Looking for MTH CV board AG-0000012

I have this one in my parts box.

Thanks, John....... sending you an email.....

Jesse

hi here is the chip on your constant voltage board in case you want to try n fix the old board!

Alan       https://www.digikey.com/produc...A34063AFS-ND/1054348

I have them also, but before you go chasing a chip, you just need to trace through to see if your getting power to the board.  Especially a good ground.  G

hi I AGREE GGG

Alan

Yes, getting power, and have good ground.  Classification lights function, headlight functions.  Cab and firebox not function, and headlight does not work with track power over 12V.  Also, look at pic I enclosed, have a fried resistor and possibly also diode.  Still have to test all out and see whether I can repair for a backup CV board.  Will replace with CV from John,  repace resistor and diode then test out.

GGG posted:

I have them also, but before you go chasing a chip, you just need to trace through to see if your getting power to the board.  Especially a good ground.  G

I agree 100% with George, I don't readily accept newer stuff for repair simply because I can't readily get the parts.  I actually typically know what to do to accomplish the repair, just don't have access to the parts and sometimes the info to make the job easy enough to justify doing it.

That resistor is probably 75 or 150 ohm for the markers.  If you have voltage out to HL, the same buss powers FB and Cab light at 6V.  So either a burned trace or bad bulbs.  The resistors are current limit for the markers also at 6V.

Measure the output voltage at the HL, if it goes above 6V maybe the reg chip is bad, or one of the components that help set the chip output to 6V.

Use Johns board to find the faulty component.  G

Thanks, George.  Yes, will be using the board from John to assist and check what outputs should be.  Notice the board I have in my BB is soldered connections, does not use the connectors, except the white one for the cab and firebox.  That is the white one located next to the coil.  Also, the location/output #J2, (other white connector) does not have anything soldered to it on the CV board in my BB.  I assume it is one of the earliest versions as I bought this BB in 1997... so it does have some years on it, and a lot of run time.

Thanks for your input, sir.... from all of you fine fellas.

Jesse

Broken solder joints under the connector for the pins???  There were many variations on this CV board depending on model.  Even a smoke output for the very first engines that had the seuthe smoke units.  Usually a silk print that tells what each jumper is, but it doesn't really matter.  All bulb outputs are 6V.  The marker is the one that has the resistors to limit current.  The smoke one is controlled via switch.  Otherwise pretty standard.  G

GGG...

On this BB, from 1997, the smoke unit is fan driven and wired directly off track pickup.  Yes, the bulbs are 6V and the markers are only lights to function correctly.  The cab and firebox are burned out from over voltage and the headlight only works at or below 12V.  All solder joints look good, only exceptions are the burned resistor and dark solder joints on the diode visible next to the chip.  Will make comparisons when I receive John's CV board and make repairs from there.  Have yet to perform second power out readings from board power feeds.

Thanks for the input, very appreciated.

Jesse

The board is on it's way, let me know how you make out.

Sounds like the burned component may have changed the setting of the Voltage out.  Good Luck and check for pinched light wires.  G

Thanks, John and George......

Yes, will inform of results with replacement board and when I check voltage outputs of old board.

Will inform when also finished with PS1/PS2 smoke units... and French drain around pergola, handrails around upper deck, more work on retaining walls of fish pond, spray staining of 375 ft front fence, etc.......     LOL!!

Jesse     TCA