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Heat issues with car head unit

Discussion in 'Troubleshooting and Repair' started by Skezza, May 7, 2015.

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  1. Skezza

    Skezza

    15
    0
    May 3, 2014
    Morning everyone,

    OK, so I've tried to use the HELP!! thread to write this, here goes:

    I've had several years of fairly hassle free performance from my aftermarket car head unit. It's unsurprisingly out of warranty but still works fine for the most part.

    This winter was particularly chilly which means I routinely had the heat on full, although not always blowing (sometimes just with the vents directed towards the driver, so heat is delivered through vents above the head unit). Anyway, it was around this time my head unit started playing up. With heat on full, after a while (non-deterministic amount of time), the audio would cut out and start crackling and popping in some cases cutting out completely. The software interface would remain perfectly functional though. This isn't exactly an exact science though, plenty of times it was fine with the heat on full. Maybe just 4 or 5 times over the course of winter. If I tapped the dash, the audio would cut back in and turning the heat down would seemingly fix the problem instantly. Going over rough roads or potholes would seemingly cause it to cut in and out rhythmically (is there a clue there?).

    My unit is out of warranty and the company are incredibly awkward about even talking to me about it. They've already suggested I buy a new one and they'd give me a discount as a goodwill gesture....exactly how this is a goodwill gesture I'm not sure really. Regardless, their newer models all have cooling fans on the back shell. Mine has mounting points for a cooling fan, and an open vent but no fan is actually present.

    I'm not the only one with this issue, there's a few on the internet complaining but I'm trying to find a decent solution.

    So, I've been told a solder reflow would likely fix this but I'm surprised that enough heat is generated by my fairly ordinary car heating system to melt solder!!! Another fix is apparently blu tacking a 2 pence piece on top of the DAC. I'm uncomfortable about doing this. For one, I don't know for sure that the failure is to do with the chip lifting up. Plus with it being not so consistent those who have done this might just be experiencing a placebo. The only other fix I can think is installing a cooling fan. Now, without taking the unit apart and looking, I don't know if there's even a socket on the board for a fan, however, it's entirely possible that there is because the motherboard is actually used across different brands and some of them have cooling fans.

    So, here are my questions:

    1. Would my car heaters really generate enough heat to melt solder?

    2. If so, I assume the DAC is some kind of integrated circuit, identifying it could be a nightmare. I can't just put pennies on every IC, it's surely adding extra stress to the board.

    3. Any other suggestions what it could be?

    4. If I add a fan on the back, would it really be able to compensate for the heat being delivered from the heaters? Surely it's just blowing hot air around, rather than away?

    Any other suggestions would be great. I'm tempted, tbh, to just sell this second hand with a defect, and buy a new one but if I can salvage this, I will.

    Cheers,
    Joe
     
  2. shrtrnd

    shrtrnd

    3,795
    503
    Jan 15, 2010
    NO, your heater wouldn't melt the solder.
    You DO have a heat issue, but it may be related to the age of the electronics, and the component's ability to operate in high heat.
    The first thing I'd do is examine the board, blow out any dust or dirt that may be trapping heat on the components on the board.
    Then I'd see if it's possible to reduce heat exposure. Can you somehow insulate the heat vents from the electronics? (Some type of insulation around the heat pipes, not the electronic unit)
    Electronics for automobiles are usually sealed to prevent exposure to dust and contaminants, so adding a fan would cool the electronics, but blow contaminants into the electronics.
    I'd look at trying to identify an add-on 'heat sink' if somebody makes one for the DAC (Digital to Analog Converter) IC to help dissipate heat, but the symptoms sound to me like
    the electronics have aged enough that heat is now becoming an issue.
    If you can't isolate the heat from the electronics externally, those are the only other options I can think of.
     
  3. Skezza

    Skezza

    15
    0
    May 3, 2014
    Hi,

    thank you very much for your reply. I really appreciate it. Firstly, thank you for clearing up the issue with the melting of the solder. I wasn't convinced myself that heat from my vents could really cause solder to melt. I think the logic behind that thinking is mainly coming from this idea that Xbox 360's were able to melt their own solder due to heat, however that was self generated heat, as opposed to heat being pumped in from the outside. I must stress, when the heaters are off or on cool, this doesn't happen, ever.

    The head unit is by no means new, but I wouldn't say it was that old either. I've certainly had ones that last longer, but I know this isn't an exact science and electronics do eventually wear out. I'm quite content in the fact I've probably had my moneys worth, but I love to tinker and fix.

    OK, I'll remove the head unit when I get chance and disassemble. See if there's any dust or contamination build up. The last time I opened it up, it was fairly clean, but that was almost 2 years ago. That's a good place to start.

    Regarding insulation from the vents, the vent channels run above the head unit and I believe are fairly well insulated anyway, so the head unit itself shouldn't be exposed to huge amounts of hot air blowing through. In reality, the only air that reaches the back of the head unit would be leaked air as far as I can tell. The head unit sits in a cradle which holds it into the dash. However, I can imagine those channels would get very hot and with the metal frame of the head unit, this may transfer inside. I've found it right hard to find any good photos of the dash on my car, or without a head unit, but here is a fairly decent photo of how it looks installed on Google:

    [​IMG]

    Above the head unit is a plastic piece which holds it in along with the cradle at the side which is all part of the car itself.

    [​IMG]

    Regarding the cooling fan. The intention was to have the fan blowing out of the unit, rather than sucking air in, effectively transferring heat away. There is about a 2 inch gap behind the unit before the dash buffer, so the heat would escape although possibly with nowhere to go, this wouldn't help too much. I've bought a fan anyway to test, it was only £1 shipped so that'll do.

    Great great great idea on the heat sinks though!! In reality, could I just add generic heat sinks to every IC chip? I'd use some arctic thermal compound to ensure heat transfer. Surely if I did that, I would subsequently find the one that is the DAC out of pure luck and that would really help with the heat issues. I've found a potential set of photos of the motherboard and peripheral boards but my heart sank. None of the chips seem to be labelled to suggest what they are, just have the name (i.e. Samsung, Hynix) and then nothing else:

    [​IMG]

    [​IMG]

    [​IMG]

    Can't lie, I'm pretty gutted about that :( :( :( :( :(
     
  4. quantumtangles

    quantumtangles

    152
    3
    Dec 19, 2012
    If you have a schematic, check the voltage rails.

    If the voltages are as they should be, some suggestions.

    1. The 10v 100uF Polymer electrolytic capacitors in the photos may be rated for 85 degrees C. Replacing them with 105C caps is tiresome but may help if hot air from the engine affected them. Well designed circuit boards tend to keep capacitors below areas where rising heat may affect them, but hot air from the engine moved the goalposts here.

    2. If the car heater did indeed behave like a hot air gun, it just might have fused one or two of the surface mount pins together (I have never seen this happen by accident but check out the first circuit board photo. The 3rd and 4th (upper) pins of the 16 pin IC looks as though they have been fused together (or at least the photo makes it appear so and I have assumed this is your actual circuit board which may not be so).

    I would break out my magnifying glass to check clearances on the surface mount pins. You have probably already done this and the photo indicating fused pins may be misleading.

    3. If none of the above helped, I would allow the unit to warm up for 10 minutes under power, and then see if any of the ICs are running too hot (a thermal camera can be useful but you can wet the end of your finger and see if the ICs are probably defunct if they are running too hot. If you want to go pro, check out the datasheet for the ICs to find out what their operating temperature above ambient should be (vis their thermal resistance and power dissipation) but a wetted finger may identify the issue just as readily. If the ICs are running really hot, check the voltage rails again because it may be an overvoltage issue.

    4.If all that draws a blank, I would connect the unit to a 12v supply and apply freeze spray to the polymer caps under operation. If no useful data was obtained, consider removing them and replacing them with 105C caps of an identical rating in uF and the same or higher max voltage spec.

    I hate to say it, but I would bin the unit and replace it if there were no relatively easy fix because any of a variety of components may have failed due to excessive heat. My approach may not be optimal but it reflects how I would personally approach it.
     
    Last edited: May 7, 2015
  5. Kiwi

    Kiwi

    344
    85
    Jan 28, 2013
    Can you swap the stereo and pocket around to put the stereo at the bottom away from the vents?
     
  6. Skezza

    Skezza

    15
    0
    May 3, 2014
    No schematic. Unsurprisingly, the manufacturer aren't exactly keen on giving any details or support at all. I phoned them again today and they suggested I check the wiring at the back of the unit and suggested that the wiring harness might be faulty, despite the fact I reiterated the fact that heat is a major issue. I did ask about the schematics and was told they don't supply schematics for public use.

    I'm thinking a first hacky fix would be just dump a load of heat sinks on all the IC's. Not exactly the cleanest solution in the world but there we go. While I'm at it, I can look to see if there's any scope for installing a mini fan on the back, although that might not do any good either. I think the unit is probably on borrowed time really. It developed a slight fault last year which I was able to get around but I just think perhaps the components are starting to go. I've had similar head units last much much longer, but this one has had a lot of use and well, shit happens as they say. I imagine the intense heat will have potentially reduced the lifetime of a number of components as well, so I imagine it'll only be a matter of time before they start failing at normal temps. As such, I don't think it's worth investing too much time in it. To be honest, I'm content to buy a new one really. It's been a good unit and I can't really complain too much all things considering, I just might not buy from the same manufacturer as they weren't particularly helpful at all.

    So, I'll install some heatsinks, blow the dust out. I'll check the voltage rails although, it's a car radio, so I don't really understand how overvolting can occur, because I assume the unit is rated to work between 11v and 14v right? The car alternator is fine as well, so it's certainly not to do with that.

    Regarding your suggestion about freeze spray, what would this do exactly? If the caps are overheating wouldn't the rest of the unit fail as well? Or because the engine air is causing the issue is this a variable thing?

    I think I'll disassemble my next unit when it arrives and apply some heat sinks to begin with. This should keep the components from getting too warm and perhaps reduce the effects of ambient temperature.

    Double din I'm afraid. I did see a funny cool stupid solution on the internet for someone else with the same unit in the same car. Below the unit are the coin tray and cup holder, they're push in retractable. He installed a standard CPU fan in the coin tray and drilled some holes in the bottom so it sucks in cold air from the cabin and cools the bottom of the metal chassis. I assume this allows the unit to dissipate more heat? No idea, but he says the issue hasn't occurred since (he posted it about 18 months ago).
     
  7. Skezza

    Skezza

    15
    0
    May 3, 2014
    One thing I did find from the Internet is they're overclocking the CPU. Now I'm not saying the CPU has anything to do with this because it seems the unit functions perfectly fine, as if the DAC has just failed, but the CPU is meant to run at 533MHz and they're running it at 800Mhz. Absolute muppets considering there's no heat sink on it. I imagine that is also adding to the ambient temperature.
     
  8. davenn

    davenn Moderator

    13,765
    1,920
    Sep 5, 2009
    this particular comment in the OP seems to have been overlooked by everyone
    these are all indicators of dry joints ... which may well be a symptom of the heat

    heatsinks on components are not going to solve this issue ... the problematic joints need to be found and resoldered before the OP embarks on any other ideas

    Dave
     
  9. Skezza

    Skezza

    15
    0
    May 3, 2014
    Ok, so what's the easiest way of finding dry joints? I've only ever done it visually and on fairly small PCB's. The motherboard on this thing is pretty complex really, at least compared to my previous experience.

    Driving home tonight, I had the heat on full (intentionally) and it didn't cut out at all. Sporadic eh?
     
  10. Kiwi

    Kiwi

    344
    85
    Jan 28, 2013
    Did you take the photos above showing the internals of your stereo?
    Is today the first time that you have driven the car since they were taken?
     
  11. debe

    debe

    260
    68
    Oct 15, 2011
    With a car stereo with int sound I would be checking the solder on the Audio output IC with a good magnifying glass for small cracks in the solder from viabrations.. At least resolder them.
     
  12. Skezza

    Skezza

    15
    0
    May 3, 2014
    OK, I clearly need to get the unit out and give it the once over.

    Would resoldering them be the way, or trying a reflow? I have done reflows using a heat gun before, thoughts?
     
  13. davenn

    davenn Moderator

    13,765
    1,920
    Sep 5, 2009
    solder them, properly with fresh solder
     
  14. Skezza

    Skezza

    15
    0
    May 3, 2014
    OK, well I think I'll remove the stereo this weekend. I'll get some more photos too. The car is going in for a cambelt and gearbox oil change so it's a good chance for me to get it out and do some work on it. I'm not 100% sure if I'll be able to find the dry solder. To be honest, I'm starting to think that with this unit on its last legs, it might be worth buying a new unit and selling this as working faulty, perhaps I can get something back before it dies altogether??? Dunno. I doubt it's actually worth that much mind.
     
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