TIU VARIABLE CHANNEL NOT WORKING

Hi folks

 

 My TIU  variable channel #2 is not working . It seems that is due to a damaged output FET. So, it was only possible to see the code of the first TR, which is IRFZ44N. My question is: are all 4 TR's of the same type?

Thanks for reply in advance

A.C.Sant Anna

Original Post

What rev is your TIU?

 

 

TCA-79-13758

T.T.O.S.-3057

LCCA-28444

LOTS-RM-4833

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Member Mid America 3 Railers and NJ HiRailers

 

 

 

Rather than start a new post I'd thought I'd add to this one. I have a simple two track setup power from the Z-4000. I haven't used the track much over the past year. This weekend the z-4000 won't go over 3.3 volts on one channel - both outputs are the variable voltage 1 and 2 outputs. One channel will increase to 15 volts or so and power the locomotives but if I increase the power going to output2 both left and right channels will cycle down until it shuts off. I have checked the track and connections and can't see what the problem is?     

Confusing, is this through a TIU or z-4000 alone?  If the Z-4000 has an issue powering track by itself you have a defective channel on the Z-4000 that needs to be repaired.  If the Z-4000 works fine by itself, the TIU has a shorted channel most likely.  Are you getting an overload signal on the Z-4000?  G

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Sorry, the connections are on the fixed voltage channels. The z-4000 works fine when not connected to the TIU and there is no overload signal when not connected to the TIU. The TIU was replaced last year so baffled why it would fail now as I have hardly used it. Is there anything that can be checked or a fuse replaced on the TIU or is it shot? When connected to the TIU the fixed voltage 2 won't go past 3.3Volts and cycles both outputs down to zero

If the TIU channel is shorting, the top suspect on fixed channels is the TVS protection diode.  They're a large thru-hole component and fairly easy to replace.  It's not uncommon for those to fail shorted.

Here's a picture of the TVS diode locations in the Rev. G, they're in similar locations on the later versions, but I don't have one apart to check.   Pretty easy to spot, they're large cylindrical components.

Well, to start you can just use an ohmmeter to check across them, a shorted one will read either zero or a very low resistance.  If you check all four, and the problem channel is markedly different, I'd simply replace the TVS.  As a simple test before you have the part in hand, you can just remove the problem one.  The TIU will operate fine, it just won't have the transient protection afforded by the TVS.

I was running the train on the one good track left just to demo it to some visitors but then that one remaining track stopped working. It says engines not found even tho they were working fine just prior. can't get them back to working. The one track indicates good power 21volts I think and the amperage is good. However, engine will only start up if I directly power from the transformer to the track. I'm taking apart the TIU tonite but it seems as maybe another issue has developed?  Where can the diodes be purchased? I think all the goold ole Radioshacks have closed around here     

I finally got to the TIU - are these soldered in place? As soon as I can find my ohm meter I'll check them out. I have a DCS Commander so I hooked that up, the locomotive is found and starts up, however it won't run. I just have it from Dc Track power output to my track and put in DCS command mode but the loco won't move. I did try a couple of different locomotives and switching the cable around. So I'm wondering if it is in fact the TIU or something else?  If I hook the track directly to the z-4000 it will run locomotives fine. I did search the site last night for some help but couldn't find this particular problem and the DCS manual is pretty limited.

gunrunnerjohn posted:

Yes, they're soldered into the board.  If the TVS is shorted, that channel will be dead on the tiu.

If shorted it won't be dead, it will short the transformer. G

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GGG posted:
gunrunnerjohn posted:

Yes, they're soldered into the board.  If the TVS is shorted, that channel will be dead on the tiu.

If shorted it won't be dead, it will short the transformer. G

Sound dead to me, that's what I meant.

gunrunnerjohn posted:

If the TIU channel is shorting, the top suspect on fixed channels is the TVS protection diode.  They're a large thru-hole component and fairly easy to replace.  It's not uncommon for those to fail shorted.

Here's a picture of the TVS diode locations in the Rev. G, they're in similar locations on the later versions, but I don't have one apart to check.   Pretty easy to spot, they're large cylindrical components.

With the talk about loose connections plugs in another post, would the 6th nut on the bottom be considered loose?  To me it looks like the nut is not tight.  I have not opened mine up, it has been put away for probably 7+ years, but will be coming out this fall as I am almost done with all my track.  Want to make sure what I need to look for.

Thanks

Probably, that was an old Rev. G TIU that I was working on when I annotated it with the TVS positions.  However, you'll notice that the wires are soldered onto the ends, not just secured with nuts like the later versions.  The clue is there are no fuses, all the later versions have the 20A fuses. 

The only downside of a loose jack in a Rev. G is... a loose jack.  It wouldn't affect the actual connection in this version.

I followed the link to order the TVS - I received and they don't look the same, looks a tad bigger. Also when checking with my meter I didn't get any readings on the new ones? I installed anyway due to desperation and the TIU seems to work, the transformer powers up and I can increase the voltage as before. Still can't see any locos, add or do anything. I can only run one loco by hitting the reverse button and cycling the power. On the second track I can't even start up a loco. Both tracks are fixed voltage tracks and fixed out but it says out of range briefly and then finds nothing to add. 

So I decided to upgrade the software to version 6, the TIU upgrade went smoothly but I can't get it to upgrade the handheld. I have a serial adapter and a USB cable - with serial adapter I get a message saying my computer doesn't have a serial port (even using the adapter cable) and with the direct printer USB connection it search's for TIU on Com 5 I get a message saying TIU is having a hard time finding USB connection and to cycle power - which I have tried a number of times. I've done a software upgrade before but no luck this time.

You will get no readings with a meter on a good TVS diode, they will appear to be open in both directions.  The exact size of the package is not significant as long as it has the right ratings.

What computer O/S do you run?  For Rev. L TIU's, I just fire them up and run with them for Windows 10.  What you describe sounds like an issue with the USB drivers.

Did you open Device Manager and check to see if your adapter cable is recognized?  I have a serial port card, so ignore COM4 and COM5.  I plugged my Vantec USB To Serial Adapter (CB-USB20SR) adapter in and it shows up as COM11.  I use this with my laptop for older TIU's and for the Legacy command base communications.

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On my computer running windows 10, the serial device had an asterix next to it and I couldn't update the driver - I reinstalled the app on another computer and was able to update the handheld after a few attempts using com 3 this time. Hopefully now I can run some locos!

Sometimes on Windows you have to display hidden devices and then whack all the drivers in the section and let Windows reload them.  An inactive driver can frequently screw up the works.

I installed everything back ans the wifi module purple light flashes. Don't know if that's normal. I have two engines on one track and a single engine in another separate loop. All engines fire up and idle in protosound mode. However using the handheld and the wifi app I can't add engines. It simply times out on the app and handheld says no engine to add. Any advice? Also trying to figure if the tiu is workinkonf correctly so don't know if blinking purple light is correct. After the software upgraded all locos immediately start up which is a step forward. 

Are you absolutely certain that you haven't inadvertently revised the wires between the TIU channel output and the tracks?

Is the TIU being powered either via Fixed #1 Input or the Aux. Power port while you're attempting to use the variable channels?

Barry

 

DCS Ambassador & author of The DCS Companion series of books

Train-Ca-Teers - All For O and O For All!

 

I am not using variable channels, input is fixed 1 and fixed 2 with corresponding output jacks. I have each feed going to a terminal block one for each track. I'll double check tonite the wiring. I am thinking with the TVS problem with the TIU something has messed up the TIU which is why the purple light is flashing on the wifi unit? I have also used a brick in conjunction with the 4000 to power the tiu aux power port but it makes no difference. Should I be using variable channels?     

Should I be using variable channels?     

Not unless you have a legitimate reason to do so. For command operation, Fixed channels should be the first choice.

Barry

 

DCS Ambassador & author of The DCS Companion series of books

Train-Ca-Teers - All For O and O For All!

 

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