My DSO 138 won't work

[Hextejas]

The screen comes on but it is white.
Some of the readings are
V+ 8.28
V- .218
AV+ 4.9
AV- .793
VB2 base 0
VC2 collector 8.29
VB1 base 8.29
D1+ .213
D1- 0
R40 0

Please tell me what to do.

Regards

[MNTech]

Have you done Step 2 A? That's the one where you check the 3.3V at TP22 and short JP4 if the voltage is OK.
The 3.3V powers the microprocessor which puts pulses into R40 to drive the voltage inverter.
Your readings indicate you are missing this signal.

[Hextejas]

Have you done Step 2 A? That's the one where you check the 3.3V at TP22 and short JP4 if the voltage is OK.
The 3.3V powers the microprocessor which puts pulses into R40 to drive the voltage inverter.
Your readings indicate you are missing this signal.

Well tp22 is ok but I forgot jp4. Let me do that and get back to you.

[Hextejas]

Hooray, it works !

When adjusting, the C6 trimmer, it didn't seem to do anything. Is that normal ?

Thanks

[MNTech]

The effect of C6 is much less than C4.
On my DSO138 the corner of the trace can be varied from square to a spike about 1/4 of a division high.
As long as the corners are reasonably square the scope will work just fine.