Troubleshooting Chance PI

[Borisimo]

Having constructed the Chance PI board, I am in the troubleshooting stage (i.e. it doesn't work).

During the build I replaced the Q2 KP505 with a 2SC945, but having referred to the data sheet have placed it in reverse to comply with notation (E, C, B on the circuit board).

The question then arises should Q1 also be reversed?

Also, the general behaviour of the board when started is that the LCD flashes a row of black bars and then goes dead, but I can hear a soft ticking through the speaker. This occurs at a rate of about 34 a minute.

I am using 12v (8x1.5v), and a home made coil (based on Baum7154 excellent work) with 480uH.

I cannot change any settings at this stage.


So the questions are;

- Should Q1 or Q2 be re-orientated,
- Are there any obvious issues on the board
- Is there a general approach to trouble shooting on Chance

Photos attached.

Any advice most appreciated.

Boris



PS Also I have found a general 'troubleshooting' website (which I have not read yet) which may be useful for other readers. http://www.angelfire.com/planet/funw..._Contents.html

[baum7154]

Boris,

I am at work now but please verify that the emitter of Q1 is going to the junction of D1 & R1, the base to the junction of D1 & R2 and the collector to the junction of L1,C1 & C6. Then verify that the emitter of Q2 is going to ground, the base to the 3.3K resistor, and the collector is going to the junction of D1 & R2.

I'll check your results later today.

Good luck!

Dan

[Borisimo]

Dan,

Thanks for you rapid reply, I am a beginner so apologies if I miss something.

I have done visual tracing rather than anything more complex such as a signal tracing method.

Results.

Q1
Emitter -> Q2 (Collector), R2, D1
Base -> D1, R1
Collector -> C1, L1, Q3 (IRF9640), R2

Q2
Emitter -> Not sure, it appears to connect to the 'wide border' which would connect to the corner holes so I think this is ground.
Base -> R3 (Although the reading here is strange, both of my DMMs flash a value and the go open circuit, i.e. value of 1.)
Collector -> Q1 (emitter), R2, D1

Boris

[Borisimo]

I forgot to mention that I am using the attached datasheet as reference for the C945P transistor.C945P-NXP transistor datasheet.pdf

[silverdog]

Q2 Kp505 cannot be replaced with 2SC945
see attached diagram for replacements - always check orientation

[baum7154]

Silverdog,
In the latest board revision of several years ago, compatible with the version 1.2.1 firmware, the KP505 was replaced with a 2SC945 but other changes were made to accommodate this revision per Fandy's web site. I thought your present boards have these revisions in them as follows:

Changes to the original board configuration:

R9 - 820 ohm

D1 - across R25

3.3K from base of Q2 to 'TO' of the Uc

D9 - deleted

1N4148 across SP1 & SP2 Cathode at SP2




Boris, did you get your circuit board from Silverdog along with a pre-programmed Atmega microcontroller? If not, did you make your own board or get it elsewhere. If so, what version is it?

Regards,


Dan

[Borisimo]

Dan,

Yes, I got the board and the Atmega controller from Silverdog in February 2016, I assume it is version 1.2.1.

While I was sourcing the other parts I found this comment in a mail at https://www.felezjoo.com/viewtopic.p...=671&start=140 ...'Please insure that you are using the latest modifications to the Chance as the KP505 was replaced with a 2SC945 transistor. This was necessary in order for the unit to operate properly with the version 1.2.1 software'.

Cheers,

Boris

[silverdog]

If you have the 1.2.1 version the pcb is amended to reflect the Q2 now being a 2sc945 , so it should be inserted as per the silkscreen for both Q1 and Q2
Does the LCD contrast trimmer have any effect ?
What voltages do you have on 7660 pins 5,8 ?

[Borisimo]

Thanks Silverdog,

I think I see one of my errors. I have read the datasheet image as a plan view, rather than the view of the underside of the transistor with the legs pointing towards the viewer.

I will change this and give you an update.

How do I know which version I have? The board has 'CHANCE v1' on it, but I don't know how to read the firmware version.

Does the LCD contrast trimmer have any effect ? Yes, it gets darker as I adjust the trimmer.

Thanks for your advice.

Boris

[Borisimo]

So...last test before bed.

Transistor Q2, replaced in position as per the silkscreen, and Q1 as per silk screen. Slight change, but still black bars and soft ticking in the speakers.

Resistor R3 re-tested and value around 22k

Voltage at U1 (7660) Pin 5= 11.2V, pin 8 -11.2V

Boris

[6666]

Silverdog,
In the latest board revision of several years ago, compatible with the version 1.2.1 firmware, the KP505 was replaced with a 2SC945 but other changes were made to accommodate this revision per Fandy's web site. I thought your present boards have these revisions in them as follows:

Changes to the original board configuration:

R9 - 820 ohm

D1 - across R25

3.3K from base of Q2 to 'TO' of the Uc

D9 - deleted

1N4148 across SP1 & SP2 Cathode at SP2




Boris, did you get your circuit board from Silverdog along with a pre-programmed Atmega microcontroller? If not, did you make your own board or get it elsewhere. If so, what version is it?

Regards,


Dan

The v1 pcb does reflect the mods, but the diode across R25 is now called D9, the diode across SP1 and SP2 is D10.

[Borisimo]

Video of the problem available at https://youtu.be/bNMcsIPleEk

[6666]

Can you disconnect the switches ?

[Borisimo]

Hi 6666,

do you mean take them off and see if it affects anything? I can easily chop them and reconnect later.

[baum7154]

I think that is what he is suggesting and this is what I would do too.