67 gauge voltage regulator keeps blowing

[6T7Merc]

So the original regulator on my cluster blew so i replaced it with another regulator from LMC. This one seems to have gone too after almost no use. Is there any way I can bypass this or do the gauges absolutely need the 5 volts? I dont want to have to replace this thing again to have the same thing happen for whatever reason. There arent any shorts that I can find and everything checks out when I test the posts on the reg with a voltage tester.
Any ideas would be great. Thanks.

[flyboy71]

Yes 5 volts is required in order for the gauges to indicate correctly and to prevent them from being damaged. The regulator is really a bi-metallic strip with a heater wound around it that switches on and off to send a pulsating voltage to the gauge so it doesnt really regulate a steady voltage in the true sense. When first installed do the gauges work at all? Go full scale? Is the case of the regulator at ground potential? One terminal should be close to battery voltage potential and the other should be pulsing if you connect a meter to it. The shop manual suggests pulling the wire off a sending unit and connecting a test light from the wire to ground and checking for a blinking on and off if the circuit is functioning properly.

[fordman]

here is a nos one on ebay. this guy is a good seller. http://cgi.ebay.com/ebaymotors/MID-60S- ... ccessories

[m-mman]

Wow I have only replaced maybe two in my life.
A really simple design. As described above it is really just a "turn signal flasher" for the gauges.

Steady 12 volts fed to one side, comming from the key.
The other side will NOT flash unless there is a load on it. Like a turn signal missing a bulb(s)
If it flashes faster than a slow turn signal, there is too much of a load.

To work properly it does need to have its case grounded . . . .
I guess that if it were not well grounded perhaps it could draw too much power to make the 'flash' and that might overheat the bimetallic spring . . .

[flyboy71]

Heres the diagram showing the innards of the IVR. I also included the procedure to check if its working properly.

[6T7Merc]

Alright thanks guys. Ill do some more bench testing tomorrow and see if I get anywhere.

[fordman]

thats cool that should help lots of people.

[6T7Merc]

So I am about to pull my hair out.
I just got another regulator from LMC and installed it. Then today went and turned the key on and none of the gauges that run under the regulator are working. This is my 3rd one that ive put in.
Does anyone else know how I can reduce this any other way? I am pretty frustrated with changing these out.
Does anyone know the current passing through these or the amount of amps the gauges take?
If I knew this I could go with an electronic one which I hope would be more reliable.

Thanks in advance.

[rjewkes]

are they different between 67 and 72? i'm thinking they are.

[6T7Merc]

Alright so I did some research and I I decided to scrap the original moving parts version since ordering a new one from LMC would set me back another 30 bucks plus shipping. ( I am in no way trying to knock LMC. They make great original repos, but I decided to go my own way)
I took a trip down to my local electronics store and picked up the easy to find parts to do the same thing as the original moving parts did.
The whole thing cost me 13 bucks and with the number of parts that came with the packaging I had enough to make 3. Although i am sure one will last me the lifetime of the truck. It also fits right into the old regulator casing so it looks original!I put an optional LED on the side which lets me know if its working or not!

If anyone is interested Ill do a DIY so you can try it out if yours also blows!
Its very easy to make even if your not into that electronic stuff like I am.

[flyboy71]

I bet you snagged a pack of 7805 regulators at Ripoff Shack didnt ya? Either way let us know what you used and how much heat it generates.

[6T7Merc]

Ha! man, someone knows his stuff.
I did use 7805s but not from ripoff shack. Along with a 5v 1A LED and 1.0k ohm resistor. From what ive tested there is very little heat at all. I soldered the heat sync to the inside of the regulator casing itself to help dissipate heat even more so its not just the regulators heat sync doing all the work.

[6T7Merc]

So I got the the gauges working with the 5volt 1 amp 7805 regulator. I have one issue which has left me stumped though. All of my gauges have gone down a quarter of the way they normally read.
Does anyone know if this could be corrected by increasing either volltage and/or amperage?
I have an excellent ground so that can't be the issue. Any help woud be amazing

[flyboy71]

I never dinked around with the cluster in my truck when functioning so heres my hunch.... Im guessing the 5V from the regulator isnt really a steady 5V but a switched 12V under load. Because its a switched higher voltage and the meters are damped they indicate the average pulsed voltage from the regulator. If a steady 5V is fed to them you are getting the steady state reading, not the averaged reading from a switched source, hence it will be lower.

[6T7Merc]

Thats exactly what I was thinking flyboy. Do you think that if I up the voltage passing through to about 7 that it would put too much of a strain on the gauges?