TRANE VX90 Schematics Control Board

NormanSadler

I need schematic for a 59-4960 rev c Board. 

109A_5

Hello @NormanSadler,
You may have to buy Trane to get that. And they may not have it either since another company may manufacture the control board.
"Right to repair" I think it is not there yet. I think you do have the right to replace. Or right to just go without.

What problem are you having ? Did you inspect for poor or failed solder joints ?

NormanSadler

  Thankyou and I know that information can be proprietary.

 I have put an order in for a replacement board.

  I don't have enough information to solve the problem at the board level. It is not safe as well in my opinion.

  Although I am now the proud owner of two defective 59-4760 rev c boards.
  Both boards visually failed in the same manner. 0.022 cap leaked electrolyte all over the micoprocesser chip and a 0.47 cap below that leaked it's electrolyte on board components as well. 
  Both boards have some funcinallity. For example, when some input conditions are met, I get expected outputs. But some output responses I don't measure when Input conditions are met.
  Im building a bench test for the boards. Supply the 115vac, 24vac, connect correct loads, satisfying inputs and measurings outputs.
   I'm a Data Acquisition and Control test engineer and want to know what failed on the board.
 The boards are scrap now, but I want to see what discreet components, relay's, connections and or IC chips failed. 

         Thanks Norman Sadler

109A_5

Hello @NormanSadler,

NormanSadler said:

I don't have enough information to solve the problem at the board level.

Both boards visually failed in the same manner. 0.022 cap leaked electrolyte all over the micoprocesser chip and a 0.47 cap below that leaked it's electrolyte on board components as well.

Sound like you do have enough information. Clean off the corrosion, repair the circuit board, replace the failed capacitors and other components. If all the uP pins are intact it may work again. If traces are corroded away under the uP I would use the worst board as an example and remove the uP to see where the traces go and repair the other board with bodge wires.
0.022 Cap seems a bit small for an electrolytic Cap that would leak electrolyte.

I'm a Data Acquisition and Control test engineer and want to know what failed on the board.

Sounds like you do know, capacitors fail all the time, nothing uncommon about that. Their electrolyte leakage caused secondary damage, also very common.

With your 3rd (new) board, change the Caps before they damage the board, buy better Caps they are still inexpensive for the good ones.

Tim McElwain

Any alteration or repairs to boards on gas equipment is a liability and should not be done. Replace the board!