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Re: Power Up Test DSO 068
Posted: Sat Jan 30, 2016 2:42 pm
by jye1
Re: Power Up Test DSO 068
Posted: Sat Jan 30, 2016 3:11 pm
by bigxo
Thank You Very Much for the Jpeg.
bigxo
Re: Power Up Test DSO 068
Posted: Sat Jan 30, 2016 6:45 pm
by bigxo
The U2 Pins are giving the following readings. SW3 Reads the following.
Pin 4 is -4.9V Pin 1 is 0
Pin 5 is 0 Pin 2 is 0
Pin 6 is -1.2V Pin 3 is 0
Pin 7 is 3.5V Pin 4 is 0
Pin 8 is 4.9V Pin 5 is 4.9V
Pin 6 is 0
Pin 7 is 2.5V
Pin 8 is 0
Is U2 Bad? Looks like Pin 7 to Pin 6 is dropping voltage but Pin 7 to Pin 5 is open?
Thanks for the Help
Re: Power Up Test DSO 068
Posted: Sat Jan 30, 2016 6:58 pm
by bigxo
Sorry for the screw up here is what I read.
U2 Readings Pin 4 is -4.9V, Pin 5 is 0, Pin 6 is -1.3V, Pin 7 is 3.5V, Pin 8 is 4.9V
SW3 Readings Pin 1 is 0, Pin 2 is 0, Pin 3 is 0, Pin 4 is 0, Pin 5 is 4.9V, Pin 6 is 0, Pin 7 is 2.5V, Pin 8 is 0
Is U2 bad it looks like it drops the - side Pin 6 but not the + side Pin 5????
Re: Power Up Test DSO 068
Posted: Mon Feb 01, 2016 10:15 pm
by Jonathan
I have used 7-zip (freebie) on Windows 10.
Re: Power Up Test DSO 068
Posted: Wed Feb 03, 2016 7:18 pm
by bigxo
Your Troubleshooting Guide shows a picture of readings, here is what I read. What do you think I should do next? I Still need to know about Chip LM6172 (U2) What do you suggest ??
V1 0
V2 0
V3 0
V4 You show -1.6V with SW1 on Ground I read 3.5V
V5 You show -1.6 and I show -3.4V
+5V I read 5V
-5V I read -5V
AV+ I read 4.99V
AV- I read-4.96V
VB I read .6V
VT I read 2.6V
VA I read 4.97V
VEE I read 5V
Sysclk I read 2.5V
Vbus I read 4.9V
Re: Power Up Test DSO 068
Posted: Thu Feb 04, 2016 1:36 pm
by jye1
Please check resistors R9, R10, and R11 for soldering and their values. Looks something wrong with these parts.
Re: Power Up Test DSO 068
Posted: Thu Feb 04, 2016 4:37 pm
by bigxo
Ok I first took one end of R9,R10 and R11 loose from Board and I read
R9 .997K Should be 10K
R10 3.29K Should be 3.3K
R11 468 OHM Should be 470 OHM
Now I resoldered and read across the resistors
R9 .675K
R10 3.29K
R11 418 OHM
Now I checked the resistance to test points on either side of resistors.
R9 I read between AV- and U2 Pin 6 .683K
R10 Read between R9 & R11 and TP4 3.1K
R11 Read between Grd. and R0 & R10 417 OHM
Re: Power Up Test DSO 068
Posted: Fri Feb 05, 2016 2:45 pm
by jye1
V4 still the same? Please also check AV+ and AV- right at the pins of U2 if you still get wrong V4.
Another try. Please disconnect R9 to see whether you can make V4 zero.
Re: Power Up Test DSO 068
Posted: Fri Feb 05, 2016 3:58 pm
by bigxo
OK
V4 still reads 3.5V
I unsoldered one end of R9 and V4 read -17.3mV, The other end that was still hooked to the board read -4.9V.
I Re-soldered R9 and V4 went back to 3.5V ?????