voltage oddities

[michael]

When we last left our hero, he was haveing voltage problems.
Here's the latest. The radio cuts out (as in the display goes blank) if the idle goes above about 800. So, I'm sitting at a light, stopped, and the radio is playing, I put it in neutral and the idle goes up, the radio goes off. I drop it back into gear, the music comes on. hmmmmmmm.
Last night I left work late enough that I had to drive home with the lights on and BINGO when I turned on the lights, the radio came on. So this morning I started it, the radio display was off while I was at fast idle, I turned on the lights and the radio came on, but was flickering. So, I turned the fan on high and BINGO again the radio came on.
Here's my theory. I have verified with a test meter that my alt. is putting out full field at all times when the truck is running. My radio can't handle a full 15 volts (digital CD player) and it automatically shuts down. But by using up some of the volts with the accesories I can bring the voltage down to a useable level. It's probably my imagination, but the truck even seems to run smoother with all the stuff on.
So, the question: Doesn't this just scream "change your voltage regulator!!!"?
Michael

1967 Commando SW
A labor of love, (mostly labor)

[RRich]

Michael - You've been wanting to replace the regulator for a long time, why not go ahead and do it? I'm sure you won't find it changers anything, but you'll have a spare. Better yet, take the plunge, convert to a GM Delcotron with the internal regulator. Pep Boys has them for about $35 - probably less than the Motorola regulator.
I don't think that's the problem with your radio. The new regulator will do exactly the same thing, limit the voltage to about 15 -- just like it's supposed to do.
I assume you've shaken all the wires looking for a loose connection?

The radio - do you have a ground to it? Or do you figure it's bolted to the dash OK? Does it mount with the plastic shafts? -- oops!
Did you clean the back of the mounting points when you installed it?
Is the dash properly grounded? The bolts may not be enough - turn all the dash stuff on, then measure from batt (-) to a bare spot or bolt on the dash - should be 0 volts! - absolutly nothing! Then measure from batt (-) directly to the radio housing with the radio on - should be 0 too.

Measure the volts getting to the radio - right at the radio wire - make sure it's full voltage.

If all else fails, try replacing the radio - it's an internal problem. Or, if it's really the radio that can't take a full 15 volts, try putting a light bulb in series with the power wire to it, it may drop the voltage just enough to make the problem go away. Use a bulb holder and a brake light bulb and wire it in series with the radio (that's a good way to drop the voltage - the bulb won't light up, but it's resistance will drop it a little.)

Hey - you were in LA and didn't give me a call?

Rich

[michael]

Yes a whole week in Yucipia. Didn't drive the truck down, though. (my parents house). Had alot of personal drama going on.

Anyway. Alright. I'll drop the regulator thing. As far as the radio goes, The CD is stuck and won't eject and won't play either! (it's eating my Cheap Trick!!!!) In fact, now that you mention it, I thought it was odd that the 5 amp power wire went to the constant power source and the 2 amp went to the ingition. That's backwards of how I had it in my Toyota. I thought I was just remembering it wrong. I will do the basic tests you recommend and see what falls out.
I still haven't even looked under the hood at night to see if my plug wires are arcing. Guess I'll just add it to the list.
It just seems so odd that I can get the radio to come on by turning on any of the dash stuff. I hadn't even thought that my fuse box that I put in might be "leaking". But we shall see.
Michael

1967 Commando SW
A labor of love, (mostly labor)

[Paul Calman]

Here's another possibility, though unlikely.
Sometimes a poor connection will conduct properly only when enough amperage passes through, by turning on other devices.
The radio is a small draw, but lights, fan, etc, draw more.
An Ohm meter may not detect it.
I would tap the voltmeter into the radio wire, and see what it reads with and without the extras. A small drop with extras on is normal, an increase would show a bad connection.

To Email, leave my Mom out of it.