FeelTech FY3224S 24MHz Function Signal Generator: Manual Trigger has bugs

[mcmusic]

Hi everyone,

I have been playing around with my FY3224S  in the Manual Trigger mode.  My model seems to have some bugs here. I have attached some pictures showing the trouble.

At first I selected a sine wave of 1kHz. Then I pressed the “count” button three times to enter the Manual Trigger mode. In line 1 of the display I selected a count of 8 waveforms and pressed the button. 8 waveforms come out well on CH1. With 9 or 10 waveforms, the 2 latest waves come out wrong. From 11 onwards the output is ok. See pics A - D.

If I selected a square wave of 1 kHz instead of the sine, the 9th pulse is distorted (note the glitch to GND and an apparent longer “ON” time from 8-9 ms). See pic E.

If you select a slightly lower frequency, for example 0.995 kHz, the output shows a similar behaviour as with 1kHz plus an additional signal jump at 10.8 ms. See pics F - G.

At one time, the display got confused, showing “Manual Tri SINE”, but I forgot the exact button sequence to get this display. See pic H.

Can someone check these findings with his FY3224S? Do you get similar results?

Greetings,
mcmusic

[mcmusic]

Just a small Follow-up: The bug described above also appears in "CH2 Trigger" mode.

My adjustments for the attached pic J:

Ch2: 50 Hz, 1V Square.
Ch1: 1 kHz, 4V Sine.

With 5 presses on the Count button you reach the "Channel 2 Trigger" mode.
Line 1 shows CP_COUNT=10 (adjust the number to 10).

That means that every 20ms = 1/50Hz  10 Sine waves should be generated on CH1. Pic J shows that the very first burst is faulty, by the same reason from the previous post. The subsequent 15 bursts (and probably all thereafter) are as desired.

Hint: If you want to produce the same thing, adjust CH2 and CH1 as described. Then press the Count button 4 times, then you will have "Ext Trigger" in line 2 of the display. Then set your scope to trigger mode "Single" - it will wait for a trigger signal. Then press the Count button 1 more time and enter "CH2 TRIGGER MODE". My newly arrived Rigol Scope caught pic J after that.

BTW, the FY3224S has Firmware Rev. 2.0  2010-2014.

Greetings
mcmusic

[pascal_sweden]

Just out of interest, what oscilloscope are you using in the first set of screenshots? Very nice display!

[mcmusic]

Hi pascal-sweden,

it is a very nice but bulky Philips PM3320A. But it is starting to develop faults. It now has a severe low pass characteristic on Channel 2 for >= 5V/Div (below it works ok). This did cost me many hours wasted debugging time in another project. So far I did not dare to attempt the repair of this PCB-cramped cabinet. Maybe it is only an electrolytic capacitor that went bad?
I took the screenshots with my Canon S100 directly from the screen of the PM3320A.

Greetings,
mcmusic

[Lighthammer]

Got mine FY3224S 24MHz with Firmware 4.0

No issues with manual trigger.