Who's good with electronics?

[Mitternacht]

I built this harness to a tee, and when testing the turn signals they light real dimly and then the capacitor on the far right side of the diagram blew. Can anyone help me sort this diagram out?

[phillysrt4]

Did you double check that your electrolytic capacitors are in the correct orientation on the board?

[Mitternacht]

Did you double check that your electrolytic capacitors are in the correct orientation on the board?

Yes, the pos and neg sides were correct.

[phillysrt4]

Are those relays or IC's?

[Mitternacht]

Relays.

[phillysrt4]

so current across 85 and 86 closes the circuit between 30 and 87?

[Mitternacht]

That I don't know. I'm not that experienced with electronic components. I just bought the stuff and soldered it together as the diagram says.

Edit: Would smaller capacitors work?

[phillysrt4]

No problem.

I studied the circuit and it appears sound. If I tracked it correctly then its the kind of sequential where each individual light is on separately and sequentially (as opposed to inner staying on while the middle lights up, then those two staying on as the 3rd lights up).

Two thoughts on this:

1a) Are you using the factory OEM tail lights for this?
1b) If not, do you have LED lights installed? LED lights have a different resistance value than incandescent lights and it appears the circuit takes advantage of the resistance in the bulbs to make it function correctly.

If you have an ohm meter, I would get a resistance value for the OEM set up and compare it to your setup.

Hopefully someone whose DC circuit theory is a little more recent than mine will be able to help.

[phillysrt4]

Also, it looks like you need this circuit for each side of the car (i.e. one for the right, one for the left). Trying to wire the "inner", "middle" and "outer" in parallel from each side will half the resistance value possibly causing an issue.

[Mitternacht]

Oh, wow Thanks for finding that out. I was hoping to build the sequentials where the inner lights stay powered on. Can I rewire this setup to do that or do I have to build another setup from scratch?

Also, yes I'm using OEM lighting.

[phillysrt4]

Sorry, I checked the curcuit again, the inner stays on in a progressive sequential.

Was this circuit from a ford mag?

[phillysrt4]

In any event, from what I can see the schematic is sound. I would double check your wiring.

[Mitternacht]

I actually found the schematic on a w-body forum. It's for my 93 Z34.

[phillysrt4]

Any chance you can take a photo of your assembled circuit so I can double check your wiring?

Also, did you double check the resistance value of the resistors? a 100 ohm resistor should have rings of brown-black-brown and a 150 is Brown-green-brown. If these are wrong that could be a culprit.

EDIT - just saw your edit a few posts ago... no, changing capacitance/resistance values would alter the speed the lights come on and then shut off once the signal from the turn indicator is cut off. Think of the capacitors like rechargable batteries. once the power disconnects they supply a voltage/current for a short period of time. The circuit appears to give you a "wave" of light as power is applied and removed.

[phillysrt4]

Hmm... here's something to look at:

[ame="http://en.wikipedia.org/wiki/Electrolytic_capacitor"]Electrolytic capacitor - Wikipedia, the free encyclopedia@@AMEPARAM@@/wiki/File:PaperElectrolyticCapacitors.jpg" class="image"><img alt="" src="http://upload.wikimedia.org/wikipedia/commons/thumb/8/86/PaperElectrolyticCapacitors.jpg/220px-PaperElectrolyticCapacitors.jpg"@@AMEPARAM@@common s/thumb/8/86/PaperElectrolyticCapacitors.jpg/220px-PaperElectrolyticCapacitors.jpg[/ame]

Under the section on reverse bias:

Modern capacitors have a safety valve, typically either a scored section of the can, or a specially designed end seal to vent the hot gas/liquid, but ruptures can still be dramatic. An electrolytic can withstand a reverse bias for a short period, but will conduct significant current and not act as a very good capacitor. Most will survive with no reverse DC bias or with only AC voltage, but circuits should be designed so that there is not a constant reverse bias for any significant amount of time.

The bolded parts refer to what happens when a circuit is designed incorrectly, or when an electrolytic capacitor is installed backward, or when a circuit is impropertly built such that the circuit acts like the capacitor was installed backwards.

I would double-double check that the positive side and negative sides of those electrolytic caps are oriented correctly.

EDIT - i gotta head out... i'll check the thread when I get back later today to help if someone else hasn't solved the issue

[phillysrt4]

I got your photo and sent a PM with my thoughts on whats wrong. If it doesn't resolve I'll post publicly what I've found so that hopefully someone else can help.

[phillysrt4]

bump for update?

[Mitternacht]

I just wired the car back up for now. This is something I'm gonna have to take my time with. Thanks for your help, I appreciate it.

[phillysrt4]

So taking those two out of parallel didn't solve the problem? :(

[Mitternacht]

the first relay just clicks and nothing happens.