K5AV1-2 / Board fixed

tsehested · 11.03.2008

Hi all

Does anyone have a part list for the K5AV1-2, need the values of R4 & R5

Have repaired this board many times due to steam damage. Would like saeco to release the schematics soon ?(

via babelfish

Tut jedermann haben eine Stückliste für das K5AV1-2, benötigen die Werte von R4 u. von R5

Haben dieses Brett viele Male wegen der Dampfbeschädigung repariert. Möchte, daß saeco die Diagramme bald freigibt

Thanks,

Thomas

ksb · 11.03.2008

Hi tsehested,

saeco will never release any circuit diagrams......please tell us the position of "R4" and "R5" on your board or show us a good picture....

Best regards

KSB

tsehested · 12.03.2008

Hi KSB

I did find the R4 on some other pictures of the K5AV1-2 board. 4,7K, but could't not make out the R5.

Anhang anzeigen 2858

Thanks,

Thomas

ksb · 12.03.2008

Hi tsehested,

sorry - i have no picture of your board - try to examine to which component "R5" is connected - if it is a green LED, a 470 Ohm resistor would work. For the red LED 270 Ohm is suitable.

Best regards

KSB

tsehested · 13.03.2008

Thanks KSB

Did lead to the red LED, but still not working!

I get the power LED + the steam LED when powered up...and a brumming brew motor X(

The middle gren led was burned + R4/R5. Have replaced the TIP33C /ZD, will try to get RV5 / RV6 tomorrow.

Is there a test decription with the board out of the machine...

Thanks,

Thomas

ksb · 13.03.2008

Hi Thomas,

which is the amount of the supply voltage between the middle to the right pin of the voltage regulator ?

The target value ist 5V - which is the value of the resistance between the mittle and right pin of regulator ?

We have a german description - if your machine will show some reaction i try to translate it for you.

Best regards

KSB

tsehested · 13.03.2008

Hi KSB,

The voltage is 4.99, so fine...the R value (pin2/3) is 91.9 ohm. I always check the 78xx & 79xx in any electronics....

Just replaced the red LED + T12 (bc557). So the initial burn was the middle green LED + the red LED and then T12 / R4 / R5

Still a brumming motor, but a delay in motor start after replacement of T12, so hoping the cpu is still OK

Think the whole thing started with the brew mechanism being to heavy to run...the machine was very slow and squirky :wacko:

Thanks,

Thomas

ksb · 13.03.2008

Hi Thomas,

91 Ohms at pin 2 and 3 of the voltage regulator is too much - the nominal value is about 25 Ohms - check the voltage between pin 14 and 28 of the controller - the target is 5V too. After this check is positive, it is quiete sure that the controller is damaged. In Germany there is a cheap spare part available. The other solution is a cheap used but tested spare board from www.dicofema.de

If you detected an other and the resistance is normal again fault try to enter the test mode:

1. Power OFF
2. Press the "Steam" and "Coffee" button together and
3. switch on the machine.

Best regards

KSB

tsehested · 13.03.2008

Hi KSB,

4.99VDC on 7805, but only 2.5VDC between pin 14 / 28

This test is with the board out of the machine, and mains on jp10 / jp11

Thanks,

Thomas

ksb · 13.03.2008

Hi thomas,

so there is still hope for the controller - try to find the reason for the voltage drop in the supply - maybe a copper trace of the pcb is damaged...

KSB

hmilbradt · 13.03.2008

4.99VDC on 7805, but only 2.5VDC between pin 14 / 28

Hi,
Please confirm these voltages. If the voltage regulator 7805 outputs a stable 4.99 VDC, the voltage between pin 14 and 28 should show about 4.99 VDC too. On a Vienna M5SVV1-1 board the line resistance from pin2 of the 7805 to pin 14 of the microprocessor is only 0.6 Ohm. The same applies to the +5VDC line to pin28 of the microprocessor. If there is a short betwenn theses parts, it is supposed to feedback.

regards
Harry

tsehested · 14.03.2008

Hi,

There is a nice 4.99 VDC on pin 14 / 28. One have to measure on the right pin's

can only be explained by bad coffee

Still a 91,9 ohm one pin2 / pin3 on the 7805 :|

Thanks,

Thomas

hmilbradt · 14.03.2008

Hi,

The 91.9 Ohm load amounts to a 55 mA current drawn from the power supply ---- according to Ohm's law. This is probably a normal condition. A 2-VA Transformer is able to deliver about 222 mA. But there is a slight loss created by the 7805 regulator. The current limit is reached if the board-load decreases to about 25 to 30 Ohms.
Your problem is a humming brew unit motor. Look for the power connector of the motor. It has the cable colors yellow / yellow / red / blue.
Yellow / yellow is conneted to a heating element on the boiler. It is used as a dedicated resistor and is supposed to decrease the voltage for the 33 VDC motor which is connected by the red / blue cables.
1. --- measure the voltage drop between both yellow cables --- the target voltage drop is about 80 to 85 VDC
2. --- measure the voltage of the motor coil ( red / blue) using the test mode of your machine.
3. --- measue the resistance --- target values 130 Ohms (drop down resistor) and 25 Ohms (motor coil)
The voltages are supposed to be DC, but check AC as well for a Triac break down. The Triac acts as a half-wave rectifier.
This attachment contains additional infos. It shows the standard Saeco solution of the brew unit motor voltage regulation.

regards
Harry

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tsehested · 14.03.2008

Hi Harry,

The voltage between the 2 yellow is 180 vac. 128 ohm on the element.

Motor gets 28 volt. ac aswell, no dc on either of them.

Test menu does nothing...

Thanks,

Thomas

hmilbradt · 14.03.2008

Hi,

Search the triac that is connected with the pin of the blue cable ( middle pin = anode2 of the triac). On most boards it's a T410-700T. Test this triac and it's associated variable resistor S07K275 ??). Probably one of them has developed a short. If my assumption proves true, change both items.

regards
Harry

tsehested · 14.03.2008

Hi Harry

Have now replaced all varistors, could't not find a shorten one though...

Can't get the T410 700T down here...got another triac...BTA08 600B ...8A 600v, haven't checked if it can be used yet....

Have all the T410 out of the board. The T8 is a little bit different compared to T5 /T7

T8 A1/Gate 403 ohm, Diode test 0,228

T5/T7 A1/Gate 323 ohm, Diode test 0,187

A2/Gate or A1/A2 25 Mohm on all of them. So almost infinite

Thanks,

Thomas

hmilbradt · 14.03.2008

Have now replaced all varistors, could't not find a shorten one though..

Hi,
Why did you replace all varistors ? That's overkill. By the way it is almost impossible to find a weak varistor with a digital Voltmeter. Most DVMs operate with a 9V=battery. You may measure an indefinite resistance of the varistor at the 9 V level. The short could occur at a higher voltage level but well below the level required by the circuit.
The main point is to find the triac, which serves the pin of the blue cable. This triac has probably developed the short (I'm almost sure).
The best way is: Touch with one DVM-probe the (blue) pin of the motor socket and with the other probe the cooling fans of all the triacs in the vicinity. If you hear the sound of the DVM, you have found the proper one. Test this triac with the Rockwell procedures descibed in this link ---> Ersatztypen für Saeco-Halbleiter The table shows replacement triacs of the T410-700T (TO-220 package). In the foto I have found (board K5AV1-2 - Krups Palatino) it seems to be T8 / RV5--- see attachment.

regards
Harry

tsehested · 14.03.2008

Hi Harry,

Well for 33 cents/euro for all 7, why not...need a cup of decent coffee soon....machine has been broken for a while now.

Touch with one DVM-probe the (blue) pin of the motor socket and with the other probe the cooling fans of all the triacs in the vicinity. If you hear the sound of the DVM, you have found the proper one.

??? in what mode....never heard my fluke make a noice unless in Diode test mode! Or on the fabric in a crt/tv :S HMm

If we say that my T8 was bad...can I lend either the T5 / T7 to test....well know my water pump runs fine...so did the mill. And yes it is a Krups. But not much on the net about Krups. And I had a Saeco for repair long time ago(ball was stuck)...figured it was the same machine. But think mine is very early version.

Looked up the BTA08 600B, the only difference is that it's 8A, and the sensitivity is 50 mA where the T410 is 10 mA, so don't know if this triac is sensitive enough? It's insulated on the cooler plate...

Thanks,

Thomas

hmilbradt · 14.03.2008

Hi,

My DVM uses the max. 200 Ohm range. If the measured resistance is below 200 Ohms -- a beeper sounds in addition to the value displayed. If no beeper is integrated in your DVM, use the lowest range and watch the display. You have a direct connection, if a low value >> 1 Ohm ist displayed.
Most triacs on the boards are not isolated, that means the anode 2 (middle pin) is connected with the cooling flag.
Be carefull: While working with a hot board, never touch the cooling flags. Maybe their potential is 230 VAC.

By the way -- early boards used hardware half-wave retifiers (type - 1N540x) with extra triacs to switch it on/off for the proper rotation. But a couldn't find those on the foto I have. Later versions use software controlled halve-wave rectification via a triac.

You mentioned the grinder is working o.k. This further confirms my assumption that T8 ist the bad guy.

regards
Harry

tsehested · 14.03.2008

Hi Harry,

Hmm should I try to use T7, that's the one for the water pump. Don't think I would do any harm by testing without the T7 in?

What do you think about the BTA08-600B, same pin configuration, but different sensivity...

Thanks,

Thomas