datzenmike Posted June 19, 2015 Report Share Posted June 19, 2015 Many discoveries have been found by several independent sources at the same and differing times. If there is a need for something and a good remedy it's only reasonable will be found. Sometimes several times. 1 Quote Link to comment
XXL Posted June 19, 2015 Author Report Share Posted June 19, 2015 OK, ready to install. I sure hope that's the actual problem my gauges are having :geek: Parts (including spares... Murphy's law hits hard around here)-- Oops... skipped a few progress pics. Here it is with caps and leads soldered and each lead heatshrinked. Because the center lead on the LM7809 is chassis ground, it doesn't need a lead because the metal tab on the other end will serve as the ground when I screw it to the back of the IP where the factory "regulator" was grounded. The caps are parallel across 1-to-2 and 2-3 to level off the voltage bounce.-- And then .187 male spades on the ends of the wire leads, then one overwrap of shrinkwrap tubing to pretty everything up-- Here's reference voltage coming straight off the truck's battery terminals-- And finally, here is Vo-- When I rev the engine, I get about 13.8V at the battery, but the regulator keeps an exact 9.00V. 1 Quote Link to comment
XXL Posted June 19, 2015 Author Report Share Posted June 19, 2015 And... gauges are working again. I'll top off the gas tank later when I go out to make sure I didn't muck up the calibration on the gauge. Thanks all for the input on this. It was a fun fix, actually. Also, if anyone has a need for one of these, I have some spare parts. PM me. 1 Quote Link to comment
datzenmike Posted June 19, 2015 Report Share Posted June 19, 2015 Not sure the correct voltage... about 8? Either way always less than an idling alternator so the gauges don't fluctuate at ide too. If 8 or 6 and you have 9 they may read a little higher than intended??? 1 Quote Link to comment
XXL Posted June 19, 2015 Author Report Share Posted June 19, 2015 It was a fun fix, actually. And it worked... For half of my quick trip to the store. After coming back out, it is dead again. So... will have to take it back apart to see what failed. Maybe bad solder joint (the looked and felt fine), or the transistor itself failed (seems low probability). Or... It has now moved beyond "fun fix." :poop: 1 Quote Link to comment
zed1 Posted June 19, 2015 Report Share Posted June 19, 2015 I have a spare instrument panel (from a 521) if you want to test your sending units with it. Keith 2 Quote Link to comment
XXL Posted June 19, 2015 Author Report Share Posted June 19, 2015 I have a spare instrument panel (from a 521) if you want to test your sending units with it. Keith Thanks for the offer. If I dig into it and can't find the problem, I'll give you a shout. I'm hoping it's just a bad solder joint or something similarly silly of me. I should have made the leads about 1" longer. As they are, there's a tiny bit of tension on them once plugged in. That could have caused something to pull loose. :frantics: 1 Quote Link to comment
Charlie69 Posted June 20, 2015 Report Share Posted June 20, 2015 XXL Are you in Texas? Never seen any one use the caps as you did. Lengthen your wires and check to see if rivet is tight. If needed replace rivet with a machine screw with a nyloc nut. I have a few instrument clusters if you want a spare. Quote Link to comment
datsunrides Posted June 20, 2015 Report Share Posted June 20, 2015 When you have it back out, check the continuity along the printed circuit. These are pretty old and prone to breaking. My 521 had a problem with the temp gauge and it turned out to be a break in the printed circuit. Sometimes it worked, others it didn't. Little bit of solder fixed it. Mark 1 Quote Link to comment
XXL Posted June 20, 2015 Author Report Share Posted June 20, 2015 XXL Are you in Texas? Never seen any one use the caps as you did. Lengthen your wires and check to see if rivet is tight. If needed replace rivet with a machine screw with a nyloc nut. I have a few instrument clusters if you want a spare. Yes, but don't hold that against me :console: . The caps are there to reduce ripple in the output... probably not necessary, since the transistor is already light years cleaner output power than the "regulator" that it replaces. Rivets are clean and tight, and I'm seeing zero drop across all ground points. I may hit you up about a spare anyway. Thanks. When you have it back out, check the continuity along the printed circuit. These are pretty old and prone to breaking. My 521 had a problem with the temp gauge and it turned out to be a break in the printed circuit. Sometimes it worked, others it didn't. Little bit of solder fixed it. Mark There were some trace repairs done by a PO (maybe boxboy? I saw a thread where he was discussing problems after swapping in some 5w bulbs into the 3w circuit). Those aren't very pretty but they are electrically solid. I just pulled it apart again to see if something obvious might have gone bad... and yes, it was a simple transistor failure. So much for second guessing my solder joints. They were fine. I have another transistor (Murphy's law told me to buy 2), so I'll try again. If this one fails, I'm concerned that the gauges are pulling more than the 1A rating of the transistor... though others have reported using this same transistor successfully, so I'm betting I just had a random failure. However, if the second one dies, I might build a circuit using an LM338, which has a 5A rating. It's a little different design in that it has a variable output, which you can tune with a resistor. The simple method would be to just hit the right value resistor and be done. Or, you can add a varistor and tune the voltage on demand until I get it exactly where I want (9v? 8.6v? ... I've seen both mentioned in other discussions). Once I get the voltage output, you just toss a dab of hot glue on the varistor so it doesn't move on you. We'll see. 1 Quote Link to comment
Charlie69 Posted June 20, 2015 Report Share Posted June 20, 2015 PM me you address and I will send you a working used voltage regulator for test purposes or use. This way you can determine actual required voltage. Have you tested your gauges and have you tested sending units and wiring. All are over 40 years old. If you loose another transistor I would look at what is causing the amperage draw. 1 Quote Link to comment
XXL Posted June 20, 2015 Author Report Share Posted June 20, 2015 PM me you address and I will send you a working used voltage regulator for test purposes or use. This way you can determine actual required voltage. Have you tested your gauges and have you tested sending units and wiring. All are over 40 years old. If you loose another transistor I would look at what is causing the amperage draw. Actually the very first thing I tested was the sending unit because I didn't notice the temp gauge was also not working... and because it's so easy to get to through the trap door on the bed (that almost everyone who comments on the truck seem to ask about). It was fine... IIRC, about 50ohms at the time, and bounced around when I shook the truck to slosh the fuel around. I have not tested the temp sender... because it wouldn't explain why both gauges died. However, that's also an easy task so I might as well do that next time I'm out in the garage. If the second transistor dies, then there is, as you say, likely a current draw issue. I can't imagine those 2 gauges would pull more than 0.25A on their worst day. And, since others are using this same transistor to fix, it means others aren't drawing more than 1A or their transistors would be dying as well. 1 Quote Link to comment
thisismatt Posted June 20, 2015 Report Share Posted June 20, 2015 I thought someone who was using the LM7809 noted high/hot temperatures? Maybe I'm imagining things. Would be a concern in a hot car environment, though. 1 Quote Link to comment
XXL Posted June 27, 2015 Author Report Share Posted June 27, 2015 Round 2... I built the circuit again, this time with longer leads and a heat sink. I included a ground lead (capped off in pic) in case I want to get a better ground than the stock screw ground. Just as the first one, this one works fine on the bench. Hopefully all it needed was a little bit of heat sink to fix. Otherwise, :poop: 1 Quote Link to comment
XXL Posted July 2, 2015 Author Report Share Posted July 2, 2015 PM me you address and I will send you a working used voltage regulator for test purposes or use. Hey, Charlie... where'd you go? Check your PMs :poke: 1 Quote Link to comment
XXL Posted July 4, 2015 Author Report Share Posted July 4, 2015 Hey, Charlie... where'd you go? Check your PMs :poke: Where'd you go? Board says you've been online... check your PMs. 1 Quote Link to comment
Charlie69 Posted July 4, 2015 Report Share Posted July 4, 2015 Sent you a PM. Been down hurt my back. and I forgot sorry for the inconvenience. Quote Link to comment
XXL Posted July 7, 2015 Author Report Share Posted July 7, 2015 I'm just posting an update to jinx myself... 4 days working (so far)... I figure as long as I leave the plastic trim piece off, and thus the truck is "apart," it'll work just fine. Of course, as soon as I button it all back up, there'll be a problem (see Murphy's Law). Charlie69 is sending me a spare IP just in case. 1 Quote Link to comment
DanielC Posted July 7, 2015 Report Share Posted July 7, 2015 Come on, two clips, and two screws. Put the plastic trim back on. Have some faith in yourself! 2 Quote Link to comment
XXL Posted July 22, 2015 Author Report Share Posted July 22, 2015 Dammit! No, the tank is not overflowing. No, the engine is not melting into a pool of steel. Yes, I am driving 55 down the road. 1 Quote Link to comment
Charlie69 Posted July 23, 2015 Report Share Posted July 23, 2015 What are you doing? I checked both VRs before I sent them to you. Quote Link to comment
XXL Posted July 23, 2015 Author Report Share Posted July 23, 2015 What are you doing? I checked both VRs before I sent them to you. That's the existing setup with transistor VR. I haven't done anything but drive it. Going to pull it out "soon" to try to figure out the issue once again. 1 Quote Link to comment
Charlie69 Posted July 24, 2015 Report Share Posted July 24, 2015 Are you still using the patched PC board? Quote Link to comment
XXL Posted July 24, 2015 Author Report Share Posted July 24, 2015 Are you still using the patched PC board? Yeah, I haven't done anything yet with any of the parts you sent. Too hot, too ill, too ambivalent at the moment :poop: . It's on my to do list... maybe tomorrow I'll pull the IP and start to debug the issue. 1 Quote Link to comment
Charlie69 Posted July 25, 2015 Report Share Posted July 25, 2015 I suggest put the cluster in that I sent you complete untouched and see what happens. I think that your circuit board may be bad. The over of an extra circuit board still stands if you need it. Quote Link to comment
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