@derek-m 

IHi Derek,   will try a load resistor on the SIG/REF pins.

Given contradictory information from GRUNDFOS about the  Black and Brown PWM wires  is it  possible that the PCB output was damaged by being connected to the input PWM on the motor?

Why is the Return from the Motor going to a pin labelled REFERENCE ? What REFERENCE?

Would my connecting my scope earth to REFERENCE damage the REFERENCE /SIGNAL ?

The Grundfos specs give an amplitude of between 4 and 24 Volts, and , I used 12 Volts for my tests with the pulse generator.

ian

Posted by: @iantelescope

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@derek-m 

IHi Derek,   will try a load resistor on the SIG/REF pins.

Given contradictory information from GRUNDFOS about the  Black and Brown PWM wires  is it  possible that the PCB output was damaged by being connected to the input PWM on the motor?

Why is the Return from the Motor going to a pin labelled REFERENCE ? What REFERENCE?

Would my connecting my scope earth to REFERENCE damage the REFERENCE /SIGNAL ?

The Grundfos specs give an amplitude of between 4 and 24 Volts, and , I used 12 Volts for my tests with the pulse generator.

ian

 

Without knowing what components are on the Samsung PCB, it is difficult to say if it may have been damaged. Are there any cautionary notes in the documentation that stipulate care in connecting the wiring?

It would appear that power for the PWM input circuitry on the pump, is being supplied from the Samsung PCB, with pin 3 acting as a reference for both the input signal and the feedback signal on pin 2. The reference will be connected to some common point on the PCB, which may or may not be at 0v. The Grundfos document states that pin 3 is not connected to protective earth, but does not state where it is connected.

Applying a positive DC voltage to pin 3 could possibly cause a current flow through the 36v zenner diode to pin 2.

Connecting a scope that is earthed can sometimes cause problems.

The PWM SIGNAL output from a SAMSUNG PCB .........

To obtain this signal I changed the Field parameters 4051 for a Delta T of 3 C bringing up the "signal".

I then attached a 1k Resistor and the Signal died to a dc of 1.64 volts............

The SIGNAL is biased some 6 volts above zero and is running at exactly 1 khz.

The Output Power driver on the SAMSUNG PCB would appear to be faulty!

Any ideas.

ian

Posted by: @iantelescope

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The PWM SIGNAL output from a SAMSUNG PCB .........

To obtain this signal I changed the Field parameters 4051 for a Delta T of 3 C bringing up the "signal".

I then attached a 1k Resistor and the Signal died to a dc of 1.64 volts............

The SIGNAL is biased some 6 volts above zero and is running at exactly 1 khz.

The Output Power driver on the SAMSUNG PCB would appear to be faulty!

Any ideas.

 

ian

 

 

 

 

The fact that the voltage drops quite considerably may indicate a fault on the PCB.

Does the width of the pulse change if you change the DeltaT?

Do you have details of the conponents on the PCB? Do any look to have overheated?

@derek-m Cautionary notes from SAMSUNG ,GRUNDFOS

All of the notes from both GRUNDFOS and SAMSUNG cheerfully advise "that if it does'nt work reverse the wiring!

This is far from reassuring !

I will have to buy a new SAMSUNG Control PCB.board, or perhaps I could get an Arduino to control BOTH of my Motors .

The Primary water loop would be programmed to adjust the power using the PWM output from an Arduino.

Power = Flow_rate ( litres/sec) x Specific_heat ( KJ/Kg ) x Heat_pump_Delta_T( C)

with Delta_T = 3 C

flow_rate= 10 lpm = 10 /60 lps = 1/6 Litres per sec

Specific Heat =4.3 Kj/Kg X C )

Power operating point (Kw ) = 1/6 X 4.3 X 3 = 2.15 Kw

So, the system could be operated around a operating power of 2.15 Kw. with a 40 % PWM Signal.

With a signal of 10% PWM the power would be 3.2 kw while at 60% the power would be 0.95 Kw.

Most of the power control would still be that of the Variable Power from the Outdoor Heat pump itself.

ian  

@iantelescope

Assuming that the PCB is removable, you could try locating the faulty component and replacing.

@derek-m Delta_T and PWM control.

Hi Derek,

The "Signal apparent on my SIG/REF pair of pins on my SAMSUNG PCB changes slightly with the Dela_T setting on Field Parameter 2051 Delta_t.

The "Signal" is also unchanged with the control Factor control of 4051.

However, the Signal becomes saturated , i.e the Pulse width is greater  than the PWM Frequency resulting in the 12 volt DC with timing pulses ....

When changed to 70% the following happens

So the system is producing a control PWM only when using the 70% variable !

Nothing burning,overheating!

Faulty Output driver chip ?

Time for a new PCB ?

Time for an Arduino ?

ian

@derek-m 

I have got it !!I have TWO Grundfoss cables

One with the PWM output on the  Black wire

the second with the PWM on the the Brown wire.

NULL points to GRUNDFOSS!!

This is still a very odd signal ??

At this setting the Flow rate has set to 15.9 lpm.

Will experiment further!

ian

Posted by: @iantelescope

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Both pumps can be driven very successfully from a pulse generator set at 10 Khz frequency with a pulse width varying from 10 us to 90 us.

 

That would be outside the documented specs of the Grundfos by quite a margin.  I am surprised it worked.

@iantelescope

Where are you measuring the signal using the scope? What happens if you connect the cable to a pump? How does the waveform change if you vary the DeltaT?

@derek-m 

The Signal output from my Control PCB on SIG/REF appears to be faulty or incompatible with the motor load.

The Scope is connected to SIG with REF connected to the scope earth..

The "Signal" SIG drops to 1.6 V olts DC when the Pump is connected to the PWM input to the motor, the Brown wire.

A 1k resistor across the SIG/REF also kills the signal.

The Output impedance of the SIG/REF is far to high causing the motor to kill the signal.

The Output "signal" is also offset by 6.5 Volts DC .

I do not know but I  may have damaged the output chip in following the conflicting wire colour advice. Possible , but unlikely ....the circuit should easily withstand the wire reversal.!

With no displays of any kind, the unsuspecting User has no way of determining if the PWM system is working or not!

When the PWM does not work the user is presented with an apparently working system defaulting to the Maximum Flow rate..

I have decided to abandon the SAMSUNG PWM Signal and implement my own PWM Signal using an Arduino to control and balance the flow through , in my case, BOTH PWM Motors.

The Balancing , or positioning the flow rate into the centre of the control signal width  , as shown in the Piping Installation instructions on page 58 of the new installation instructions will be my starting point.

Something is amiss with the SAMSUNG Explanation as to why SAMSUNG alone, of the HEAT PUMP Manufacturers, does not automatically install PWM controlled pumps.

ian

Posted by: @iantelescope

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With no displays of any kind, the unsuspecting User has no way of determining if the PWM system is working or not!

disagree. pump behaviour tells User if PWM is working or not. 

Posted by: @iantelescope

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When the PWM does not work the user is presented with an apparently working system defaulting to the Maximum Flow rate..

agree

Posted by: @iantelescope

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I have decided to abandon the SAMSUNG PWM Signal and implement my own PWM Signal using an Arduino to control and balance the flow through , in my case, BOTH PWM Motors.

ok, good luck!

Posted by: @iantelescope

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Something is amiss with the SAMSUNG Explanation as to why SAMSUNG alone, of the HEAT PUMP Manufacturers, does not automatically install PWM controlled pumps.

 

disagree. documentation from at least one samsung supplier shows how to do this and its clearly documented in Samsung manuals. I said this before already.

The fact yours doesn't have it is a different issue.

one more thing, I don't understand why you won't just go through warranty with samsung. It does seem that you have evidence that your PCB's PWM output is bust. But that's up to you.