Audio Systems: intermittant stereo power and dead battery, power spikes, nissan maxima

Question
Hello, I have a stock Bose radio system in a 1996 Nissan Maxima that is frustrating me, and I hope to avoid replacing the radio. Please help.

1) noticed my stereo, cd amp and power antenna began to turn on and off with increasing frequency (a few seconds on then a few seconds off) until finally it stays off, and I can't turn it back on. Sometimes it plays for a while, before this happens. I see the display lights going off and on, and here the sound of the amp relay and power antenna doing it to. at first I thought this was heat related, but sometimes it happens when I first start the car and often won't work at all. Sometimes it works for a week or two, but always it reoccurs.

2) often it begins when I hit the turn signal or turn on the head lights, but then carries on as above regardless of any small (what i presume are) power spikes.

3)It seems that when the unit is going off and on every ten seconds or so, and it is in the "off phase" I can hit the power button and the unit stays off (doesn't continue going of and on)...maybe the problem is just after the power switch inside the unit.

4) Although there may be an undiagnosed second problem, if I leave the car for a week or two, I often find a dead battery. It is a new battery with a good alternator and I've checked the volts, charging and non-charging and they are within spec. The ignition-off power drain seems just slightly higher than spec, but not much.

5)I have since replaced a "burned out antenna motor" per dealer and "accessory relay" when the dealer duplicated my problem. All fuses and fusable links seem intact. Finally they said to replace the radio.

6) I have pulled the radio out twice and checked connections. The only time it made a difference was once when I removed and re-inserted the antenna plug in the back of the unit. It seems it may ground through the antenna, this was before the antenna motor was replaced.

I am lost. I think it is an internal switch diode or something. I will pull the whole unit out and see if the battery drains when the unit is out. Maybe someone can bench test the unit and try to reproduce the problems. I can't afford to replace the radio if doing so does not correct the problem.

Thank You very much in advance for your time.

Skip Weller


Answer
Skip,
On many of these Bose stereos I find defective solder connections on the main power switching/control transistors. In some stereos I found the cause to the cars battery draining was due to a shorted transistor which kept the stereo on all the time, even with the display off. You might want to go over the complete circuit board/s with an X10 magnifier and look for defective solder connections, pay close attention around the power connector input area.


TOM,
T&D ELECTRONICS
tdeser@zoominternet.net