Home Forum XMEGA Xprotolab XScope shows 20V on empty channels
 Gabotronics Forum :: XMEGA Xprotolab
Welcome Guest   
 Subject :XScope shows 20V on empty channels.. 2017-10-11 10:47:05 
skostrub
Joined: 2014-02-01 03:37:50
Posts: 5
Location

My beautifull Xprotolab is broken.

Both channels shows 13V voltage (in meter or scope mode) and do not react on input signals.

Can someone  kindly point me how this can be fixed?

I tried to replace the nagative voltage genarator (according to the troubleshooting guide) with no luck - now it shows 20V...

IP Logged
 Subject :Re:XScope shows 20V on empty channels.. 2017-10-14 18:22:14 
ganzziani
Joined: 2012-04-02 15:42:39
Posts: 463
Location: Sarasota, FL
 
Do you have all the correct voltages? (-5V, 3.3V, 2.048V)
IP Logged
Gabriel Anzziani
 Subject :Re:XScope shows 20V on empty channels.. 2017-10-15 00:30:09 
skostrub
Joined: 2014-02-01 03:37:50
Posts: 5
Location

U4 OUT shows 0.54V (input is 5.1V and all capacitors are OK)

U1 pin 40 shows 0.27V (instead od 2.048V) pin 39 shows 3.3

U2 out shows 3.28V

 

tl064cdr pin voltages:

1   4.39V     8   1.95V

2   0.98V     9   1.95V

3   0.15V   10   2.03V

4   5.11V   11   0.54V

5   0.14V   12   0.64V

6   3.94V   13   1.05V

7   4.39V   14   1.25V

IP Logged
 Subject :Re:XScope shows 20V on empty channels.. 2017-10-15 14:30:35 
ganzziani
Joined: 2012-04-02 15:42:39
Posts: 463
Location: Sarasota, FL
 
Those voltages do not look good. I don't see the negative 5v nor the 2.048V. The negative voltage generator is bad and probably the 2.048V reference.
IP Logged
Gabriel Anzziani
 Subject :Re:XScope shows 20V on empty channels.. 2017-10-16 08:01:21 
skostrub
Joined: 2014-02-01 03:37:50
Posts: 5
Location

I've already replaced negative voltage generator (TPS60403DBV according to BOM), but the new one also does not show -5V.

So I thinks it can be burned after powering on. If so? what component can damage it?

 

I have one more TPS60403DBV. Is there a risk to burn it after replacement again?

Input is 5V - OK.

 

D1 LM4040D20IDBZ pin 1 shows 2.048V

IP Logged
 Subject :Re:XScope shows 20V on empty channels.. 2017-10-27 06:08:47 
agmihos
Joined: 2017-10-27 03:07:08
Posts: 6
Location
I suggest you the following:
First, while power is off, measure the following:
1) Resistance on charge pump output (pins 1,4) . If resistance is less than 10Ω then probably you have shortcircuit at the output (accententaly soldered together pins), or damaged charge pump. Less like to have damaged capacitors C26, C27. If you have accintentaly place voltage to AWG, may the problem caused by a damaged TL064 (U3)
2) Resistance on charge capacitor (pins 3,5) . If resistance is less than 10Ω between or by any other pin of charge pump, then you have damaged charge pump. Less like to have damaged to capacitor C25.
If no problem found, power up circuit.
1) Measure the input voltage of charge pump (pins 2,4). Should be 5V. If not, problem is before charge pump. Check for a broken PCB line. If voltage is over 5.5V then the problem is power supply.
2) Measure directly output voltage of charge pump (pins 1,4). If you found -5V then check for a broken line after charge pump. If no volt, then, while circuit is powered place an external power supply on -5V. Be careful to place correct voltage and polarity. Also, after test completed remember to cut first external -5V, and THEN xprotolab power supply. If current is high, then a cheap infrared thermometer can help you to find the damaged part.
IP Logged
 Subject :Re:Re:XScope shows 20V on empty channels.. 2017-10-29 10:11:03 
skostrub
Joined: 2014-02-01 03:37:50
Posts: 5
Location

Thanks a lot for your feedback!

1. Resistance on charge pump output (pins 1,4) - 3.2 kOhm

2. Resistance on charge capacitor (pins 3,5) 0.35MΩ C=3.3uF

3. Measure the input voltage of charge pump (pins 2,4) - 5.2V

4. Measure directly output voltage of charge pump (pins 1,4) - 0.5V

If no volt, then, while circuit is powered place an external power supply on -5V

Is it ok to place 5V from external source to charge pump ground and ground from ext. sourse to charge pump out?



[agmihos 2017-10-27 06:08:47]:

I suggest you the following:
First, while power is off, measure the following:
1) Resistance on charge pump output (pins 1,4) . If resistance is less than 10Ω then probably you have shortcircuit at the output (accententaly soldered together pins), or damaged charge pump. Less like to have damaged capacitors C26, C27. If you have accintentaly place voltage to AWG, may the problem caused by a damaged TL064 (U3)
2) Resistance on charge capacitor (pins 3,5) . If resistance is less than 10Ω between or by any other pin of charge pump, then you have damaged charge pump. Less like to have damaged to capacitor C25.
If no problem found, power up circuit.
1) . Should be 5V. If not, problem is before charge pump. Check for a broken PCB line. If voltage is over 5.5V then the problem is power supply.
2) Measure directly output voltage of charge pump (pins 1,4). If you found -5V then check for a broken line after charge pump. If no volt, then, while circuit is powered place an external power supply on -5V. Be careful to place correct voltage and polarity. Also, after test completed remember to cut first external -5V, and THEN xprotolab power supply. If current is high, then a cheap infrared thermometer can help you to find the damaged part.
IP Logged
 Subject :Re:XScope shows 20V on empty channels.. 2017-10-31 05:11:31 
agmihos
Joined: 2017-10-27 03:07:08
Posts: 6
Location

According to your measurements most likely your charge pump is dead.

Yes you can place voltage to the output, BUT ONLY if you first power up your xprotolab. After test remember to cut -5V prior to shut down, and off course to have the correct polarity.

Is an unorthodox method, but the only one left to do.

-5V is better to placed gradually, and if you are able to adjust maximum current, put about 50mA.

While -5V is externaly applied xprotolab should work fine.

Is unusual to burn a charge pump, especially two in a row. Maybe is a good idea to check your circuit connected to xprotolab, to find cause of damage.

IP Logged
 Subject :Re:XScope shows 20V on empty channels.. 2017-11-07 22:48:46 
skostrub
Joined: 2014-02-01 03:37:50
Posts: 5
Location

Thanks for a good idea with external -5V.

Device worked well, so I decided to replace the charge pump it did the job.

 

Unplugged chennels now show 0.0035V. Device works!

Is there a way to calibrate it 0? Didnt found that part in manual.

IP Logged
 Subject :Re:XScope shows 20V on empty channels.. 2017-11-09 06:46:11 
agmihos
Joined: 2017-10-27 03:07:08
Posts: 6
Location

Thanks for the credits!

I guess speaking 25 years of expirience on marine electronics repair! I was forced to develop some unorthodox methods to resolve hard issues. Some times I'm thinking to write a relative book!


The information you are looking for, is somewere in the user manual.

If I remember well you press K4 before power supply. Then appear few options, one of them must be it.

I guess you are going to calibrate it after charge pump replace.

IP Logged
Page # 


Powered by ccBoard