Instrument cluster voltage regulator upgrade

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67GMC
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Re: Instrument cluster voltage regulator upgrade

Post by 67GMC »

Thanks so much and I appreciate the offer a great deal
I've got it back in right now the old way (with RFI shunt installed) and no USB attached. I wanted to check it again now that I have the connections nice and shiny. All the lights work, dim etc, fan works, seatbelt light come on, ammeter working but I now have no gauges at all! I had oil and temp before. The IGNLPS fuse is blown so must have something on wrong. At least its sunny out now. About 45F yesterday so a little chilly outside. Today is nicer. One step forward and three steps back!
My Stable:
1984 Jeep Grand Wagoneer, 360 V8, Auto, SelecTrac
1987 Jeep Cherokee (XJ), 4.0L I6, Auto, Selectrac
And a few more....
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67GMC
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Re: Instrument cluster voltage regulator upgrade

Post by 67GMC »

OK-Fixed the issue with the IGNLPS fuse. The coolant gauge must have been touching the metal back plate. So, everything is working except fuel gauge (argh!). I'm going to run a line directly from the fuel sender to the back of the gauge cluster.

Question: What voltage should be present at the sender? Is it 5V from the CVR or 12V?

Right now, the fuel sender seems to have the right OHMS for the fuel in the tank but there's no voltage at the pink wire (and no short to ground either). Internal resistance for the gauges is on spec with the FSM (about 21 OHMS).

I made new ground wire for the sender and no difference there. I'm thinking if I run a new wire from the pink wire off the octal socket to the sender it would bypass the harness and I should be able to read the voltage at the send and the gauge should work too.

Fuel gauge works properly when you follow the method specified in the FSM. I can get the gauge to move electrically so not a gauge issue and CVR is ruled out as coolant gauge and oil pressure are both working fine. Puzzled on this. It was working until I had a major electrical issue in the spring.

Ideas to try?
My Stable:
1984 Jeep Grand Wagoneer, 360 V8, Auto, SelecTrac
1987 Jeep Cherokee (XJ), 4.0L I6, Auto, Selectrac
And a few more....
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tgreese
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Re: Instrument cluster voltage regulator upgrade

Post by tgreese »

The CVR is pulse width modulated (on-off-on-off continuously, averaging out to about 5V) so it's hard to predict what you'll measure at the gauges. Much depends on the quality and characteristics of your meter. Ideally, your meter would be so fast that you'd see it flash between 12-13V and 0, but the DC volts setting on a hand multimeter may show an average or may freak out and never show you a reading. If you have an old-fashioned analog meter, that will probably show you something reasonable, like the needle wobbling around 5V

Note that the CVR is connected to your temp and oil pressure gauges as well, so if those worked, I would presume the CVR is working. Again, you can test these other gauges with the resistances shown in the TSM.

Before connecting directly to the sender, I'd measure the resistance to ground at the sender. The gauge should show that level, since the resistance from the sender base through the body back to the battery should be tiny, like a fraction of an ohm. This is something else you could measure.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
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67GMC
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Re: Instrument cluster voltage regulator upgrade

Post by 67GMC »

So, first clue was that the Temp and OIl Pressure were working but the fuel gauge didn't indicate what the fuel sender was sending. As Sherlock Holmes would say, once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth. So, in my case, it was impossible that the gauge didn't read the fuel level since Oil and Temp were working and Fuel gauge electrically worked too. The improbable was that I assumed that the pink wire was on the L terminal of the octal connector but some idiot had put it on the B terminal when he repaired the shorted wire some time before. The thing is, the B terminal looks like the L terminal if you're looking up at it instead of down at it. Guess who did that???

Anyway, all working and I can now know how much fuel is in the Jeep. I had about 1/16 of a tank to get to the gas station so I made it and filled up this afternoon.

Thanks for the help Tim!
My Stable:
1984 Jeep Grand Wagoneer, 360 V8, Auto, SelecTrac
1987 Jeep Cherokee (XJ), 4.0L I6, Auto, Selectrac
And a few more....
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tgreese
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Re: Instrument cluster voltage regulator upgrade

Post by tgreese »

Glad I could help!
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.

letank
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Re: Instrument cluster voltage regulator upgrade

Post by letank »

tgreese wrote: Thu Apr 30, 2015 3:21 pm
The capacitors on the input and output have similar purposes. Ci on the input side smooths the input voltage, protecting the device from any voltage spikes or high-frequency noise from the power supply.
I skipped on the Ci and indeed, I started to get some high frequency sound on the AM/FM/CB radio some time ago after I installed it... So in case someone read this post, install the ci capacitor. Will post when installation done. Of course with radio check gone... anything has to be ordered
Michel
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tgreese
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Re: Instrument cluster voltage regulator upgrade

Post by tgreese »

Oscillation turns the wires into radio broadcast antennas. Surprising.

Just move Co to Ci. It'll be fine.

Looks like the Fairchild data sheet on the first page is gone, taken over by ON Semi. Here are some alternatives -
https://www.mouser.com/datasheet/2/308/ ... 773680.pdf
https://www.mouser.com/datasheet/2/258/ ... 626349.pdf
https://www.mouser.com/datasheet/2/308/ ... 878886.pdf
https://www.mouser.com/datasheet/2/389/l78-1849632.pdf
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.

letank
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Location: SF bay area

Re: Instrument cluster voltage regulator upgrade

Post by letank »

tgreese wrote: Wed Jan 06, 2021 7:20 am Oscillation turns the wires into radio broadcast antennas. Surprising.

Just move Co to Ci. It'll be fine.
I did today, but it is still broadcasting a high pitch, but a cleaner one ... so no need to redo another attempt with the proper Co cap, according to the docs you sent, it is not needed.

Thank you for your knowledge

I guess I need a new radio! or test with another one. The high pitch disappear when the volume is lowered to barely on , or 1/4 of the volume course.
Michel
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85 Gwag (229 Kmiles... the running test lab)
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tgreese
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Re: Instrument cluster voltage regulator upgrade

Post by tgreese »

You're welcome to my help, though I'm sorry my suggestion did not work. A capacitor on the input should dampen any oscillation. The app notes say that Co only affects the responsiveness of the circuit, not stability.

Suggestion - disconnect your antenna wire at the fender. Then make a loop of wire on the end of the cable and use it like a probe. You should be able to localize the source of the noise with your improvised probe.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.

letank
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Re: High pitch sound

Post by letank »

tgreese wrote: Thu Jan 07, 2021 4:44 pm Suggestion - disconnect your antenna wire at the fender. Then make a loop of wire on the end of the cable and use it like a probe. You should be able to localize the source of the noise with your improvised probe.
Disconnected the antenna and could not find anything! BUT, after reinstalling the antenna plug (I had to use a different antenna cable because now I have the indoor antenna)... the high pitch noise is gone... until next time
Michel
74 wag (349 Kmiles... parked, next step is a rust free body)
85 Gwag (229 Kmiles... the running test lab)
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altayd9
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Re: Instrument cluster voltage regulator upgrade

Post by altayd9 »

I keep having a problem with the transistor. I’ve been using a 7806. This is the 2nd one I’ve installed, both of them seem to have burned out. Anyone else have this problem or have I done something wrong?
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tgreese
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Re: Instrument cluster voltage regulator upgrade

Post by tgreese »

It's not a transistor - it's an integrated circuit, containing many transistors and other electronic parts. A very rugged component. If you connect it wrong, it will shut down, not burn up. How are you connecting it? Where did you get the part, and what brand is it?
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.
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altayd9
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Re: Instrument cluster voltage regulator upgrade

Post by altayd9 »

I connected it just like letank, earlier in the thread. I bought it off of mouser, I think it’s from ST. When I first replaced it I noticed the capacitor legs soldered in the middle came undone, does it get that hot?
I was suspecting maybe my battery is weak and when I tend to crank it a lot once it starts the ammeter pulls a lot of current so maybe the chip gets too much current from somewhere?
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tgreese
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Re: Instrument cluster voltage regulator upgrade

Post by tgreese »

ST Micro is a quality maker. Parts from Mouser will be genuine, not counterfeit.

Possible it could get that hot if you connected 12V to the center grounded lead. Most of these chips have a metal tab, and it's connected to ground. If you connect power to the center lead and the tab is on the cluster steel housing, you are grounding that wire.

A short will get hot but it won't ruin the chip. Suggest you test the chip on the bench. You can use a light bulb as a load.

https://www.mouser.com/datasheet/2/389/ ... 795274.pdf Pinout is shown on figure 3 here.

Look at page 1L-46 here. https://oljeep.com/gw/82_tsm_2/82Wagone ... rPlant.pdf

Remove the jumper between pins 14 and 15. Pin 11 or 14 to Vin. Vout to A1, A2 or A3. Ground the chip either by mounting the metal tab on the cluster steel, or by running the ground pin to another ground on the cluster.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.
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altayd9
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Re: Instrument cluster voltage regulator upgrade

Post by altayd9 »

I tested the old one on the bench with a 12v wall plug, when I apply 12V to input, it fails to output 6V, it sure seems like the chip is ruined.
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tgreese
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Re: Instrument cluster voltage regulator upgrade

Post by tgreese »

There are three pins, in out and ground. The metal tab is connected to ground. Did you ground the center pin to the negative of the power supply? Did you put a load between out and ground? Your meter may not be enough load so the chip regulates. I would put the meter across a load, maybe a resistor or a bulb.

It's possible that the IC (chip) is broken, but it seems very unlikely. They have existed for decades, and are designed to resist accidents. You could potentially kill it with a power supply voltage above its maximum (ca 35 volts). Static discharge could kill it too, but you'd have to give it a real jolt, I'd think. I've never had a problem with static with simple parts like this.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.
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tgreese
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Re: Instrument cluster voltage regulator upgrade

Post by tgreese »

This is a 7805, but that's all I had on hand -
7805test.jpg
It's 2.2% under-voltage; not bad. The resistor is 340 ohms and that's nearly 70 mA - a lot to be drawing from that little battery. Tested that cheap meter against my Fluke bench meter and it's right.

Don't know how savvy you are about this stuff, but this is how you would test the IC. This is junk I have on my bench. The clip leads make it easy, and are something good to have. You can use any load you like; I suggested something like a taillight bulb from your Jeep.
You do not have the required permissions to view the files attached to this post.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.
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altayd9
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Re: Instrument cluster voltage regulator upgrade

Post by altayd9 »

I’ll try with a load, 12V+ was connected to input and 12V- was connected to the middle ground and output was measured with one lead on the ground and the other on the output. When I tested my second one before putting it in using the same method, it did output 6V like it should.
'85 Grand Wagoneer and '96 LS400

marc
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Re: Instrument cluster voltage regulator upgrade

Post by marc »

As one who is electronically ignorant at this level, how do you heat sink the 7806 assembly to the speedometer housing?
J10 1984, very stock with AMC 258.
Truck appears to have been rebuilt or restored at one time
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tgreese
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Re: Instrument cluster voltage regulator upgrade

Post by tgreese »

If you mount the IC on the steel part of the cluster (as shown above and here), you don't need a heat sink.

Image

Some have used the screw on the back of the speedometer case to mount the IC. Or you could make a bracket for the IC, and mount the bracket under that screw. Lots of options. You'd only need a proper electronics-type heat sink if the IC were mounted in mid air, and maybe not then. The gauges don't sink a lot of current.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.
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