Bosch 300 series washer motor control rectifier GBU 8j replacement

[highlander]

Hi everyone

Well I might need help and also might be also help some else who encounter this same problem.

Bosch washer Vision 300 or WFVC4400UC/29

symptom - no spin or agitate 

rest working find, it will fill water and drain water but during spin or agitate it just stay there doing nothing.

Belt ok, so performed the test program P:04 gives me error E:20 - communication or most likely motor control module. 

it cost near $400-500 CAD so owner just decided to replace by buying new one. but I am trying to see if I can fix it. 

removed the module control board, found the rectifier (4 pin) is fried. measured voltage drop diode mode

- with AC = voltage drop of 0.51  then reversed the multimeter leads Open (so ok)

+ with AC = voltage drop 0000 (shorted) then reversed the multimeter leads = voltage drop 0000 shorted ( so dead rectifier)

the rectifier showed GBU 8J looking online spec 

single phase bridge, 600V 8A (200A max surge current) 

but here in Vancouver, electronic store have in stock 

KBU 8K

single phase bridge, 800V 8A (300A max surge current)

does anyone know if that will work? are they made differently?

or I must use rectifier GBU 8J ?

would be nice to be able to fix this control module with a $4 CAD rectifier instead of $500 new motor control module 

thanks

for suggestions

 

[WOOKIE]

You can pull up the spec's for both at   ALLDATASHEET.COM  for comparison.  Any evidence of what caused it to short ?

[Vance R]

7 hours ago, highlander said:

does anyone know if that will work? are they made differently?

Yes and yes. It will just handle more amperage and higher voltage just cost slightly more to manufacture.

+1 for @WOOKIE question.

[highlander]

2 hours ago, WOOKIE said:

You can pull up the spec's for both at   ALLDATASHEET.COM  for comparison.  Any evidence of what caused it to short ?

I could not see any burnt or sign from any other place on the board, I was researching for any suggestions on repairs. I came up with YT video of a guy fixing another washer control module showing a 3 pin transistor. So I removed the heat sink and checked the rectifier, it was shorted. So hopefully that is the main problem

 

[highlander]

1 hour ago, Vance R said:

Yes and yes. It will just handle more amperage and higher voltage just cost slightly more to manufacture.

+1 for @WOOKIE question.

Great! Thanks

checking the spec, I thought should worked but just worry maybe it was made differently that can’t take the load. But you guys think should be ok right? Less than $4 I want to try it

just worry if might fry something else

[Vance R]

9 minutes ago, highlander said:

just worry maybe it was made differently that can’t take the load

Actually it is the other way around, the one you picked will take a heavier load. After you remove the bridge rectifier, ohm the board again to check for anything shorted. If all is ok then install the new one. Match the position of the symbols old to new when re-installing.

[highlander]

52 minutes ago, Vance R said:

Actually it is the other way around, the one you picked will take a heavier load. After you remove the bridge rectifier, ohm the board again to check for anything shorted. If all is ok then install the new one. Match the position of the symbols old to new when re-installing.

Thanks

yes after I removed the old rectifier, tested shorted + and ~, reversed the meter lead showed shorted too (diode mode)

- and ~ showed 0.55 voltage drop, reversed lead, showed open 

so rectifier is bad

[highlander]

Also with old rectifier off the board, measured board rectifier 4 pins location to ground, there are not shorted to ground.

so Monday will go pick up the KBU 8k and try it

will let you guy know the result. 
thanks
 

[highlander]

Hey guys,

received my new GBU 8J rectifier, installed the rectifier on the board but saw 2 thin circuit path on the board ( 1 mm thickness). Big path to big path but in between there is a thin 1 mm path burnt.  (both burnt path was from one of the big capacitor to the positive of the rectifier, so I soldered a thin wire on the board.

after installing the board back to the washer, still didn't work. I could see the drum trying to turn but like 1/8 of the turn. but still not working 

so put it on program mode. P:03 automatic full test.

I can heard the door click, water filling couple of times. then started to spin " ALIVE ". after finished all the test.

turn it off and switch it back to wash normal quick cycle and DA DA!!!!! working

spin and agitate!!! filled with water then switched it to spin and drain setting, working !!!!!! 

I fixed the motor control board!!!  NEW board was $400-500 - the rectifier cost me $30 CAD because of I ordered 2 just in case but 2 day UPS fast shipping was $20

2 rectifier was less than $10 

so remember after you fixed the board, still need to run for full test, I guess to remove the error codes.

then the washer will work 

love that I could fix it so this less than 10 years machine doesn't need to go to the JUNK!!! 

[Budget Appliance Repair]

GOOD JOB @highlander !!!!!!!

[highlander]

2 hours ago, Budget Appliance Repair said:

GOOD JOB @highlander !!!!!!!

Thanks

[Vance R]

 Good save.