Pioneer Appradio range critical design flaw exposed.
Okay so an odd one for you today, as we tend to do a lot of game development on the go, one of the more off the wall things we do is use the Pioneer head units HDMI inputs on our vehicles to experiment with scaling and readability for game UI and text elements on lower resolution displays (generally sub-720p), it also works as a handy 16:9 secondary display for running live game code from a laptop.
About 13 months ago both the SPH-DA09 “Appradio” units in our vehicles failed within a few weeks of each other, not electrically, but in what can only be described as progressive deterioration of touch screen functionality.
Both units were replaced with new units of the same model for the sake of being able to easilly switch the units over and knowing where we stood with compatibility and configuration for our uses.
This past two months the same telltale marks in the touch panel began to appear on both new units, at this current time one unit is now entirely non-functional, and the other sporadically works depending on where on the screen you try to register a touch, so this has prompted me to have a dig around and figure out why before going out and replacing these units a second time.
Researching the frequency of the issue
First port of call is to check out second hand markets, if we look in the units native country, the most obvious choice is Yahoo Auctions, which yields the following:
All three units available for purchase are described as junk, and if we individually check each of these three auctions, we can understand exactly why.
The first of which lists the fault as follows:
This basically says that touch input is completely non functional, and if we check out the image we see the problem visually too.
The next auction shows us this in even greater detail, with the display turned off:
The last auction also shows us the same effect from another angle, showing the individual touch grid lanes running vertically across the screen
Now, if we move away from the SPH-DA09 to other models in the range, such as the SPH-DA05, we see that the problem isn’t limited to one particular model.
Indeed, a google search for “Pioneer delamination” yields exactly the same issue happening on international models of the Appradio 2, 3 and much newer models such as the SPH-DA120 (Appradio 4), the latter raising an eyebrow the most as it’s a completely different design to the Appradio 2 and 3.
What we’re essentially dealing with is a capacitive touchscreen, so we can infer from this that during manufacturing, Pioneer or their third party supplier bond a capacitive touch panel to the front glass, much in the same way that modern capacitive smartphones have a touch panel bonded to the main glass.
As shown in this simplified diagram, in order for the touch panel to register a touch input, the di-electric adhesive passes through the small charge in a finger press to the touch panel, this prevents other objects from accidentally pressing on the screen as it requires an organic, or at least, a material carrying a similar charge to register the input.
In this particularly bad unit, we can see that the individual cells of the touch panel are showing, with both the vertical and horizontal seperators clearly visible too, each of these small cells such as the one highlighted in green register a touch input for that particular cell.
So the end result is that the di-electric adhesive bond between the touch panel and front lens is failing, breaking the circuit, if you will, between you finger input and the touch panel, thus failing to register touch input.
It’s clear from both the asian and US market for these devices that the common link is heat, both the direct heat from sunlight and from ambient temperatures in cars increasing, something that should obviously be factored in when designing products to be used in vehicles.
But, it isn’t just the direct and ambient heat in the vehicle causing this, it’s also the heat generated from the unit itself.
In this teardown we see that the back plate for the tilting display unit is metal, along with the backing frame for the whole tilt function, this acts as a large conductor, either slowly cooling or slowly warming the unit, this when in a vehicle with the AC turned on, the face temperature of the screen drops rapidly while the back plating remains hot, causing a temperature delta between the front glass and touch panel.
In instances where the car has been stood in colder conditions, heating the vehicle via AC rapidly causes the same effect with opposite temperatures, the front display will warm while the metal plate retains it’s colder temperature and holds the touch panel temperature low, again causing a temperature delta.
A third factor is the inadequate cooling of the units hardware itself, with only a small fan located at the back of the unit supplying cool air to part of the mainboard and not effecting the display in any way.
Over time these deltas will eventually cause the bond to fail in the display, resulting in at first, a cosmetic issue, but as the bond continues to fail, partial then complete failure of touch registration.
Given that this is an often reported issue to Pioneer through the series of Appradio devices from 2 all the way to the most recent 4, it’s highly unlikely that Pioneer were not aware of the issue prior to the release of the Appradio 4 and potentially 3, so their inaction on modifing the design to prevent this is worrying.
With the release of the Appradio 5 on the horizon, it will be interesting to see if Pioneer have made any modifications to the production process and cooling design, as if they have not and new units start to suffer from this now well documented issue, then it would fall into intentional negligence territory.
I have reached out to Pioneer Japan regarding this issue and will update if I hear anything back, but for the time being if you own a Pioneer Appradio and you’re starting to see screen issues as shown in the above examples, get ready to start losing touch input.