Pcsgu250 communication error

Instruments PC Oscilloscopes and Recorders
1

I have installed the pcsgu250 om my win7 64-bits, with the pcsgu250_winusbdrv2 drivers, without problem. Then i have installed the PcLab2000LT ver. 1.12.
The device is starting ok, but without any response on any channel, and without any output on the function-generator.
When calibrating it ends up with the message:“calibration failed” ending up with “communication error”, and when i try probe-test nothing happens.
Here is the calibration log:
Calibration results:

CH1 offset at 3V/div : 161 OK
CH2 offset at 3V/div : 161 OK
CH1 offset at 1V/div : 101 FAIL
CH2 offset at 1V/div : 101 FAIL
CH1 Y-position low 68
CH1 Y-position mid 68
CH1 Y-position high 68
CH2 Y-position low 63
CH2 Y-position mid 63
CH2 Y-position high 63

Anybody help???
regards Erik Nielsen
oz1ewr

2

The PCSGU250 may be defective.
Can you test it in other PC ?
In this thread there is one possible solution: viewtopic.php?f=10&t=14627

If no help, you can return the PCSGU250 for inspection/repair to your local Velleman dealer or direct to:

Velleman Projects Tech. Dept.
Legen Heirweg 33
9890 Gavere
Belgium

3

Thank you very much for a quick reply.
I tryed an other pc, same result. Then I lifted the cover on the pscgu250, and there i found, that the L5 smc was burned out totally. I found the schematic, and tryed to short-cut the L4, and then I burned the T8.

Well, i ques, that i wil be a new item on my wishlist.

But thanks anyway

regards Erik Nielsen
OZ1EWR

4

I’m sorry for the inconvenience.
It is strange that the L4 was burned out.
Maybe due to some defect in other parts of the circuit.

5

Again thanks for answering.
Sorry, it was not L4 but L5 wich was burned out for good. There is no value on the schematic, but i think it is a RF-choke, but do you know the value for it and the others unmarked coils on the circuit.
I guess, that the circuit around the T8 is a voltage doubler, generating the pos. and neg . 12V. Is that right???

I can see, that che circuit is drawing ca 400 - 500 mA from the USB, so there must be a very power-comsuming fault behind the power-supply circuit.

Any good ideas how to identifye the fault???

Regards Erik
OZ1EWR

6

[quote]Sorry, it was not L4 but L5 wich was burned out for good. There is no value on the schematic, but i think it is a RF-choke, but do you know the value for it and the others unmarked coils on the circuit.[/quote]The L1, L5, L6 and L7 are specified: SMD CHOKE 500mA, 600ohm @100MHz

[quote]I guess, that the circuit around the T8 is a voltage doubler, generating the pos. and neg . 12V. Is that right???[/quote]Yes, the circuit is voltage doubler.

[quote]I can see, that che circuit is drawing ca 400 - 500 mA from the USB, so there must be a very power-comsuming fault behind the power-supply circuit.[/quote]It is normal that the PCSGU250 can take more than 400mA when everything is working OK.

When the USB connector is plugged in, the current is about 130mA.
After starting the program and when the “Loading” disappears from the screen, the current is about 460mA.

7

You are very helpfull, thanks. I will work from here.

best regards.

oz1ewr

8

Now it works.
I have isolated the fault to the powermodule, by lifting the L6 and L7, and adding + and - 9 volt. All was running at once.
So now i make a substitute with two ICL7660 making two 10 volts from the usb, - and if i dont work, then a discrete external supply.
Regards
Erik Nielsen
OZ1EWR

9

I’m glad to read that you have isolated the problem and found a “workaround” to get the PCSGU250 working!
The root cause of the problem is still unclear.
It seems that for some reason the T8 was continuously ON.
In normal operation its base current should be pulsed by the PWR signal from the FPGA IC7.