6.0 FICM - How to adjust the output voltage [Archive] - TheDieselGarage.com

: 6.0 FICM - How to adjust the output voltage


bakantor
02-21-2010, 04:25 AM
Sorry all. I was hoping to do this back over a month ago.

Since there are many threads discussing how to get to and remove the ficm I will skip this. I'm starting with the assumption that you have the ficm apart and the power supply board is sitting in front of you.

This will be very straight forward because almost everything needed is in the pictures. I know I will forget something (because I'm distracted) so feel free to PM me if I don't respond to the thread in a timely fashion.

To start, here's a basic schematic showing the circuit you are working with. The actual power path (inductor, capacitors, fet switch and diode) are repeated 4 times on the board. However, there is only one feedback path which sets the output voltage.

http://www.thedieselgarage.com/forums/attachment.php?attachmentid=24686&stc=1&d=1266723821

The idea is simple... lower the value of the 2.15KOhm resistor by placing another resistor in parallel with it.

Here's a picture of the 7-screw ficm power board (If someone with the 4-screw model can post a picture that would be great). Please note, part values and names are the same for both variants and so is the general location of the parts (IIRC). I've crudely labeled the points you need to find and what I see as the best spot to make the modification.

http://www.thedieselgarage.com/forums/attachment.php?attachmentid=24685&stc=1&d=1266723821

The screw hole potentials (from left to right, listed as one row) are:

48V, 5V, (Not Determined), Ground, Ground, 12V.

That's about it! Install the adjustment resistor and you'll have your new voltage.

If you want something other than 58V (10K resistor) or 54V (20K resistor), you can find the necessary resistor value using the following equation:

R2 = 48.7 KOhm
R1 = 2.15 KOhm
Vout = Desired Output Voltage
Radd = Parallel resistor to R1 necessary to achieve Vout

Radd = (2.0295 * R2 * R1) / ((Vout * R1) - 2.0295 * (R1 + R2))

Thats it!

Cheers!
Brad

jello
02-21-2010, 07:47 AM
http://www.thedieselgarage.com/forums/picture.php?albumid=426&pictureid=3107

Extended Power
02-21-2010, 03:00 PM
This should be a "Sticky"!!!!

smokersteve
02-21-2010, 03:48 PM
How is this effecting the truck?

Dalpilot
02-21-2010, 03:50 PM
For those of us ......less electrically inclined, when you say put it on top, are yo literally soldering it on top, or in another location????

bakantor
02-21-2010, 04:58 PM
Literaly on top. Attach one side of the resistor to one end of the capacitor and the other end of the resistor to the other end of the capacitor.

A surface mount resistor is ideal because it will sit right on top and you just need someone to put some solder on each end. If you use a leaded component (classic resistor) you'll find the work much more difficult. You can get resistors from Digikey for next to nothing. Here's one example which will work.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=RHM10.0KCRCT-ND

These parts are somewhat small, so if you're not comfortable with this sort of work check with your friends... odds are someone has the capabilities to do the work.

Let's keep this thread as a "how-to". Take a look at the Swamps Hot FICM thread for pro/con discussion and real world performance. I think most of your questions will be answered there.

http://www.thedieselgarage.com/forums/showthread.php?t=90798

Cheers!
Brad

ricatic
02-21-2010, 05:19 PM
How about a finished picture showing the Digikey?

Ricatic

bakantor
02-21-2010, 05:32 PM
I thought I had forgotten to take a pic post-modification but I was wrong. This pic isn't the best but does illustrate placement of the resistor.

FYI, I used an even smaller resistor because I had it on hand. An 0805 size resistor like I linked to above would be easier to work with.

Cheers!
Brad

http://www.thedieselgarage.com/forums/attachment.php?attachmentid=24701&stc=1&d=1266773453

Wekiwa
02-21-2010, 05:55 PM
Great post Brad! Thanks! :rock
Folks can purchase a large self lit mag glass from Fry's electronics to help see those nano parts.

:txflag

Wekiwa

69cj
02-21-2010, 07:44 PM
Literaly on top. Attach one side of the resistor to one end of the capacitor and the other end of the resistor to the other end of the capacitor.

A surface mount resistor is ideal because it will sit right on top and you just need someone to put some solder on each end. If you use a leaded component (classic resistor) you'll find the work much more difficult. You can get resistors from Digikey for next to nothing. Here's one example which will work.

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=RHM10.0KCRCT-ND

These parts are somewhat small, so if you're not comfortable with this sort of work check with your friends... odds are someone has the capabilities to do the work.

Let's keep this thread as a "how-to". Take a look at the Swamps Hot FICM thread for pro/con discussion and real world performance. I think most of your questions will be answered there.

http://www.thedieselgarage.com/forums/showthread.php?t=90798

Cheers!
Brad

In other words your are creating an "RC" circuit.

bakantor
02-21-2010, 08:17 PM
Great post Brad! Thanks! :rock
Folks can purchase a large self lit mag glass from Fry's electronics to help see those nano parts.

:txflag

Wekiwa


Hahaha, Yeah, Fry's, Radio Shack, etc. I forget how small some of this stuff is because I work on components 1/4 this size at work. After awhile working on "large" parts like this becomes second nature and I can do it in my sleep :)

bakantor
02-21-2010, 08:22 PM
In other words your are creating an "RC" circuit.

Not exactly. The resistor divider (48.7K and 2.15K) create the feedback voltage for comparison. The C is there to filter out noise as you want a nice stable average (the RC is already there). You do move the filter pole by inserting an additional resistor, but you're really trying to reduce the bottom resistance from 2.15K to around 1.75K (for 58V if I recall correctly). By adding this resistor the filtering pole (and bandwidth) actually goes up albeit only slightly.

Adding the resistor forces the loop to increase the output to around 58 V to achieve the same 2.0295 V at the feedback node.

Brad

bakantor
02-21-2010, 08:33 PM
Looking at the other thread I modified this picture to show the location of the modification for a 4-screw FICM. The line indicates the easiest place to add the resistor.

Can someone "in the know" verify this is correct?

Thanks!
Brad

http://www.thedieselgarage.com/forums/attachment.php?attachmentid=24706&stc=1&d=1266784317

teamroper60
02-21-2010, 09:35 PM
Brad,

Since you have pics of the 7-pin, are the resolder points (for "fixing" a bad FICM) on the 7-pin or are they in different locations? And if they are different, can you point them out?

Thanks!
Chuck

UpstateDieselGuy
02-22-2010, 12:44 AM
Very Cool! The resistor that you linked to, do you just flow the solder to the sides? I've never worked with this style of resistor, only the wire style. Thanks in advance, Chris

Work&Play
02-22-2010, 11:36 AM
Thanks for the great info.

bakantor
02-22-2010, 11:46 PM
WARNING:

Check the voltage ratings on the large electrolytic capacitors. It has come to our attention different capacitors were used in different FICM builds. Here's what we do know:

1) 2003 7-screw FICM (mine) - 125 Volt Capacitors (OK for voltage upgrade).
2) Another 7-screw FICM - 63 Volt Capacitors... I would change out but it probably won't be the end of the world if you don't.
3) 4-screw FICM's to date - 35 Volt capacitors on the 12V input and 50 Volt capacitors on the 48V output :wtf. I would replace the output capacitors whether or not you do this mod!

bakantor
02-22-2010, 11:50 PM
Teamroper - The resolder points are essentially the same... I used the 4-screw pictures as a guide. Resolder all through-hole components (capacitors, inductors). Resolder the 7.5mOhm resistors on the bottom side of the switches. These likely say Dale on them. Be careful here... you need to be gentle yet get enough heat to reflow the joints.

UpstateDieselGuy - Yes, you just flow solder on each end. It will be clear when you get the resistor... there are metal pads on each end to connect to.

Cheers!

hpprose
02-23-2010, 01:02 AM
interesting

backwaterz
02-23-2010, 11:35 AM
bakantor,
you are saying to replace the input and and out put capacitors. i have a 4 pin ficm and does have 35v and 50v capacitors. as long as the they are the parts that are as big around a dime. what voltage should they be replaced with, and do i need to replace anything else if i do upgrade them??

Six_Leaker
06-22-2010, 05:27 PM
How many have had good luck with this mod. Any early 03 ficm's burn up yet with this mod?

Wesley00059
01-04-2012, 03:28 AM
Looking at the other thread I modified this picture to show the location of the modification for a 4-screw FICM. The line indicates the easiest place to add the resistor.

Can someone "in the know" verify this is correct?

Thanks!
Brad

http://www.thedieselgarage.com/forums/attachment.php?attachmentid=24706&stc=1&d=1266784317

I was wondering when replacing the factory resistors if you can use the round wire style found at radio shack

Wesley00059
01-12-2012, 01:05 AM
Sorry all. I was hoping to do this back over a month ago.

Since there are many threads discussing how to get to and remove the ficm I will skip this. I'm starting with the assumption that you have the ficm apart and the power supply board is sitting in front of you.

This will be very straight forward because almost everything needed is in the pictures. I know I will forget something (because I'm distracted) so feel free to PM me if I don't respond to the thread in a timely fashion.

To start, here's a basic schematic showing the circuit you are working with. The actual power path (inductor, capacitors, fet switch and diode) are repeated 4 times on the board. However, there is only one feedback path which sets the output voltage.

http://www.thedieselgarage.com/forums/attachment.php?attachmentid=24686&stc=1&d=1266723821

The idea is simple... lower the value of the 2.15KOhm resistor by placing another resistor in parallel with it.

Here's a picture of the 7-screw ficm power board (If someone with the 4-screw model can post a picture that would be great). Please note, part values and names are the same for both variants and so is the general location of the parts (IIRC). I've crudely labeled the points you need to find and what I see as the best spot to make the modification.

http://www.thedieselgarage.com/forums/attachment.php?attachmentid=24685&stc=1&d=1266723821

The screw hole potentials (from left to right, listed as one row) are:

48V, 5V, (Not Determined), Ground, Ground, 12V.

That's about it! Install the adjustment resistor and you'll have your new voltage.

If you want something other than 58V (10K resistor) or 54V (20K resistor), you can find the necessary resistor value using the following equation:

R2 = 48.7 KOhm
R1 = 2.15 KOhm
Vout = Desired Output Voltage
Radd = Parallel resistor to R1 necessary to achieve Vout

Radd = (2.0295 * R2 * R1) / ((Vout * R1) - 2.0295 * (R1 + R2))

Thats it!

Cheers!
Brad

So I just replaced all four resistors and my truck still won't start any ideas

Wesley00059
01-12-2012, 01:06 AM
I just replaced my resistors and still won't start any ideas