Hi. My testpoint readings on my DSO shell (Board ID: EPw30x7W -same as on startup screen) analog board are all wrong! There's no negative voltage anywhere on the analog board. Here are the readings I get:
Input: +9.27v
V+: +8.44v
AV+: +6.9v
V-: +4.14v
AV-: +5.8v
V1: +6.4v
V2: +6.4v
V3: +6.36v
V4: +5.20v
Yes, all positive voltages! I checked all connections between U5, U4, and U6, and they test good, and C8/C10/C11 caps are installed with correct polarity. I am getting +4.14V directly on pin 5 (V-) of U5.
Can anybody help? Is my U5 bad? Thanks in advance!
No negative voltages at any test point
Re: No negative voltages at any test point
SOLVED. Bad solder joint on ground pin (pin 2) of J2 on the analog board!
Re: No negative voltages at any test point
Now I don't see a test signal, all I see is a yellow line at the bottom of the screen.
My DSO board is PN 109-15001-00F, and the analog board has at least 1 part that is not on the PN 105-15001-00E schematic. For example, my board has an SMD R20, ~1K, which is between the probe center lead and R3/C4/R1.
EDIT: looking at a past post in this forum, R20 has been added to protect from overload.
Back to current problem: When I did the first power test on the mainboard before soldering I could see a signal. All buttons and rotary encoder are working, but I can't get a signal of any kind to show on the screen, there is always a yellow line at the bottom of the screen.
My DSO board is PN 109-15001-00F, and the analog board has at least 1 part that is not on the PN 105-15001-00E schematic. For example, my board has an SMD R20, ~1K, which is between the probe center lead and R3/C4/R1.
EDIT: looking at a past post in this forum, R20 has been added to protect from overload.
Back to current problem: When I did the first power test on the mainboard before soldering I could see a signal. All buttons and rotary encoder are working, but I can't get a signal of any kind to show on the screen, there is always a yellow line at the bottom of the screen.
Re: No negative voltages at any test point
I hope you finally found what what the issue on your side.
I had similar voltage issue (all positives, V- at about +4 V).
Your post helped me to figure out that one solder point was wrong (probably AGND on J2) - even though it looked normal.
I resoldered a few points and now the DSO works fine. Thanks
I had similar voltage issue (all positives, V- at about +4 V).
Your post helped me to figure out that one solder point was wrong (probably AGND on J2) - even though it looked normal.
I resoldered a few points and now the DSO works fine. Thanks