Brueheinheit blockiert MIELE CVA 620

Diskutiere Brueheinheit blockiert MIELE CVA 620 im English Section Forum im Bereich *** Allgemein***; (I hope English is not a problem) Helle, I've got a MIELE CVA 620 cofee machine which to me is like the Saeco Royal Magic. The brewer unit was...
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  • Brueheinheit blockiert MIELE CVA 620 Beitrag #1
I
ikheetookAxel07
Teetrinker
Dabei seit
09.07.2011
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Hoek van Holland
Vollautomat
MIELE CVA 620
(I hope English is not a problem)
Helle, I've got a MIELE CVA 620 cofee machine which to me is like the Saeco Royal Magic. The brewer unit was blocked. After trying again, smoke came out of the electronics. A capacitor (Drossel) was burned. I replaced it and machine seemed to work again.
When making a cup of coffee, the program ends with message 'VERW GROEP GEBL' which is Dutch for "Brueheinheit blockiert!. Befor this message I got the message "ONTLUCHTEN"(Entluften)Also when starting up the machine the flushing programm end with 'Blocked Brewer". As I manually operated the microswitches without the brewer unit installed, it can not be a mechanical problem.
What I found out is that the water pump is not working in the program. When I operate the pump manuallly (Taking hot water) than it works OK. So my conclusion is that output components between Microprocessor and pump fail.
I have run the Test programm. All signals of microswitches are OK. Also the brewer motor runs OK.
But when pressing the Watercup button (left bottom), the diplay show '5'but nothing happens. Also the lamp between the the two lower bottons lits up when pressing left bottom button. It looks like this is the test button of the Pump which is not working.

Does somebody have a clue what could be wrong with the electronics (or is it something else).
Thanks for your cooperation,

Jelle
 
  • Brueheinheit blockiert MIELE CVA 620 Beitrag #2
hmilbradt
hmilbradt
Super-Mod
Dabei seit
03.01.2005
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27.150
Hi,

The pump uses a half-wave rectified voltage. The diode is embedded in the pump.
In order to test the pump it may be connected to mains.
The picture shows the pump circuit on the board .... kein-dampf-pume-taktet-pumpe

The error message "brew unit blocked" is a separarte problem ....
Removal of a blocked unit ....

  1. blockierte Saeco-Brühgruppe ausbauen
    ---- Autor: Michael Landmann

  2. Saeco Brew Goup Removal
    ---- Saeco-USA -- Cerini Coffee - USA

Trouble shooting the brew unit power circuit ....

  1. Stromkreis messen
    ---- Posting von hmilbradt


regards
Harry
 
  • Brueheinheit blockiert MIELE CVA 620 Beitrag #3
I
ikheetookAxel07
Teetrinker
Dabei seit
09.07.2011
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4
Ort
Hoek van Holland
Vollautomat
MIELE CVA 620
Hi Harry,

Thanks for the quick answer.
  1. I've already tested the pump, I builkt in a new pump because it was not priming anymore. So this is not the case.
  2. The Brew group is not blocked. I did the testing without the brew group.
  3. I measured the resistance of Motor windings: 19.6 Ohm. Voltage when running is approx 16 V.
    Time of brewer to go upwards is about 9 sec's
What still wonders me, is that I can control the pump manually, but doesn't switch in the coffee make procedure!
Do You think the triac has blown?

Tnx in advance
 
  • Brueheinheit blockiert MIELE CVA 620 Beitrag #4
hmilbradt
hmilbradt
Super-Mod
Dabei seit
03.01.2005
Beiträge
27.150
Hi,

The pump is switched on by the brew unit microswitch, when it reaches the exact end position. Since you got a low voltage in the circuit, it's possisible that this position will never be reached.
The low voltage is the result of a malfunctioning NPN-power transistor (attached to the cooler !!) and/or the zener diode in the voltage divider R=100 Ohm and a zener ZD=33V / 1,3 W that creates the base voltage of the NPN-power transistor.
Replace both NPN-transistor BD 245C/TIP 33C and the zener diode.

regards
Harry
 
  • Brueheinheit blockiert MIELE CVA 620 Beitrag #5
I
ikheetookAxel07
Teetrinker
Dabei seit
09.07.2011
Beiträge
4
Ort
Hoek van Holland
Vollautomat
MIELE CVA 620
Hi Harry, I think this makes sense. I wil replace components and let you know!

Tnx
 
  • Brueheinheit blockiert MIELE CVA 620 Beitrag #6
I
ikheetookAxel07
Teetrinker
Dabei seit
09.07.2011
Beiträge
4
Ort
Hoek van Holland
Vollautomat
MIELE CVA 620
Hi Harry,

I replaced the Power transistor first. After that I also replaced the zener diode. The last solved the problem. The zener seems to increase the voltage a bit. Now the brewer movers in position within 4 sec. (9 sec. before). I think the time is measured by the microprocessor which gives failure of blocked brewer.

Thanks very much for your help.

Jelle
 
  • Brueheinheit blockiert MIELE CVA 620 Beitrag #7
hmilbradt
hmilbradt
Super-Mod
Dabei seit
03.01.2005
Beiträge
27.150
Hi,

The replacement should be done the other way around .... first zener and then power transistor. The zener controls the transistor ... a long test with a faulty zener could already create partial damage to the new transistor.
The operating range of a 33V zener lies between 31 and 35 V.

regards
Harry
 
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Brueheinheit blockiert MIELE CVA 620

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