Ulka vibe pump repair & fix

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
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Radio.YYZ

Postby Radio.YYZ » May 14, 2019, 9:16 pm

So looks like my vibe pump bit the bullet on my profitec pro 500. The machine is about 26months old so no warranty, i read and watched all the ulka videos to see what the main causes of failure are. My internals spring and ball and everything seems to be good.

My issue is the diode, on this ulka the diode is an external unit (I am assuming its the diode) and it seems to let current pass from both directions. The pump humms but there is no pumping action.

Anyone know where i can get this diode, if this is the diode or am i stuck buying a whole new pump?

Cheers

P.S. Repair on bottom of this post.


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( EDIT )

Repair for the pump when diode has failed internally.

Nunas wrote:Good discussion. I want to add for the non-techies, that this repair techniques does not always work. Diodes can fail open or shorted. If they fail open (you'll see no continuity with your ohmeter), adding a diode won't work. You need to see the same resistance (more or less) when measured in both directions on the coil (which is what the OP reported), which indicates that the diode has failed shorted and the resistance being seen is substantially just the coil. All this said, I would not bother. A failed diode is a failed link in a circuit. It isn't the equivalent of a wire of appropriate gauge for the current being drawn. For the small cost of these pumps I recommend simply replacing them.


ira wrote:If it's a diode, I believe any one of the series 1N5404 - 1N5408 should work just as well. Should be well under $1 if you find a reasonable source. Many of the choices at Mouser.com are $0.35 or less.

Ira


This is the diode that is implemented internally:

1N4007
=======
V rrm = 1000V
I favg = 1.0A
I fsm = 30.0A

T j = -55 to +175 C


As per ira's recommendation, i used the 1N5404:

1N5404
======
V rrm = 400V
V rms = 280V
I favg = 3.0A
I fsm = 200.0A

T j = -50 to +150 C


1N5408
======
V rrm = 1000V
V rms = 700V
I favg = 3.0A
I fsm = 200.0A

T j = -50 to +150 C



So i picked up some diodes @ 3A and 400V and tested it inline and the pump works! (Thanks to ira for the part numbers for the diodes)

So for anyone who has this issue its a pretty small cost repair but it will take your time if you are not used to soldering and doing electronic stuff. Took me about 15-20 mins to solder everything up.

I picked up a 5 pack and some 1/4" quick connect spade connectors so the diode stays away from the pump and wont fail from motion. I heat shrink'ed it with water proof heat shrink tubing with resin and left the diode open. Lets see how long this will last.

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( /EDIT )
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ira

Postby ira » May 14, 2019, 10:25 pm

If it's a diode, I believe any one of the series 1N5404 - 1N5408 should work just as well. Should be well under $1 if you find a reasonable source. Many of the choices at Mouser.com are $0.35 or less.

Ira

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Radio.YYZ

Postby Radio.YYZ » replying to ira » May 14, 2019, 11:02 pm

I guess i was wrong. It doesnt look like a diode and from the parts diagram its listed as:

C199900969 Thermostat Pumpe Heat sensor Pump
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ira

Postby ira » May 15, 2019, 12:27 am

Then if it's connected it's working and your problem is somewhere else. Have you tried taking it apart and cleaning it. I used to do that occasionally to my Gaggia and got it working each time.

Ira

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Radio.YYZ

Postby Radio.YYZ » replying to ira » May 15, 2019, 12:31 am

Yup took it apart, nothing was wrong and no debris.

I have the humm and no movement which from what i read is that its not oscillating for the pump to move and likely a diode failure in the coil part.

Basically a low hum when turned on and the pump action is not working, if anything specific i should look for i can take it apart as i have it out. The ball is there springs are in one piece and seals are in good condition.
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ira

Postby ira » May 15, 2019, 12:42 am

Measure the resistance of the coil both ways and if there is a diode it will show up, if not either find it or just add another one in line. If the diode is already there and good, adding another will either do nothing or make it very quiet, if the diode is missing, it should start working.

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Radio.YYZ

Postby Radio.YYZ » replying to ira » May 15, 2019, 12:49 am

Resistance only on the two terminal (bypassing the thermal sensor) is

191.9-192.0 Ohm
and
190.2-190.3 Ohm when reversed.

So if resistance is same means that diode is kaput? If so what kind of diode should i grab?
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ira

Postby ira » May 15, 2019, 1:19 am

Same diode I recommended in my first post in this thread.

Ira

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Radio.YYZ

Postby Radio.YYZ » replying to ira » May 15, 2019, 1:21 am

I guess polarity doesnt matter since its AC? and i can run it between the two spade connectors?
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ira

Postby ira » May 15, 2019, 1:42 am

It goes in-line with the pump, not across it.

Ira