Scope not working

[ronm99]

Unit powers on, Menus work, all switches seem to work, the display changes reflect switch position.

Trying step 3, have connected test signal to scope input. I don't see a signal. Hooked my meter to signal, its 9990 Hz, 1.2v, so I believe signal is being generated.
Scopes show what looks like .1V noise??

Voltages all appear normal except V5.
V1: 0
V2 0
V3: 0
V4: 1.6
V5 3.5 *******
VA: 4.9
AV+: 4.9
AV-: -4.9
V-: -4.9
5V: 5
V+: 4.3
VS+: 4.2
SYSCLOCK: 2.4 (Note leaving probe connected to this pin will cause unit to power off.)
VT: 2.6
VB: .6
VBUS: 4.9
Where should I look now?

thanks,
-ron

[jye1]

It is suggested to do a quick "hand signal" test on the scope side first. Simply touch the probe tip with your finger and see if you can get activity on screen. Usually the higher the sensitivity setting the larger of the activities. If you don't see any activities check probe as well as the scope itself.

Similarly you can also touch the center conductor of signal input BNC connector and check activities on screen. By this way you can tell problem is with probe or in the scope.

Do the noises disappear if couple switch is set to GND position? If it is true the noises are pick-up noises. Otherwise they are internal noises.

Voltage V5 is not critical and can be ignored for the time being.

Touching SysClock could make the oscillator stop working. That is why it could reset the MCU.

[ronm99]

I installed the BNC connector, plugged in probe, no activity on screen. Tried DC and AC.

I really didn't expect anything, as I'd already tied scope input to test signal (Step 3 in instructions), and didn't see anything.

Not too concerned with noise at this point, I don't see square wave shown in step 3.

Any other suggestions? I don't have a scope, just a multimeter (v, ohm, Hz, etc..)

[jye1]

Please touch the points marked V1, V2, V3, and V4 with tweezers and see if you get activities on screen.

[ronm99]

No activity.

[jye1]

Does menu work? If you can access menu (by pressing ADJ) please perform Default Restore and try the tests again.

[ronm99]

Menus work, default restore has no effect.

I was able to get ahold of another scope and poked around a bit.

I tie the test signal output to signal input, and set it for 1kHz, 5V.
At V1 I see 1KH, 5v square wave as expected.

V2 at I see 1KHz, .5V square wave.
V3 is 0V. I would assume we need a square wave here.
AV+, AV- on the the op-amp (U1A) are +5 & -5.

Used meter and v3 appeared to be shorted to ground. Looked like one of the pads of R6 was touching switch body, resoldered r6 and now I see a square wave on display.

Doesn't appear to sync very well, but its a start.

[jye1]

You might want to adjust trigger level and see if it gets synchronized.