix. There are a couple of postage stamp ICs under a soldered shield. These have tiny soldered legs, and it is possible that there may be some dry ones there too. I will try and go over these too, but need to be really quick with the iron to avoid damaging the very small and fragile PCB tracks.

I will update this thread when I have fully completed the repairs. I have seen some of the quotes on the Net, for getting these things replaced. They are pretty average bits of kit, and I was stunned to see prices of between £400 to £600 being bandied about. These things are just not worth that sort of money. To repair as I am doing takes a bit of experience with electronics and the right tools for the job. It is within the capabilities of anyone who is confident to tackle these things, and is dextrous enough with a soldering iron. I am fortunate in that area. I would recommend that anyone who has problems with this or similar models, and who does not possess the necessary skills should seek a professional or competent repairer, or risk damaging the unit beyond all hope of repair.

Extremely interesting article. My HU 850 has recently failed with a loud hum/buzz but that noise appears to come from the 'head' unit. I did think that it was the under-seat amp. but I was wrong. I will investigate further when I have time. I phoned this Ipswich bunch and got someone called 'David' who couldn't answer my question about this radio. I will say that when I spoke to Marcel last year about a problem on my old radio in my older car, a 240, which is a CR705, I was able to pass on a message regarding faults I had cured on that radio, concerning dry joints and cracks in the PCB. I had a pleasant conversation with Marcel. I was surprised how different the conversation was with this David. He was giving me quotes of up to £300 to repair this radio. I am not prepared to pay through the nose for a repair which I am perfectly capable of fixing myself, even if I have to reverse engineer the whole system to do so. It may well be that I'll need to reverse engineer part of the system to effect that repair, and when I do, I may well come out of retirement and advertise a more affordable repair service for the many people who seem to experiencing faults on what appears to be a shoddy radio, (I've no doubt it's American in origin).

[Jonny5isalive]

Great post. Seems like this particular HU is the weakest of the bunch. Very disappointing as it's meant to be the top model. I just wish I was competent with electronics myself and I'd have had a go with my 850 unit, but I've a mechanical background.

Hopefully the £80 repalcement that's on its way will be just the ticket. Anybody interested in my old one for spares? Cd mechanism seems fine and all buttons work.

[Jonny5isalive]

Originally Posted by lenjo

Extremely interesting article. My HU 850 has recently failed with a loud hum/buzz but that noise appears to come from the 'head' unit. I did think that it was the under-seat amp. but I was wrong. I will investigate further when I have time. I phoned this Ipswich bunch and got someone called 'David' who couldn't answer my question about this radio. I will say that when I spoke to Marcel last year about a problem on my old radio in my older car, a 240, which is a CR705, I was able to pass on a message regarding faults I had cured on that radio, concerning dry joints and cracks in the PCB. I had a pleasant conversation with Marcel. I was surprised how different the conversation was with this David. He was giving me quotes of up to £300 to repair this radio. I am not prepared to pay through the nose for a repair which I am perfectly capable of fixing myself, even if I have to reverse engineer the whole system to do so. It may well be that I'll need to reverse engineer part of the system to effect that repair, and when I do, I may well come out of retirement and advertise a more affordable repair service for the many people who seem to experiencing faults on what appears to be a shoddy radio, (I've no doubt it's American in origin).

The replacement unit arrived today and it has Mitsubishi Electric on the stickers, I'm assuming they all are made by them, but don't know for sure. Expected more from a top electrical company. Good news is that the radio works superbly. I've never heard such an awesome sounding factory fitted system. Bad news is that the CD player just shows ERROR on the display and the unit has things rattling around in it... Grrr! Contacted salvage yard.

[Symes]

Thats bad news, I don't know if there are any on the HU850 but some CD/DVD manufacturers used to install 'shipping' screws to stop the mechanism from moving during transport, it might be worth trying to identify any suitable looking holes and advise the breakers so the next one doesn't end up the same way.

If you're stuck/adventurous/brave you might look to transplant your original CD mechanism into the replacement HU, I think there's been a post on here doing something similar.

If you're going to chuck your old HU at the hopefully (positive) resolution of fully work radio and CD I might be interested in having it off you for spares, particulary the buttons!

Symes