Voltage Limiter

-
Rustyfish

Rustyfish

Member
Joined
Sep 15, 2015
Messages
1,334
Reaction score
1,059
Location
Shawnee, KS
So I have been trying to do many of the electrical upgrades recommended on FABO. As of now I have no instrument lights that work so today I decided to pull my gauge cluster and see what's what.

Background: 1966 Barracuda 318 column shift. Almost all wiring was original when I got it and aside from the giant hole cut into the dash for an aftermarket stereo at some point, it all seems to be pretty much unmolested (except a cheesy taiwanese security thingy ma bob under the dash that I just pulled out).

I get the cluster out and it appears there is not limiter attached to the back.

Question 1-Should I assume the limiter is inside the speedo?

Question 2-One of the light sockets is missing, would this prevent the rest of the lights from working?

Question 3-If I have an internal limiter, is it possible to add and electronic unit on the back of the gauge? I have seen this mod I think, but there were studs that I don't seem to have.

Thanks for the help as usual.
Rusty Fish (Bruce)
IMG_0486.JPG
IMG_0485.JPG
 
The limiter is next to the connector not inside the speedo. If one socket is missing it will
not affect the other lights as they are wired in parallel (12V) from the headlight dimmer
The odd looking prong next to the connector plug is a mechanical type voltage regulator, takes 12V and reduces it to 5V for the instruments. I would rewire to eliminate this if it even
stills works and replace with a solid state 5v regulator (google 7805) sold online or Radio
Shack about 2 bucks. Use one 7805 for each of the 4 gauges as they are rated a 1amp.
Also rewire and resoder all the PC board connection joints. I suggest you bench test the
dash before reinstall. basically you will have 5V on the one side of each gauge, the other
side of the gauge(s) will go the sending unit(s). You can use a resistor or variable resistor of
the appropriate valve to simulate the sending unit. Use your battery hooked up as the 12V
source.
 
On a 66 B-Cuda, the voltage limiter is part of the gas gauge, and in the gas gauge it self, that's why you don't see it on the back of the cluster.. I Have been trying to get my gauges (on my 66B-Cuda) to work properly, and I have the FSM. It is quite confusing as to what terminals, are used to check gas gauge, on the back of the cluster. Looking at the back, you have to use some of those terminals on the right, side to check it out. I have figured out the 12V in terminal, but I can't figure the 5V out terminal, FSM is confusing. some are on the printed circuit, and are wired thru the pins to the other side. If you find out let me know. I'm at the point, I am going to put after market gauges in the factory places.
barracudadave67
 
66jim said:
The limiter is next to the connector not inside the speedo. If one socket is missing it will
not affect the other lights as they are wired in parallel (12V) from the headlight dimmer
The odd looking prong next to the connector plug is a mechanical type voltage regulator, takes 12V and reduces it to 5V for the instruments. I would rewire to eliminate this if it even
stills works and replace with a solid state 5v regulator (google 7805) sold online or Radio
Shack about 2 bucks. Use one 7805 for each of the 4 gauges as they are rated a 1amp.
Also rewire and resoder all the PC board connection joints. I suggest you bench test the
dash before reinstall. basically you will have 5V on the one side of each gauge, the other
side of the gauge(s) will go the sending unit(s). You can use a resistor or variable resistor of
the appropriate valve to simulate the sending unit. Use your battery hooked up as the 12V
source.
Click to expand...
What you see in the pics is what I have, there is no limiter on the back of the cluster. Are you referring to the metal clip covering what looks like a small threaded bolt?
 
replaced my entire gauge set with AutoMeter ProComp II - the small ones fit with no cutting, the speedo and tach just needed some Dremel work on the back. The aluminum backer was removed.

IMG_20160318_105041.jpg
barracudadave67 said:
On a 66 B-Cuda, the voltage limiter is part of the gas gauge, and in the gas gauge it self, that's why you don't see it on the back of the cluster.. I Have been trying to get my gauges (on my 66B-Cuda) to work properly, and I have the FSM. It is quite confusing as to what terminals, are used to check gas gauge, on the back of the cluster. Looking at the back, you have to use some of those terminals on the right, side to check it out. I have figured out the 12V in terminal, but I can't figure the 5V out terminal, FSM is confusing. some are on the printed circuit, and are wired thru the pins to the other side. If you find out let me know. I'm at the point, I am going to put after market gauges in the factory places.
barracudadave67
Click to expand...
 
I am going to do what Gone fishing has done. I'm tired of playing with the stock ones. The stocks were nice looking, but a bad electrical design.
Another member here has done that also to his 66. He road races with his. thats where I got the idea. Fishracer66 is the member. he has some pics on his site, on this forum.
Gonefishen, Nice dash, got anymore pics,??.

barracudadave67
 
here's the other side

matched the layout to my Journey so it would be easier to quickly identify speedo vs tach

barracudadave67 said:
I am going to do what Gone fishing has done. I'm tired of playing with the stock ones. The stocks were nice looking, but a bad electrical design.
Another member here has done that also to his 66. He road races with his. thats where I got the idea. Fishracer66 is the member. he has some pics on his site, on this forum.
Gonefishen, Nice dash, got anymore pics,??.

barracudadave67
Click to expand...

IMG_20160318_105048.jpg
 
There's so much wrong info in this thread ( separate regulator for each of 4? gauges for example ) that I wont attempt to correct it all. I will point out the logo on those aftermarket gauges resembling chevy bowties. Good luck to all.
 
RedFish said:
There's so much wrong info in this thread ( separate regulator for each of 4? gauges for example ) that I wont attempt to correct it all. I will point out the logo on those aftermarket gauges resembling chevy bowties. Good luck to all.
Click to expand...

Back to the original problem then, what is the "best" fix for the internal VL?
 
rustyfish said:
Back to the original problem then, what is the "best" fix for the internal VL?
Click to expand...
An external limiter or regulator. If you'll remove the 3 nuts holding that fuel gauge in, take it out and look at its backside, you'll find a sliver of metal on the back of it that conducts its chassis ground ( there's a unpainted spot in the housing here also ). A layer or 2 of electric tape over that will interrupt the original internal limiters ground path so its no longer a factor. This gauge now closely resembles any 2 post gauge in mount and function. And while your looking at the back of this gauge... the fiber backboard has 3 letter markings. 'I' is in, that's 12 volts. 'A' is altered/adjusted voltage, that 5 volts. 'S' is sender/signal. ( paint pens,,,, some color coded dots on the end of these studs would be mighty dang handy right now and later )
Reinstall the gauge minus the piece of metal clipped over the 1 stud ( its no longer required, nor is the noise suppression capasitor.
Buy whatever limiter or regulator that you can mount somewhere ( a few different units out there with various features and prices ) and attach its 3 wires. 12 volts in, 5 volts out, go one their respective studs on that fuel gauge with ring terminals, internal toothed washers and additional hex nuts ( #10-32 ). Then the chassis ground to somewhere, and done.
The printed circuit boards ( and harness wiring in your case ) will conduct the 5 volts to the other 2 gauges.
 
Last edited:
And by the way... I do believe I see a contact pin missing from your printed circuit board. That pin conducts to 3 of your illumination sockets. So looks like that's why they don't work. That's fixable also. Just solder a length of wire to that copper trace anywhere available and add male female spade terminals to the respective wire ( should be orange ). I'll assume for now that illumination is good at the smaller circuit board ( orange wire makes up there ). Maybe just new bulb(s) required over there.
 
RedFish said:
And by the way... I do believe I see a contact pin missing from your printed circuit board. That pin conducts to 3 of your illumination sockets. So looks like that's why they don't work. That's fixable also. Just solder a length of wire to that copper trace anywhere available and add male female spade terminals to the respective wire ( should be orange ). I'll assume for now that illumination is good at the smaller circuit board ( orange wire makes up there ). Maybe just new bulb(s) required over there.
Click to expand...

I bet that pin is still in the socket in the car.

RTE makes 2 different limiters, IVR 3 and IVR 4, but not sure which one I would need.

And still not sure quite how to remove the fuel gauge. It seems to be held in back by that metal tab surrounding a bolt from the middle of the gauge itself.
IMG_0487.JPG
 
Yeah they poked a metal clip over that stud. Best I can guess is because it would heat up. Pinch it and pull it out before or after the gauge is removed. Replace that clip with a nut typical to others.
Loose or broken contact pins is common. They were only crimped in place. There are ways to repair a broken out pin but all that really aint necessary. Some models don't have printed circuit boards. Instead every wire is attached direct to whatever. What I suggested is the same. You have ample space to scratch away some of their blue ink and solder a wire to that copper trace. But... If you want to try and reattach the pin, others might post how they went about it. Just know this... There is very limited space for solder, screw heads, anything additional underneath the board.
 
Last edited:
rustyfish said:
Nevermind, it just popped out. I don't see the letters you mentioned though on either side of the circuit board.
Click to expand...
I said the "fiber backboard", on the instrument itself. Those threaded posts are swedged into it. Its surely brittle and fragile as hell so be gentle in handling.
One can crack/break that board in overtightening the nuts too.
 
RedFish said:
I said the "fiber backboard", on the instrument itself. Those threaded posts are swedged into it. Its surely brittle and fragile as hell so be gentle in handling.
One can crack/break that board in overtightening the nuts too.
Click to expand...

Yep got it all apart now. Is the metal piece that is to be covered up the strip in between the 3 studs on the back of the gauge?

Voltage limiter recommendation? Like I said, RTE has 2 different ones.

Appreciate your help
 
RedFish said:
There's so much wrong info in this thread ( separate regulator for each of 4? gauges for example ) that I wont attempt to correct it all. I will point out the logo on those aftermarket gauges resembling chevy bowties. Good luck to all.
Click to expand...

Said use a separate 7805 for each gauge, gas,oil and water sorry only 3.
 
rustyfish said:
Yep got it all apart now. Is the metal piece that is to be covered up the strip in between the 3 studs on the back of the gauge?

Voltage limiter recommendation? Like I said, RTE has 2 different ones.

Appreciate your help
Click to expand...

I believe either could work. One was designed for models that plug directly into the board(4) and the other (3) would mount on the board and wired to the terminals. The 66 barracuda used neither but they both can be "wired" in the same way as the 7805/ heat sink/ resister modification that can be found in a few posts. If ya are not feeling like soldering up the small cheap parts You can use the RTE products.

THis is an ok version of the mod done on a 65 .. http://earlycuda.org/techdocs/DashGaugeVR.pdf
 
snate66 said:
I believe either could work. One was designed for models that plug directly into the board(4) and the other (3) would mount on the board and wired to the terminals. The 66 barracuda used neither but they both can be "wired" in the same way as the 7805/ heat sink/ resister modification that can be found in a few posts. If ya are not feeling like soldering up the small cheap parts You can use the RTE products.

THis is an ok version of the mod done on a 65 .. http://earlycuda.org/techdocs/DashGaugeVR.pdf
Click to expand...
That person in the link did open the gauge, saw and showed what is somewhat typical of these fuel gauges. Heat and nastiness in the air, takes its toll on these instruments. Some more than others.
When they were new the goldish fiberglass fiber wound insulation on the resistor wire was hardly visible. Plus the bi-metal beam was arrow straight at room temperature.
A temp' gauge rarely goes beyond about half way and doesn't have the added limiters heat in it either so most of those of the same age will look a lot better/newer.
The gas gauge goes to 10 ohms/full often, producing more heat and more crud buildup which eventually restricts movement. So bottom line... A replacement solid state regulator is not a cure all.
 
You must log in or register to reply here.
-

Back
Top