Rbm
Professional amateur
I would suggest you you rethink that..impedance is not resistance. Good luck.
1963 Dodge Dart for the Wife....
- Thread starter JimKueneman
- Start date
JimKueneman
Mopar Nut
A resistor is impedance, real part of the impedance L's and C's create the complex part of the impedance. The resister trick has been done by old radio repair shops for years when the transition to 4 ohm was happening. Also I design high reliability power circuits for a living, so I’ll need a circuit design explanation as to how the resistor can hurt the output power transistor. That is how you limit current in any transistor circuit to keep the device in its SOA area. Lowers the current and splits the power dissipated between the transistor and the resistor. Over current and thermal are main killers of transistors (over voltage but that would kill the transistor regardless).
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Rbm
Professional amateur
Audio signals do not behave as power curcuits (?) Speaker impedance is listed as nominal..can vari with frequency as little as + - 10 ohm with low frequencies as high as 60 . For reference, ive been in the audio business for 30 + years.
sprint_9
Rookie
This is always one of those fun topics I see discussed from time to time. Personally the way I understand it, and for load balancing like Jim is doing adding a resistor will work. You're right impedance varies per driver depending on frequency, but adding a 4 ohm resistor raises the entire sweep and gets him above where he needs to be. The net load the stereo sees is now at or above where it was designed to run.
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JimKueneman
Mopar Nut
I am not looking for awesome sound out of a 60 year old radio! If I can hear something it is a success.... The wife only cares about the Bluetooth anyway....
JimKueneman
Mopar Nut
JimKueneman
Mopar Nut
It think so too. Summit could not get me small bolt pattern Crager SS's in 15" (boxes marked 15" but not what was inside). I think these are perfect. The Cragers have too many sharp angles for this body style, these are smooth and art deco like. The car body lines are the same.... I am glad Summit had problems.
JimKueneman
Mopar Nut
5 hour round trip drive to meet a super nice fellow early A-Body guy with a collection of old Mopars. He parted with his last '63/'64 cluster so I could get a gas gauge. I will likely try to rewind my old one and then restore this dash like I did mine for someone to have a turn key restored cluster for their old Dart.
Installed the Real Time Engineering electronic regulator as the one in the new gas gauge clear got hot as the bimetallic strip was not straight and the wires where black. Bend the points out so it could not touch and snipped the ground on the NiChrome wire for the regulator heater so it could not short things out. Used the supplied resistor to test things out, the 10 ohm should peg the the needles.. Crap I just remembered I did not paint the needle orange!!!! It is stinking hot.... it was going to be over 115F where I was south of Phoenix and it is 95 here but the storms are building.
Installed the Real Time Engineering electronic regulator as the one in the new gas gauge clear got hot as the bimetallic strip was not straight and the wires where black. Bend the points out so it could not touch and snipped the ground on the NiChrome wire for the regulator heater so it could not short things out. Used the supplied resistor to test things out, the 10 ohm should peg the the needles.. Crap I just remembered I did not paint the needle orange!!!! It is stinking hot.... it was going to be over 115F where I was south of Phoenix and it is 95 here but the storms are building.
JimKueneman
Mopar Nut
Dash is flipped back down, radio is out (did not work well) and the order is into the electronics store in Tucson for pickup later this morning... fingers crossed this all that is wrong. Basic checks of the output stage indicate it is not blown so that is good.... Interesting old capacitors that have multiple caps in a single package... I needed to create a "ring of ground" for the old Bendix cap.... Ready for the new ones.
JimKueneman
Mopar Nut
New electrolytic caps, a new bulb and the world is good. Total cost $5.00.... of course for an electrical engineer to go to an electronics surplus place the trip cost more like $100......
New capacitors are SO MUCH smaller than they were 60 years ago!
Here is a video of the final product...
https://drive.google.com/file/d/1Rgu5FMsTkUUG8jYfhJaXTBteic2nTcTd/view?usp=sharing
New capacitors are SO MUCH smaller than they were 60 years ago!
Here is a video of the final product...
https://drive.google.com/file/d/1Rgu5FMsTkUUG8jYfhJaXTBteic2nTcTd/view?usp=sharing
JimKueneman
Mopar Nut
More under dash details. DMT wiper pivot kit and the wipers are installed and functional. Bead blasted the heater door cable clips and the heater controls are done. Installed some insulation then removed the cracked and disintegrated covering on the shift cable. After that bead blasted the shift and speedo cables.
JimKueneman
Mopar Nut
After blasting it was time to seal the shift cables. They do not have seals and transmission fluid is allowed to travel up them so they need to be sealed. I like this Permatex sealer that my machine shop buddy uses so I smeared a coating on the cable then slid on 3/8" shrink tubing. After shrinking it I then put on 3 more layers. Basically used up four of the 4' lengths.
JimKueneman
Mopar Nut
Once done fixed the bent cable holders so the cables came straight into the shifter mechanism and replaced the seal in the speedo gear. Lubed the cable and installed. Once I get a couple questions answered the dash will be rolled up and bolted in for good.
JimKueneman
Mopar Nut
Dash is in for good (I hope).... vapor barriers in (Lowes 6 mil plastic, one roll has done 4 cars), letting the carpet layout for a week and mocked in the windshield chrome!
JimKueneman
Mopar Nut
Upholstery place called and the rear bottom frame had rot.... apparently a common disease for A-verts. Spent a few hours here and there this week restoring it. Dropped it off at 4:30 this evening. Upholstery will be done early next week. Gotta get the seat parts restored and painted this weekend... piece of round rod and a 22 gauge panel from Ace then a few scraps off the body panels and some blasting and epoxy primer. Just like new.
JimKueneman
Mopar Nut
JimKueneman
Mopar Nut
Thanks