DCX2496 issue

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djQUAN

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Joined 2004
quan-diy.com
#1
I had my DCX2496 for almost a year, bought it in the US and brought it over here (got it bnew for almost half the local price over here.)

I have it installed in my car running the mids and highs full active, using two inputs in analog mode, two outputs unhooked, powered by a SMPS I made myself similar to the DSPower! besides that, no other modifications were done.

been running problem free for the whole time I had it until yesterday when I turned on my stereo and there was no sound. all presets I made were gone except the ones that were already there from factory. but it runs normally. so I tuned everything again and it ran trouble free everytime I went in the garage to listen (did it many times) went to take a nap, got back to the garage and then no sound. the presets were wiped out again.

I opened it up and the ROM (is that it? the one for the firmware, plugged in a socket) is tight and still in place. no obvious loose components and a popped electro in the SMPS I made. the popped electrolytic is one of two in parallel in the primary side. besides that I have no idea what could have caused the problem.

I also replaced the two electros which were getting slightly warm (used for the 3.3, 5.0 and 9.0 supplies, I suspect I got bad quality caps there) with better ones.

before and after the fix, all output voltages were correct. I have 1watt zeners on the 3.3, 5 and 9volt lines to protect the DCX incase the regulators fail and go full output so I know there were no voltage surges.

I also know it is not low voltage since the batt voltage is 13.4volts, I have a AC-DC charger and the car is plugged in.

so the big question is, what could be the possible causes of the problem? or any part of the circuit to look at for possible culprits?

any help would be greatly appreciated. 🙂
 
#2
djQUAN said:
I had my DCX2496 for almost a year, bought it in the US and brought it over here (got it bnew for almost half the local price over here.)

I have it installed in my car running the mids and highs full active, using two inputs in analog mode, two outputs unhooked, powered by a SMPS I made myself similar to the DSPower! besides that, no other modifications were done.

been running problem free for the whole time I had it until yesterday when I turned on my stereo and there was no sound. all presets I made were gone except the ones that were already there from factory. but it runs normally. so I tuned everything again and it ran trouble free everytime I went in the garage to listen (did it many times) went to take a nap, got back to the garage and then no sound. the presets were wiped out again.

I opened it up and the ROM (is that it? the one for the firmware, plugged in a socket) is tight and still in place. no obvious loose components and a popped electro in the SMPS I made. the popped electrolytic is one of two in parallel in the primary side. besides that I have no idea what could have caused the problem.

I also replaced the two electros which were getting slightly warm (used for the 3.3, 5.0 and 9.0 supplies, I suspect I got bad quality caps there) with better ones.

before and after the fix, all output voltages were correct. I have 1watt zeners on the 3.3, 5 and 9volt lines to protect the DCX incase the regulators fail and go full output so I know there were no voltage surges.

I also know it is not low voltage since the batt voltage is 13.4volts, I have a AC-DC charger and the car is plugged in.

so the big question is, what could be the possible causes of the problem? or any part of the circuit to look at for possible culprits?

any help would be greatly appreciated. 🙂
Click to expand...

The factory settings are in ROM, the settings you put in are in flash memory. Apparently something wipes out the flash memory. It *may* have something to do with the popped elco's in the supply; there may have been a transient at the output when those blew, and that may have reset the flash mem.

I would run the DCX some longer time on the regular mains and built-in supply. If it doesn't happen then, it is supply related.

jd
 
#3
I won't have any tunes in the car without the DCX so that would be a last resort. would make getting stuck in traffic even worse.

your theory might have something in it. the caps for the secondary caps haven't popped...yet, but they are getting warm with the top cover off so it means there is increased ESR = more ripple. I changed them out for better ones and no temp increase is evident so it should work fine. if the problem appears again I'll try your suggestion of running it on AC for a while.

we also have an ESR meter at work so I could investigate the old caps I took off.

thanks! 🙂
 
#4
I just realized something. the only common situation when the memory loss occurred was when the car was sitting in the garage charging for several hours, then the charger powered down, disconnected then the engine was started. (1st was when I had to go someplace, 2nd time was when I had to move the car in the garage) I have just tried it and memory was not erased so I'm going to try it again tomorrow morning with the same conditions to know if the repair was successful.

edit: I always turn off the radio before removing the key so everything is off during starting.
 
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#5
update: did it this morning (turned off the charger, disconnected it, then cranked the engine) and memory was not wiped out. hopefully, problem won't come back. 😉 how it wiped out the memory...I have no idea.

spikes can't pass through since I have zeners clamping all supply lines except the ones for the analog (+/-15V) so it must have been a combination of turn on/off times of the various rail voltages. will update the thread incase something else occurs.
 
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