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Solid state weirdness
https://slantsix.org/forum/viewtopic.php?t=23422		 Page 1 of 1
Author:  Jopapa [ Thu May 31, 2007 6:43 pm ]
Post subject:  Solid state weirdness
Last night I put a solid state regulator on my instrument panel, and when I went to test it this morning, the gauges worked (very slowly though) when the engine was off or idling, but when I gave it gas, they'd cut out. This happened to anyone else before? I remember doing the conversion on my ex's Dart, but don't think I used a capacitor when I did that one, and it didn't have any issues. Could the cap be what's causing this weirdness here? Any ideas?
Author:  Pierre [ Thu May 31, 2007 8:09 pm ]
Post subject: 
Doubt it, if anything the cap would help. Is this a consistent thing? Do the lights and switches still work when you step on the gas? What if you keep your foot on the gas and keep the rpms held high?
Author:  Jopapa [ Thu May 31, 2007 8:18 pm ]
Post subject: 
Quote:
Doubt it, if anything the cap would help. Is this a consistent thing? Do the lights and switches still work when you step on the gas? What if you keep your foot on the gas and keep the rpms held high?
Yeah I drove it around just to see if it'd clear up, but it didn't change. I had the headlights on the whole time, but still, I can't be driving around at night with no working gauges :?
It was happening even when holding the engine at high RPM. Everything else works fine though.
Author:  Pierre [ Thu May 31, 2007 8:39 pm ]
Post subject: 
That almost sounds like something mechanically linked to the gas pedal... wire get wrapped around it? Something flexing upon acceleration.

Swap the mechanical one back in and see.
Author:  Slanted Opinion [ Fri Jun 01, 2007 9:28 am ]
Post subject: 
Did you heat sink the regulator?
Author:  KBB_of_TMC [ Fri Jun 01, 2007 10:09 am ]
Post subject:  solid state
A mechanical regulator puts out +12V until it warms up; the solid state puts out +5V instantly, so the gauges will warm up slower initially- that's totally normal. I've thought about building a circuit to emulate the old regulator, it wouldn't be that hard.

I would look for a loose ground at the engine and/or a broken engine mount - if the input voltage goes too high, most electronic regulators' internal thermal limiting shut themselves down...
Author:  Jopapa [ Fri Jun 01, 2007 6:29 pm ]
Post subject:  Re: solid state
Quote:
A mechanical regulator puts out +12V until it warms up; the solid state puts out +5V instantly, so the gauges will warm up slower initially- that's totally normal. I've thought about building a circuit to emulate the old regulator, it wouldn't be that hard.

I would look for a loose ground at the engine and/or a broken engine mount - if the input voltage goes too high, most electronic regulators' internal thermal limiting shut themselves down...
Yeah I had to remember that when I first turned it on, so the slow gauges didn't worry me at all. If you do up one of those circuits, be sure to post up instructions on it. I'd love to have a well working gauge cluster to last me until I can install all aftermarket gauges.

Edit, I double checked all my grounds and everything's okay. I'm going to do alot of work on strengthening my body and engine grounds sometime in the near future (got all the stuff, just gotta take the time to do it). I don't think it's getting too hot, since it's got the better heatsink (with Artic Silver thermal compound) on it. I'll hold a finger on it next time I test the system to see how hot it's getting.
Author:  Slanted Opinion [ Sat Jun 02, 2007 10:30 am ]
Post subject: 
How about replacing the 7805? They are a dime a dozen, maybe you have a flakey one.
Author:  Jopapa [ Sun Jun 03, 2007 11:03 am ]
Post subject: 
Quote:
How about replacing the 7805? They are a dime a dozen, maybe you have a flakey one.
I'm thinking you're right. I switched the poles on the capacitor, same problem. Removed the capacitor, same problem. Desoldered everything and put the mechanical regulator back in, gauges work perfectly. I ordered two regulators, but decided to just leave the mechanical one in until it dies or I have all my new gauges, whichever comes first.

It's possible I cooked the regulator myself too. I used silver-bearing solder and had my soldering iron (digital Radioshack one, pretty nice) set to 600 degrees. I kept contact time to a minimum, but still...
Author:  emsvitil [ Sun Jun 03, 2007 1:03 pm ]
Post subject: 
Can you measure the amp draw of the instruments?

I'm thinking you're drawing too much current for the 7805, and when you raise the speed above idle (and the supply voltage rises), the 7805 goes into thermal shutdown.
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