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#1 |
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diyAudio Member
Join Date: Mar 2007
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I have the Pioneer DEH-P690UB, with the USB connection, and I'm trying to run a 2.5" hard drive in a USB enclosure from it. I'm having tons of problems. I think it's power or ground related, but I've now rigged it up so that the drive is powered by a separate 5V regulator and not the HU and it's still not working properly.
What happens is that either the drive will fail to spin up (you can hear it trying and trying if you listen), and the HU never is able to read the filesystem, or more annoying, it will be playing fine for anywhere from 10s to 30 mins and then suddenly the hard drive cacks out and the HU either freezes and the USB needs to be reconnected, or it goes back to 'Format Read' and spends 45s reading the format again. First I added a 1000uF 6.3V cap inside the 2.5" drive enclosure, thinking it was just rough power. This seemed to help, but didn't get rid of the problem, as it's so intermittent I'm not sure it did anything at all. Next, I built a simple 7805 regulator and spliced it into a USB cable, getting power directly from the car's 12V supply (bypassing the HU's +5V supply). This 'works', but suffers the same problem as the HU's power, except that it never seems to cause the HU to freeze and need the USB replugged. It's really irritating. Anyone else experienced this? As far as my testing goes, it works fine in my computer. The problem seems worse when the drive is powered directly from the HU rather than from my 7805 regulator circuit, but it seems to be very inconsistent, sometimes it will work fine for an hour, sometimes I'll reset it 5 times and won't be able to get any music at all. I suppose it could be anything; drive is too cold, too moist, bad ground, bad power...any insights? |
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#2 |
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diyAudio Member
Join Date: Dec 2005
Location: Northern California
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sounds like your USB connection does not have a power to run the drive. I have seen this issue on laptops, and its always the same, just power the hard drive from another 5 volt source and bingo problem goes away.
try using a flash drive instead of a hard drive, the HD requires a bunch more power to spin the platter with, and the command electronics involved with the drive. I am sure that your HU has a current limit on the USB port, they all do its part of the spec call out for a SB port...hope this helps ![]() the freezing issues is probably bad ground loops and isolation issues concerning the different power supplies, just use a flash drive your problem will go away for sure. |
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#3 | |
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diyAudio Member
Join Date: Mar 2007
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Quote:
A flash drive might be worth trying to confirm this is a power/hd issue, but it's not a permanent solution. The 80GB HD I want to use is nearly full. If I wanted only a few GB of music in my car, I'd just use MP3 CDs... |
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#4 |
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diyAudio Member
Join Date: Dec 2005
Location: Northern California
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OK at this point I would say its the drive. Hard drives don't like being in cars, Its a bit rough for them. We see Nav system drives fail regularly.
Perhaps you could try a flash , and if that works then another HD. I am imagining that your HU will handle the 80 gig drive or you would not be using one this size. HD's fail, and some fail very regularly till they go completely. Please let me know what you eventually find as this interests me very much so...
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#5 | |
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diyAudio Member
Join Date: Jun 2007
Location: Louis y ana
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Quote:
__________________
Don't worry... you can always turn the gain down! |
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#6 |
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diyAudio Member
Join Date: Mar 2007
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Well, I think I've got this solved. I believe the problems were due to either resistive losses in the USB cable or the deck's USB power supply drooping a lot under the load.
I dragged my meter out to the car, and found that with the drive attached and running, the head unit supplied power was only about 4.7V once it reached the drive. Under heavy seeking/spinup it would drop down as low as 4.5V or a bit lower, and as soon as it reached ~4.5V the drive would fail. With my alternative supply I'd previously measured the regulator output at exactly 5V under 500mA load on the bench, so I'm sure the voltage is not sagging - however at the drive I was measuring 4.6-4.8V most of the time. I measured the USB cable I was using and found that the ground path resistance was about 0.4R. Assuming the V+ path had a similar resistance, the total is almost 1R - at 500mA that's 0.5V of lost voltage, which will kill the drive. I ended up using a barrel jack and beefier wires to connect the power supply, and this brought voltage up around 4.9V even under load. It seems stable now after driving for a couple hours last night. Next time I'll probably just use an adjustable reg and set it for 5.5V. |
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