PSD Electaical Signals Analysis

[GARY PAGE]

PSD Electrical Signals Analysis
Well I am on mission to learn how this gismo works or at least understand the stalling situation. My questions are for a few of the tinkers with EE backgrounds in the bunch and you need a service manual on electrical diagnosis to follow me. Has anyone looked at the bias signal at the PSD pin D to ground Pin F and Engine Ground, are they noisy? Has anyone tried a filter say 100 uF tantalum cap with 0.01 in ceramic in parallel at the PSD on between pin D and Pin F to filter the bias signal. Looking at the Fuel Shut off solenoid depending on the level of signal BC16 from the ECM ( the other side of the solenoid winding) there may be some tendency for DI/DT to occur as a result of variations in bias the other side of the Engine Shut Off Solenoid coil, resulting in added whips to the bias signal. I don

[turbovair]

Gary,
Im glad to hear someone else thinks there's more to it than heat.You may be on to something here.I wish I could comment but I'm only a turbine engine mechanic, not an electrical engineer.

[ucdavis]

Gary,
My scantool supposedly does scope readings but I have no idea what you're looking for (nomenclature is way foreign). I'll shoot you an email and if I can get an understanding of the measurements, maybe I can give you some data that would be meaningful.

[GARY PAGE]

Yes I wish I had not misspelled Electrical in the title block, doesn

[Turbine Doc]

Gary,
While not a tron tech by training, (I was trained as a turbine mechanic also; on turbine powered ships) I had to learn about trons a bit, to defend the ever popular battle of it's electrical/it's mechanical not my problem battle. In my world now "it's broke Mr. GE Rep. what are you going to do about it", I still have same battle but now, is it a GE problem or a control vendor problem.

Anyway I have access to a O scope tell me what you are after and I'll see what I can come up with, are you suspecting "noise" causing extra excitation of the PMD transistors, and wanting to put a cap in the circuit to filter it out? Get with MP for my details and we can talk off forum until we come up with something (this could get lengthy) and post noteworthy results as, or if, we "fix it".

[moondoggie]

Good Day!

If you are going to research this off-forum, is there any way I could be included? I was at one time an Electronics Tech., although I couldn't get a job in that field now. The only reason I haven't already gone the direction you'd like to go is TIME. I had a dead FSD sitting on my desk for a couple years until I realized I probably wasn't ever going to be able to do what I'd like to do.

Thanks & Blessings!

Brian Johnson, #5044

[StephenA]

Hi Guys'
I'm a fair electronics hack myself. How about we scrounge up a bunch of the old discarded units, power up & compare them with a working unit, and find out what's failing on them.? Can't be that tough...
Gary -did you get noise before ignition/alternator spin-up? If so, from where? Batteries are dead quiet...

[Turbine Doc]

All, My suggestion to off line wasn't to exclude anybody, all help is welcomed I just didn't want to tie up forum space, during the investigative process, any of you computer types know of a good place to start a chat room on this in real time, email tag could slow us down, plus any interested parties could join the discussion.

Kennedy you got any donor discards for di-section

[StephenA]

I'm in, chat room or no. If my 92 wasn't mechanical, I'd scope each pin on a running unit and see exactly what this thing is doing & when. We could start with a connector which the unit piggy backs on to, that has parallel leads running off each pin. I'm curioius about the noise Gary found, & what the signal to noise ratio is (not to mention where it comes from if the engine isn't turning & it's still there).
Seems like folks have been grinding away potting material with no luck. If someone will send me a bad unit, I'll get my dentist to xray it & post the pics... Let's crack this sucker!

[gmctd]

Pin D is Fuel Solenoid Driver power from the battery - the parallel 20amp 120v PNP pair pulls the Fuel Solenoid up to +12v thru this pin.
Parallel devices are required to handle the 40amp solenoid draw.
Emitter 'resistors' are laser-trimmed steel bars.
Pin F is Battery Neg common, engine ground, which is fed to the driver in the PCM via pin C, such that ground loop current is avoided.
A reverse blocking diode handles high emf spikes, but could be breaking down from constant ignition switch cycles and hot-soak
Same reverse-emf would also damage other electronic devices on battery power - Map and Boost sensors, PCM, instrument cluster (yep - it's all electronic now), Radio, etc.

The 'replaced the PCM cured the problem" could hold water - possibly the reflash and relearn let the replacement PCM adjust to deteriorated Drive FI Signal feedback characteristice.

We had found oem deteriorated Bi-polar specs would not run in our switching power supplies, and had to redesign for FET devices to ship reliable units. The bi-polar transistors would pass static tests, but fail switching tests.
This happened with no warning in the mid-'90s.

Logic circuitry in the FSD is regulated down, preventing solenoid switching noise interference.

jd

[turbovair]

Good idea, X-raying the box. Will it provide enough detail to help?
What about dissolving the potting material somehow? I know its tough stuff, but somewhere on this planet there has got to be something that will do it without destroying the electronics.

[turbovair]

Remember on the older Fords right around the time they incorporated electronic ignition? The dreaded "silver module" on the firewall? Those used to fail randomly causing stalling of the engine. You had to always carry a spare. Somebody worked the bug out of those. Maybe it was "Bluestreak" who got involved and fixed Fords screwup by offering an aftermarket part.

[StephenA]

Never saw anything that would eat potting material, but with an x-ray or map, it's usually not to hard to dremel down to the actual traces & components. The tough part is getting the part numbers, but if it's just an amp, that doesn't matter. If we could monitor both input & output, we'd know what it is.

[moondoggie]

Good Day!

Might it not be a good idea to somehow combine VERY DISAPPOINTED WITH FSD DRIVER / COOLER & PSD Electaical Signals?

Blessings!

Brian Johnson, #5044

[turbovair]

Lets launch a new thread."Solving the mystery of the PMD/FSD"? Or,"lets solve the PMD/FSD problem once and for all"??

[vernj4]

I understand the military has 6.5 L powered vehicles. If this is so,do they have the same problems..............or as the "supplier" solved their problem?

Any guys or gals in the service involved with or know someone who works on 6.5L powered vehicles?

[ucdavis]

MilSpec version is mechanical injection. They no dummies.

[BUZZ]

So Tim the trubine tech, were you on Perry class Frigates or Spruance class Destroyers.
Buzz a Perry Class GSE.

[tom.mcinerney]

Gary- 1.)Sorry your rig's not running too well!
2.) The above post (10/29/03 11:37A.M.) by gmctd(member#1505, aka 'jd') is the second he's contributed in past year, indicating privileged familiarity with the FSD/PMD.
In a recent posting More Power indicated that the engineer responsible for the remote FSD Cooler has been attempting to devise a replacement driver assembly using mil-spec/aerospace components. This patient soul is known as:
Christer Lindstrom, BETA
Beta Maskin AB
Hogboleden 28
774 61 Avesta, Sweden
Phone no: 011 46 226 54070
Fax no: 011 46 226 50757
e-mail: mail@betamaskin.se
Perhaps you could communicate with these folks....
Many of us comprise an avid, willing audience for these efforts!

[Turbine Doc]

Buzz,
Neither, Kidd aka(Ayatollah)Class
DDG-995 USS-Scott

When did you go thru the pipeline at the Lakes I was 80-81, Active 80-85 USNR 86-97 GSMC(SW) when I left

[StephenA]

Originally posted by StephenA:
</font><blockquote>quote:</font><hr />Originally posted by gmctd:
Pin D is Fuel Solenoid Driver power from the battery - the parallel 20amp 120v PNP pair pulls the Fuel Solenoid up to +12v thru this pin.
Parallel devices are required to handle the 40amp solenoid draw.
Emitter 'resistors' are laser-trimmed steel bars.
Pin F is Battery Neg common, engine ground, which is fed to the driver in the PCM via pin C, such that ground loop current is avoided.
A reverse blocking diode handles high emf spikes, but could be breaking down from constant ignition switch cycles and hot-soak
Same reverse-emf would also damage other electronic devices on battery power - Map and Boost sensors, PCM, instrument cluster (yep - it's all electronic now), Radio, etc.

The 'replaced the PCM cured the problem" could hold water - possibly the reflash and relearn let the replacement PCM adjust to deteriorated Drive FI Signal feedback characteristice.

We had found oem deteriorated Bi-polar specs would not run in our switching power supplies, and had to redesign for FET devices to ship reliable units. The bi-polar transistors would pass static tests, but fail switching tests.
This happened with no warning in the mid-'90s.

Logic circuitry in the FSD is regulated down, preventing solenoid switching noise interference.

jd </font>[/QUOTE]jd:
Ok so the PNP parallel pair of transistors represents almost 500 watts of amplifier (12v X 40 amps). If so, that's some juice; the power supply wiring must be rather hefty. A 500 watt amp with no oem heat sink seems strange, despite the laser trimmed steel bar resistors (which are used becuase of their ability to handle heat, no doubt, or was it also for accuracy?).
Ground loop noise is obviously a factor, so part of the circuit board must also involve a ground plane design?
Reverse diode blocking spikes from starter, etc., possible source of failure, but doesn't the PMD fail much more often than other components like radio, sensors, instrument cluster (the only one I'm familiar with failing... emf spikes possible cause?)? Does this noise cause the amp to distort & give the pump bad control, deteriorating the pump also?
Regarding PCM replacement- reflashing/relearning the orgininal PCM would work just as well?
What switching power supplies? In the PMD itself? Is there a torroidal coil in there? If so, a coil big enough to handle 500 watts would be fairly large & also generate some heat...
Field effect transistors used instead; hmm... power supply again? What voltages are needed & being delivered, above the 12v already amply supplied by the alternator/batteries?
Logic circuitry regulated down... from where? Any logic chips on the PMD itself or all passive signals with possible noise? Is the harness shielded?
Lastly, knowing what you know- is there a component list for this thing? Is the reverse diode in a location that could be dremeled out & replaced, to confirm this fix as an option?
Tim Outland & I spoke on the phone today, & he said his remote mounted PMD (behind driver's side battery) has a thermal coupler that reads 109F when driving, 130F when idleing or shutdown. That's not much heat from a 500 watt device - seems like the heat sink would collect more heat from the engine rather than cool down the PMD. Mounting the device on the Pump meant counting on fuel to cool everything? Tim's fuel at 1/4 tank goes up to 160F, but this has got to be nothing compared to the 300F in the plenum, not to mention the engine valley radiation.
With your intimate knowledge of this device, did the transistors fail due to heat? Would noise filtering fix a bad PMD?
Seems like you know enough to design a better mouse trap?
Thanks,

[ 10-31-2003, 03:42 AM: Message edited by: StephenA ]

[vernj4]

ucdavis..........according to
http://www.fsdcooler.com/swe_web/index.html
they sell a fsd cooler for "Van/Hummer med 6.5 turbo diesel motor" for 1595 swedish dollars.

[StephenA]

I have emailed Christer Lindstrom, the guy in Sweden who is supposedly working on an upgraded PMD/FSD. I will post any response.

[gmctd]

Ah...I see the gauntlet has been thrown (and two weeks after the fact, at that), but - is offense truly the best defense?
Hmmmmmmm........my parry shall be, simply

di/dt = V/L

More?

V = Ldi/dt = L2 x I2/Toff

And again -

trr =1.41 x (Qr/ di/dt) 1/2

And, not even finally -

Irm (rec) = 1.41 x (QR x di/dt) 1/2

Now, factor in Entropy? Enthalpy? Empathy? Dam', what IS that word.........................

Gary, you still under that truck?

;)

jd

[ 10-31-2003, 02:20 PM: Message edited by: gmctd ]

[GARY PAGE]

Just got back from a business deal, been gone almost all week looking at yes power equipment. trip maybe tomorrow after a long nap, gone....

[S\W Off Road]

Originally posted by tom mac 95:
Gary- 1.)Sorry your rig's not running too well!
2.) The above post (10/29/03 11:37A.M.) by gmctd(member#1505, aka 'jd') is the second he's contributed in past year, indicating privileged familiarity with the FSD/PMD.
In a recent posting More Power indicated that the engineer responsible for the remote FSD Cooler has been attempting to devise a replacement driver assembly using mil-spec/aerospace components. This patient soul is known as:
Christer Lindstrom, BETA
Beta Maskin AB
Hogboleden 28
774 61 Avesta, Sweden
Phone no: 011 46 226 54070
Fax no: 011 46 226 50757
e-mail: mail@betamaskin.se
Perhaps you could communicate with these folks....
Many of us comprise an avid, willing audience for these efforts! I also am one of the many that has bought these over priced glorified black iodized heat sinks. It has not helped the first two FSD

[gmctd]

Ok - posts have been edited for content, and spelling, so I would like to continue this.

As I interpret it, Gary's concerns were that spurious parasitic oscillations, from the FSD\PMD printed circuitry, wiring harness, and\or the various solenoids involved, may be triggering the Driver between PCM signals. This could cause anything from thermal-break-down failures to secondary-breakdown failures in the drive or pre-drive transistors.

Either failure type can be intermittent - dies but restarts, to catastrophic - dead, no start.

He suggested installing a 'snubber' consisting of a Tantalum electrolytic capacitor for low frequencies, paralleled with a ceramic cap for high frequencies, to short these suspected oscillations to dc common/battery ground. Good engineering practice, it's right out of the textbooks.

The FSD\PMD OEM engineers did just that thing, internally.

There are several issues with that device, and I can offer some insight regarding them, and hopefully debunk some of the myth-information circulating around every so often.

Several articles by Jim Bigley, and Beta give primo information on the FSD\PMD and the remote-mounted FSD Cooler. If anyone wants to post links to that information, please do so.

I will start a new post - how does 'FSD\PMD - BFD' sound?

jd

[StephenA]

Yes JD, please start the new topic. Also, I'm interested in the threads you cited as background reading, do you know the topic headings?
p.s.
186,000 miles per second isn't just a good idea...
-it's the law.
:rolleyes:

[GARY PAGE]

JD just installed a new PSD this evening and truck made a 100 mile test run not a miss one and no stalls, so I think it

[StephenA]

Please read thread entitled:

FSD\PMD - BFD by gmctd (jd)

the curtain has been raised...

Perhaps this discussion is best continued there?
:cool:

[JohnC]

Originally posted by StephenA:
Please read thread entitled:

FSD/PMD - BFD by gmctd (jd) (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=005013)

[Bill H]

Here's some more food for thought that might inspire some clever dude to dig a little deeper into why these PMD's are so flaky. The PMD mounted on the IP failed, to the point that it would allow a cold start every time, but after idling for 5 minutes the engine would stall, every time. I unplugged the connector to the PMD and plugged it into another PMD (call it P1) mounted on a homemade cooler on the intake manifold. P1 cured the stalling problem, but it was a loaner from a friend, so I bought 2 more PMD's, one to run and one to carry as a spare, (call them P2 and P3).

I then made an extension cable to mount P2 behind the driver's side battery to keep it farther away from the engine heat. This worked fine for a few days, but one morning, no start. Switched back to P1 and still no start. Switched to P3 and VROOM !!! I couldn't believe P1 and P2 had failed, so I plugged them in again. Same story, P1 and P2 no start. Replaced P3 and VROOM !!! Still skeptical about P1 and P2 being bad, I removed the extension cable. Without the cable, all three worked fine! The point being that the connection/wiring to the PMD is so critical that if not just right, 2 good ones won't work while a third will work. How many good PMD's might have been replaced, when actually the connector or extension cable or wiring may have been at fault? Does anyone have a bad PMD they want to sell me so I can cut off the connector to make a better extension cable?

I also wonder how the PMD harness wires (16 or 18 gage?) can carry enough current to make the PMD get as hot as it does. Could one problem be that the wires aren't heavy enough? Could a little bit of extra resistance in the connector or wiring (from heat or corrosion or a slightly loose connection) cause the PMD to overheat?

[StephenA]

Bill H:
Your extremely well-managed experiments and results with PMD's & their placements & harnesses are exactly the kind of work it takes to nail this problem. If we put your data together with JD's actual hands on knowledge of the internal circuit & components,& contributions from others trying to tackle this this thing, we might just get somewhere.
Could I invite you (and everyone else) to continue this discussion on the new thread?

FSD\PMD - BFD by gmctd (jd)

This thread is meant to incorporate all the efforts from this thread as well as the one entitled VERY DISAPPOINTED WITH FSD DRIVER / COOLER.
If we consoldate all of our resources, I have no doubt that we could understand the full combination of factors involved & bring this expensive and frustrating problem out of the dark ages.
Thanks for the data!