I bought a Railking Berkshire 30-1760-1 engine with PS3 knowing there was an issue with the electronics but I thought it might be an easy fix (drawbar, loose wire, etc).  Not the case though for it looks like a problem with the tender board.  I would like to attempt to replace a component (identified as U20) that I pointed out in the 1st 2 pictures.  This appears to be the only obvious problem.  I have had success in replacing PS2 smoke unit FETS so I feel fairly confident I can replace this.  Your generous assistance is requested in identifying the component and providing a Digikey link so I can purchase a replacement. 

I have tried both conventional and DCS but get nothing other than a garbled sound from the speaker and then it lasts a few seconds.  I have not been able to add the engine to my remote.  Any other suggestions from you or the other MTH experts would be most appreciated.

Thanks.

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Original Post

How do you know that component is a problem?  If you know enough to know it's a problem, I'd think you'd have to know the component ID.

FWIW, that component isn't even on the two PS/3 tender boards I looked at!

MTH PS3 Steam Tender Board

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It looks torched.  If it is, then it is more likely that it felt the brunt of something else being an issue, and wasnt necessarily "the" issue itself.  (In other words, if you replace it and the issue still exists, the new one will go up in smoke as well.) 

My boards are dead ones from my pile from repairs, those were the two dead tender boards I have, both look the same.  Yours is actually probably newer, from the product page.

Delivery Status: Delivered: JUL. 2018

Not familiar with that version of PS3.  Perhaps obvious, but best bet is to wait for more failures of this particular version to pop up on OGR.  Then, the functionality of U20 can be narrowed .  Then someone who has a functioning unit could identify the lettering/marking on the part which might get us to the part number.  Looks to be a 6-pin device and if I had to guess, probably a dual-power-FET which are $1 or so.

Good luck, my experience is once the PS3 boards are dead, they are fully and completely dead and no amount effort can resurrect them. They are up to 8 layered boards and there is most likely damage within the layers. Good luck with your repair but be prepared to pay the $160.00 for the new board.

stan2004 posted:

Not familiar with that version of PS3.  Perhaps obvious, but best bet is to wait for more failures of this particular version to pop up on OGR.  Then, the functionality of U20 can be narrowed .  Then someone who has a functioning unit could identify the lettering/marking on the part which might get us to the part number.  Looks to be a 6-pin device and if I had to guess, probably a dual-power-FET which are $1 or so.

Probably not captured well in the pictures but it is actually a 5-pin device (I'm assuming each metal leg is considered a pin).  I put as much light and magnification on it as I could without going cross-eyed and was able to make out what looks like "1 (damage) 9L".  Hoping this might help.

Matt Makens posted:

Good luck, my experience is once the PS3 boards are dead, they are fully and completely dead and no amount effort can resurrect them. They are up to 8 layered boards and there is most likely damage within the layers. Good luck with your repair but be prepared to pay the $160.00 for the new board.

I know it's a long shot but if the part can be identified and it is only $1 then I've got nothing to lose.

Thanks to both of you for your responses.

I think I answered my own question.  I have another PS3 Berkshire from 2015 but I thought the board would have changed over 4 years.  I finally took the tender shell off and sure enough it was the same board.  After putting some magnification on the board, I found the component was marked “189L”. 

Picture 7

A Google search returned this: 

https://www.ebay.com/itm/5PCS-...-189LS-/192831335506

A search of SC189LSKTRT returned these:

https://www.digikey.sg/product...C189ZSKCT-ND/2182343

https://www.mouser.com/Product...enoA2CYowj%2FQ%3D%3D

I will post after my repair attempt.

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Before you warm up the soldering iron, I just want to point out that part comes in output voltages varying from 1V to 3.3 volts, you might want to measure the output voltage on the good board so you know which one to buy!

SC189 SOT-753 base Parts

Here are all the voltages available with the same part family and footprint.

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I thought I would provide an update.  I received the part but while unsoldering the old part a couple of the contact pads came off the PCB so this made the already difficult job of soldering the new part to the board even more difficult.  I believe I was able to achieve electrical contact for all five points but unfortunately the engine still does not work.  It was worth a try though.

Next stop is the local hobby shop for troubleshooting.

 

You need to have the proper tools for working on SMT PCB work.  I use a hot air tool to remove small parts like that, I don't overheat the board and I get all the pins at once.  I've found I need about 550F (290C) on the hot air.  For larger parts, I clip the leads and remove the body, then sweep the leads off with the soldering iron set to 500F (260C).  Excessive heat is the kiss of death for PCB work, but too little will cause you to leave it on for too long and damage the board anyway.

Is the SC189L accessible when powered up?  

sc189

It's pretty much a sure thing that the SC189 purpose in life is generating the so-called 1.8V DC "core-voltage" to the processor chip (TMS320F28015).  Without its core voltage, the processor chip is dead.

From the SC189 datasheet you can see the VIN and VOUT pins on the regulator chip.  The circuit is most likely that shown in the "typical application circuit" albeit they show the 1.2V version.  It would take some close quarters probing but you'd only need a meter (as opposed to an oscilloscope), steady-hands, and good eyesight.  

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Apologies for the delay in responding....busy weekend!  

John, thanks for the good information.  Will keep this in mind for future work.

Stan, Yes, SC189L is accessable when powered up.  So the points to probe will be VIN & Ground and then VOUT & Ground?  

trainsbob posted:
... So the points to probe will be VIN & Ground and then VOUT & Ground?  

Correct.  I show the "typical schematic" because it's very tight quarters with the probing so could be easier to pick off VIN and/or VOUT by contacting one the capacitors or inductor.  It appears you can see the PCB printed-wires thru the green soldermask layer.

Hmm.  I see no silver lining in that cloud. 

Separately, it's my understanding that even the MTH techs at local hobby shops do NOT have schematics of the boards.  If this is true, I'm curious what kind of troubleshooting you/they think can be done? 

Determining if the board(s) are bad is done using the PS/3 test set, we can obviously do that.  You use a set of "golden" boards to test each board individually and determine if it's functional.  Here's my PS/3 test set.  It also tests HO and S-scale PS/3 boards.

How does it test PS-3 S Scale board?  Only if it is the O scale PS-3 board.  Actual S gauge board like 44 tonner has a connecter that the test set does not support. G

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George, I haven't pulled apart a 44-ton locomotive, so I wasn't aware that it had a different connector.  I know I got a ton of HO cables with this, and I (perhaps falsely) assumed that I should be able to test the S-scale stuff as well.

So, how do you test an S-Scale board?  Is that something they're going to support?

Not at this time.  Worked my first one a few weeks ago and realized no method.  SO I had MTH load SF for the board.  G

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Can one be a 'foamer' over test equipment? I would have no idea how to use it, but I get excited every time I see one of those MTH test rigs. It just has 'the looks'. 

I guess you can be a "foamer" over about anything.   I have trouble passing the tool dept in the big box stores, just as a reference.

It's not just test equipment and electronic gadgets, I too suffer from 'tool department' foaming. A tool department tour is a must on every trip to any store that has one!  

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