Search found 78 matches

by davef
Sun Jan 03, 2016 5:09 am
Forum: DSO138
Topic: DSO138
Replies: 20
Views: 24037

Re: DSO138

Ah, no trace at all!

Is the timebase on "Running" or "Hold"? Try switching from auto to normal and single.
by davef
Sat Jan 02, 2016 10:46 pm
Forum: DSO138
Topic: DSO138
Replies: 20
Views: 24037

Re: DSO138

Did you try all switch positions? You could then try the "finger test" on various points working towards to the ADC input. Refer to schematic.
by davef
Wed Dec 30, 2015 4:27 am
Forum: DSO138
Topic: New kits - 13803/4K - F/W .050
Replies: 43
Views: 51557

Re: New kits - 13803/4K - F/W .050

Just like to add my thanks for -050. Upgraded a JYE unit bought from Banggood and certainly improved the noise issue.

You are also providing excellent support for this product.

Regards,
davef
by davef
Tue Nov 03, 2015 9:12 am
Forum: DSO138
Topic: V- on TP25 is -10.42V
Replies: 3
Views: 5717

Re: V- on TP25 is -10.42V

The -5V regulator is rated to take up to -20V on its input.
by davef
Sun Nov 01, 2015 8:00 pm
Forum: DSO138
Topic: V- on TP25 is -10.42V
Replies: 3
Views: 5717

Re: V- on TP25 is -10.42V

I suspect the tolerance on this reading is quite "loose". Mind read a bit high.
by davef
Sun Nov 01, 2015 7:57 pm
Forum: DSO138
Topic: Troubleshooting Internal resistance
Replies: 4
Views: 6715

Re: Troubleshooting Internal resistance

Input on DC coupling will depend on which SEN1 position you are on.

I think either your haven't done the Probe calibration correctly or you have wrong component values around the input circuit area. Does adjusting C4 make a difference at step 4?
by davef
Wed Oct 14, 2015 11:28 pm
Forum: DSO 112 & 112A (Coral)
Topic: bottlenecks in sampling rate and bandwidth
Replies: 5
Views: 9296

Re: bottlenecks in sampling rate and bandwidth

Use higher speed processor will increase through-put ...
or DMA?
by davef
Sat Oct 10, 2015 1:01 am
Forum: DSO138
Topic: 9V power adapter issues
Replies: 12
Views: 21487

Re: 9V power adapter issues

1) As long as it is 8V under load, I guess it would meet the requirement. 2) Don't see the step-up module you linked to. As long as it can supply the current required by the 'scope and doesn't over-load the USB port. 3)When you connect the two probe clips together you are connecting the input to gro...
by davef
Fri Oct 09, 2015 9:47 am
Forum: DSO138
Topic: 9V power adapter issues
Replies: 12
Views: 21487

Re: 9V power adapter issues

Thought I'd better check out how my 'scope behaves. Your last picture looks OK. You are probably at SEN1 at 10mv and SEN2 at X1, with the probe centre NOT connected to ground. The 'scope is just picking up noise in your environment. There is a switcher (SMPS) used to generate the -8V supply to U4 an...
by davef
Fri Oct 09, 2015 7:24 am
Forum: DSO138
Topic: 9V power adapter issues
Replies: 12
Views: 21487

Re: 9V power adapter issues

I was wondering if I could reduce it's noise.
When "we" figure out if the noise is radiated or conducted. If conducted then some proper supply bypassing.