Lights flickering

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Bwana

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When I turn my headlights on, I get a flickering in both the interior lights and the head lights. Not really bad, just enough to notice. Doesn't change with RPM, same cycling, looks to be about 50-60 hZ from idle to 3500 RPM. Charging system seems to be OK as I never have a flat battery but I haven't checked the charging voltage yet.

Any suggestions?
 
Yeah, voltage regulator or ground quality. The alternator could be on its way out, since flickering indicates unsteady current/voltage output.
 
Bwana said:
When I turn my headlights on, I get a flickering in both the interior lights and the head lights. Not really bad, just enough to notice. Doesn't change with RPM, same cycling, looks to be about 50-60 hZ from idle to 3500 RPM.
Click to expand...

Wow, that is a seriously weird symptom. Around 60 hz you say? If it varied with rpm, then sure, the alternator would be the likely culprit. I can't see how a bad ground would cause a 60 hz flicker. Maybe a bad mechanical VR would - if you put your hand on the VR, can you feel it buzzing?
 
Do you have points? I had flickering lights. Turned out to be badly pitted points.

Bwana said:
When I turn my headlights on, I get a flickering in both the interior lights and the head lights. Not really bad, just enough to notice. Doesn't change with RPM, same cycling, looks to be about 50-60 hZ from idle to 3500 RPM. Charging system seems to be OK as I never have a flat battery but I haven't checked the charging voltage yet.

Any suggestions?
Click to expand...
 
decampos said:
Do you have points? I had flickering lights. Turned out to be badly pitted points.
Click to expand...

I don't have a better theory than the ignition points. But, I would expect the rate of flicker to vary with rpm if Bwana's problem was being caused by his points - he says the frequency is constant.
 
60Hz? Another Power Line interference phenomenon...

Can you hear any hum on the radio?
 
Been out of pocket, sorry!

No points, running Petronics I've got a D-Jet but don't think that's it. I think I've only noticed it since daylight savings time when I started friving to work in the dark. Could haave been going on for some time without me noticing it. The 60hz is strictly a guess, could be anything. I'm just familiar with what that frequency looks like from work.

Definitely does NOT change with RPM. First thing I checked

I'll check the VR when I get the chance. It's at the shop right now for some window work, I just wondered if it was worth it to have the guy check it out. I don't want to spend $$$$ on something chronic and not an issue, just an annoyance.
 
Bwana said:
I've got a D-Jet.
Click to expand...

I know zip about D-Jet. How much electronics does it involve? Is D-Jet the old school, analog system, or a more modern, computer-controlled system? If the latter, then a clean power supply is critical. I suppose the fact that your car is running OK suggests that D-Jet doesn't have a lot of sensitive circuitry!
 
About as old school as you can get. It's the original electronic FI system but it's analog, not digital. The control box looks like something you would buy from "Heathkit" (iIf you remember that!), full of resistors, diodes, and capacitors all on a circuit board. It will probably run on anything, apparently pretty reliable.
 
Bwana said:
Been out of pocket, sorry!

... The 60hz is strictly a guess, could be anything. I'm just familiar with what that frequency looks like from work.

Definitely does NOT change with RPM. ....
Click to expand...

The 60Hz flicker on incandescent home bulbs is really 120Hz because it is AC, while your flicker cannot be AC. I do not see the incandescent bulb flicker due to thermal inertia of the filament. If you see it in your filament headlights it could be because it is 60Hz vs 120Hz, or the waveform much narrower in duty cycle.

This is a neat puzzle, let's give it a couple of days and do a poll...
 
The final answer here was to replace the alternator. Turns out the flickering was because of a partially bad diode in the voltage regulator. It wasn't bad enough to cause a complete failure of the charging system but was bad enough to cause the flickering. The tip off was indeed that the flickering did not change with RPM.

New alternator with the upgraded internal voltage regulator
 
Bwana said:
The final answer here was to replace the alternator. Turns out the flickering was because of a partially bad diode in the voltage regulator. It wasn't bad enough to cause a complete failure of the charging system but was bad enough to cause the flickering. The tip off was indeed that the flickering did not change with RPM.

New alternator with the upgraded internal voltage regulator
Click to expand...

I've had the same issue for a while. What alternator are you using that has an internal regulator? Mine is external.

-Scott
 
Bwana said:
The final answer here was to replace the alternator. Turns out the flickering was because of a partially bad diode in the voltage regulator. It wasn't bad enough to cause a complete failure of the charging system but was bad enough to cause the flickering. The tip off was indeed that the flickering did not change with RPM.

New alternator with the upgraded internal voltage regulator
Click to expand...


Interesting that it was RPM independent.
The alternator AC frequency is definitely a function of the RPM. If the rectifier diode(s) fail one may see a flicker that is a function of the RPM. Don't know about the regulator diode role and how the frequency would be constant.
 
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