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V1 Brad's City Goblin - 10 SS/TC Donor, NY Build - FOR SALE

ctuinstra
Briann1177 said:
What's the forward voltage on those LEDs? 2.9V.

R = E/I
(3.3 - 2.9)/.27
1.5 ohms

P=IE
P=.27 * (3.3 - 2.9)
P = .108W

If my math is correct and thinking along the same lines as Brad.
Click to expand...
That is all correct but the biggest issue it getting the input voltage (13.8v) down to 3.3v while passing .270A. So there is 2.8W of power that has to be used or dissipated as heat. That's terribly inefficient.


Briann1177 said:
P=IE
P=.27 * (3.3 - 2.9)
P = .108W
Click to expand...
This is calculating the power dissipation for the current limiting resistor, not the entire circuit. Even at a 1/4w, I'll bet it still gets a bit warm dissipating .108w.
 
B
How do you figure 2.8W? The dissipated power basically will remain the same on both the input/output side. You do have to factor in a bit of loss due to the efficiency of regulator but even at 50% efficiency, that's still barely a 1/4W of input power.

Think of it this way. If you run your 240V compressor off 120V, the consumed power will remain the same, but the current will double.
 
B
Net result of my testing - the linear regulator worked but got warmer than I liked for being placed inside the cluster as ctuinstra previously found. I ended up using a cheap chinese buck converter that drops the battery voltage to 3.3 volts and then 1.5 ohms worth of resistors. The buck converter is rated at 3 amps (way overkill) and does not generate any heat.

I only had to cut one trace and trim some of the plastic on the back cover of the cluster to fit the buck converter. The lighting looks amazing and was totally worth the effort.

12894


12895



The light leaking out behind the needles is because they are not pushed on all the way.
12896
 
ctuinstra
bradr said:
Net result of my testing - the linear regulator worked but got warmer than I liked for being placed inside the cluster as ctuinstra previously found. I ended up using a cheap chinese buck converter that drops the battery voltage to 3.3 volts and then 1.5 ohms worth of resistors. The buck converter is rated at 3 amps (way overkill) and does not generate any heat.

I only had to cut one trace and trim some of the plastic on the back cover of the cluster to fit the buck converter. The lighting looks amazing and was totally worth the effort.
Click to expand...

Love it! I wish I would have thought of the buck converter when doing mine. Eh, either way works, yours is easier to do.

Sure does put the old filament bulbs to shame!

It's hard to get a good picture of how they really look. So much better in person.
 
B
ctuinstra said:
Love it! I wish I would have thought of the buck converter when doing mine. Eh, either way works, yours is easier to do.

Sure does put the old filament bulbs to shame!

It's hard to get a good picture of how they really look. So much better in person.
Click to expand...
You are not wrong, they look way better in person. I can't believe the improvement. Thanks for doing the legwork on this one!
 
Ross
Ever since I saw Chad's dash, I have wanted to do this. Way better than stock.
Nicely done, Brad.
 
B
Did you use the pad that corresponds to pin 8 on the cluster connector for you voltage converter input?

Also curious to know what trace(s) get modified. Do you have a schematic for the cluster board?
 
B
Briann1177 said:
Did you use the pad that corresponds to pin 8 on the cluster connector for you voltage converter input?

Also curious to know what trace(s) get modified. Do you have a schematic for the cluster board?
Click to expand...

**I did not take pictures of what I did, so I stole a picture from ctuinstra to mark up what I did. This picture is only for reference - please ignore the wires and resistor. Because there was a wire in the way of one of the traces, I represented the trace by the yellow lines.**

Parts used:
  1. (6) LEDs found HERE
  2. (1) Buck converter found HERE
  3. (1) 1.5 ohm 1/2w resistor
Procedure:
  1. Desolder old bulbs carefully as to not damage the pads on the board.
  2. Solder in the LEDs - see my previous post HERE about orientation and shifting the LED as to not short the cathode.
  3. Cut the trace as shown in picture below
  4. Trim out the plastic reinforcements on the back cover of the cluster to clear the height of the buck converter.
  5. Glue the buck converter to the back of the circuit board.
  6. Solder in buck converter to the points shown in the picture below. Both grounds go to the same point.
  7. Enjoy!
Notes:
  1. You can use a 1/4w resistor, I wanted to play it safe.
  2. You can use a combination of resistors to tune the current or if you do not have exactly 1.5 ohms.
  3. 1.5 ohms was used to target 45mA per LED of the 60mA max they can handle.
  4. There are MANY buck converters that will work, many smaller. This one is way overkill, but it was cheap and already in an enclosure.
  5. You will no longer be able to dim the cluster - I would recommend removing and shorting the dimmer wires in the car.
  6. I am guessing this buck converter is not isolated, but assuming it is, attaching the two grounds together like I did would remove any isolation that the buck converter might have provided. There is no safety or electrical reason in this application to require isolation.
Picture for reference only - see notes above.
12912



Actual picture of my cluster after modification - the three 1 ohm resistors equal 1.5 ohms in this configuration.
12916



Back plastic trimming.
12913
 
Last edited:
Ross
bradr said:
**I did not take pictures of what I did, so I stole a picture from ctuinstra to mark up what I did. This picture is only for reference - please ignore the wires and resistor. Because there was a wire in the way of one of the traces, I represented the trace by the yellow lines.**
Click to expand...
I need this guide to follow.
So thankful to Chad and Brad for forging the way on this!
 
B
Good news: I figured out how to reset the odometer in the BCM.

Bad news: The current method I am using requires the BCM to be opened up to directly access the EEPROM and is not DIY.

So far I can reset the mileage to 0, but can't enter a specific value. There is some black magic going on inside the BCM related to mileage and may be encrypted, formula driven, or I might just be too dumb to figure it out at first glance. All that said, it is not worth my time to reverse engineer it. Other things I can edit are the VIN stored in the BCM and the BCM serial number.

12966



My testing platform:

12967
 
ctuinstra
I'd like to least turn it back to when we finished the car. Missouri just passed a new law and now the Motor Vehicle Safety Inspections are only required on vehicles over 149,999 miles. I don't want to have to take it in to get it inspected any sooner than I have to.
 
TheNuker
ctuinstra said:
I'd like to least turn it back to when we finished the car. Missouri just passed a new law and now the Motor Vehicle Safety Inspections are only required on vehicles over 149,999 miles. I don't want to have to take it in to get it inspected any sooner than I have to.
Click to expand...
Yeah exactly, I would like to start at zero with the new engine/trans.

Nuker-
 
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