saeco vienna deluxe (temp light middle lights up right away)

[stanman]

hello,

problem with saeco vienna machine. changed temp sensor and middle light
does not flash to show boiler heating up, but goes on solid right away.
checked resistance of temp sensor at startup = 1.92 k.
in test mode boiler heats up. when i start machine it goes from 1.92k to infinite resistance. everything else checks out ok . could be problem with control board
(m5svvv1-1)

thank you for reply,
Peter.

 

[schluerf]

Hello,
make sure that the sensor connections are clean and you also have to check the board for short circuits caused by steam and coffee powder.
Temp sensor resistance (KTY10-6):
20°C/68°F=1.926k
50°C/122°F=2.390k
95°C/203°F=3.179k
Check teperature:
Go to test mode (coffee switch+ steam switch+ power on)
press coffee switch+ steam switch again and read tempcode:
Temp LED
<95°C/203°F alarm
95°C/203°F coffee+ alarm
96°C/204.8°F coffee
97°C/206.6°F coffee+ steam
>97°C/206.6°F steam
With connected reference-resistor (3.246k=96°C/204.8°F) instead of temp sensor, the displayed temp should be 95°C/203°F to 97°C/206.6°F.

 

[stanman]

thank you i will check.

 

[stanman]

in test mode temperature shows up as >97c. but boiler cold.
when i energize boiler in test mode it heats up.
i checked board for shorts and everything seems ok.
when i power board on connector goes from 1.92k to -4.41 on display. when i switch multimeter leads goes to infinite.
what part on board can be checked if problem is that ?

thank you for reply
Peter

 

[stanman]

is there a way to make a change to board to start boiler manually so it stops at right temperature by using temp sensor and bypassing microprocessor?
thank you.

 

[ksb]

Hello,

check the resistor, capacitor and transistor of the temperature measurement circuit

see: Leistungs- / Steuerplatine - M5SVV1-1 ----------- Autor: WolleP

Regards ksb

 

[stanman]

Thank you very much i will check and report back to you.

Peter.

 

[stanman]

I checked all components of temp circuit everything ok and still same problem . Im really stuck.
could it be a microcontroller problem ? what else can i check?

Thanks
Peter

 

[Jürgen aretz]

I had a similar problem with one of my Viennas. The red LED was permanently ON after switching on the machine. No other functions was possible. After a while, steam came out of the unit and shortly thereafter, caused by the water steam, a short circuit on the control board happend. Thereafter, the board was no longer usable. The error was caused by a completely calcified heating, the water no longer ran, so that the machine could not be vented. Not even the Wassepumpe was running. With the lime and the high temperature in the heating, the pressure was so high that the housing of the heating burst, whereby the water entering the machine, causing the short circuit on the control board.
So my tip, if other parameters are correct, I would open the heating and descale. With the normal Descaler nothing could be done.
Good luck
Jürgen