Issues on Twintex TFG-3620E - Page 1
Forum section: electronics / testgear

author: tkuhmone
author_rank: Regular Contributor
timestamp: January 30, 2017, 07:01:03 am
content: Does anyone have here the mentioned function generator ? I have checked basic functionality, and found some strange behaviour. Some of these numbered items, I have talked to Twintex support. And couple of them- I am waiting for feedback. Did not found info of these, with Google...Twintex generator 3600 series:http://www.twintex.com.tw/webls-en-us/TFG3600ESeries.htmlReview articlehttp://www.ittsb.eu/TFG3620E%20AWG%20Review.htmlFirmware6000C-07-01-02 (no firmware updates)List of issues*******************1. Vpp vs Vrms changes-connect multimeter to output (Fluke 179)-set frequency to 50Hz sinewave (channel A)-set amplitude to 1Vrms sinewave (channel A)-activate output channel A-check level at output A - OK-deactivate output channel A-enter up cursor, to select one digit in volt reading for modification-> previous step changes Vrms to Vpp -> but the 1V reading stays on (1Vpp is not same as 1Vrms)-> to me this kind of functionality is strange???-> in other menu points where Vpp and Vrms are selected, the generator changes numerical voltage value immediately (if Vpp changes to Vrms)2. Typing mistakes in firmware, pulse waveform-Set waveform to "Pulse"-in display it reads "Pluse"-Twintex responded "thanks for reporting"3. Output pulse during power on & power -off-Oscilloscope shows very short pulse during power on (without output A activated). The similar pulse exist also at power off.-It goes to both sides (plus and minus) of voltage "rails".-this pulse could destroy some sensitive electronics (if hooked on the gen output when powering on & off generator)-purpose of the pulse is unknown...-see two attached images, screen capture on Tektronix2225 scope @output A, when no signal activated:---> 1V/DIV, 0.1s/DIV (power off)---> 1V/DIV, 10ms/DIV (power on)- response from Twintex was:"This pulse exist everywhere, even when we turn on and off the light in house. I sorry to say that in our technical capacity, it is un-prevented at this moment."4. Output sinewave distortedOutput A is activated as sine wave. Scope connected to output A (analog tektronix 2225 -> 50 MHz bandwitdh). Outgoing waveform has very short "notch" at sinewave each period. That is visible in the positive peak and negative peak at sinewave. It was respective to the 90 and 270 degree of aech period of sinewave. Duration is very short, maybe 10...20us. It looks like sine waveform is occasionally distorted... I tested same time again later, did not see it amymore. Not yet sure if warming up of generator made this one to disappear. I will try to re-produce it next time and take image of the scope display...5. Sinewave amplitude steps-output is set to sine wave (default 1kHz)-set amplitude to 1Vpp.-activate output A, amplitude now ok.-drive cursor from right arrow to amplitude digit of "0.1V"-try to increase output amplitude from rotating knob 1.0 -> 2.0 Vpp, using 0.1V steps.-when amplitude is changed from 1.6->1.7Vpp, in the actual output there is very short spike of huge amplitude, approx 16...18Vpp. Tested on screen with Tektronix 2225 scope. This spike happens same time when relay clicks inside of generator. This spike is enough to destroy input of sensitive circuits (!)-edit (2017.02.11): generator produces spike with all output waveforms (sine, square, triangle). Happens also in lower levels, for example when output is set from 160mVpp to 170mVpp.6. SI unit of second-select any of the waveform on output A-on the right side of screen, press once the "frequency" selection. Now period of signal is seen.-display shows incorrectly written "S" as unit of second. This "S" refers to Siemens (conductance)7. Amplitude menu item - millivolts RMS-select any waveform to output A-on the right side of screen, press once the "amplitude" button. Now amplitude selections (Vrms or Vpp) are seen on the bottom of screen.-one of these options is written as "mVrm" -> shall be "mVrms"8. Attenuator menu item - incorrect typing-select any waveform to output A-on the right side of screen, press once the "offset" button. Now amplitude attenuation setting are visible on the bottom of screen.-menu item is written incorrectly "Attenuater" -> shall be "Attenuator"9. Signal offset adjustment issues-set sine waveform to output A-> need to check this more, since on some occasion the offset / amplitude measurred -> does not match the value on menus...10. Typing mistakes in firmware, output phase adjustment-activate channel A to menu-on right side of screen, there is Wave button-press it once until "Phase" -item is seen-on the bottom of the screen, it is incorrectly typed as "CHA Phasic"-> same error seen also on channel B menugeneric questions*******************-Is it possible to manually update firmware at Twintex TFG-3620 generator ? From my previous contact to Twintex, I had no info of user firmware updates...edits**************2017.02.09: added current firmware info and link to a review2017.02.11: updated information on issues 4...92017.03.27: updated information on issue 3, images attached2017.04.10: added issues 10 & 11

author: tkuhmone
author_rank: Regular Contributor
timestamp: February 09, 2017, 10:52:41 pm
content: list continued...11. Output phase adjustment not constant-activate both channel A and channel B (normal sinewave ok)-when checked with both channels set 0 degree phase, they should be equal-it is seen on the scope that output on channel B, does not correctly track phase to output A - small difference seen bigger and bigger as time passes-> need to check more details on this (also user manual of generator)

author: tkuhmone
author_rank: Regular Contributor
timestamp: February 11, 2017, 02:42:56 pm
content: ...this post reserved for future use...

author: tkuhmone
author_rank: Regular Contributor
timestamp: February 11, 2017, 02:49:33 pm
content: Seems there is more problems found, when I look into more deeply of the Twintex generator functionality. At least the issues 3 and 5 are mostly scaring me - since there is a huge voltage applied to output in the case where user does not expect itAt least currently there seems no responses, is it really so that this Twintex is smaller company - that the products are less propable to see on the lab desks of hobbyists ?The function gen I own, is still usable - but user needs to very aware of the issues. And connect the circuit used _only after_ definitely sure that generator does not send any unexpected higher voltage spikes to output (even in a normal using scenario)...

author: tkuhmone
author_rank: Regular Contributor
timestamp: February 19, 2017, 04:27:07 pm
content: fyi,yesterday I opened the unit covers, being aware of it may affect warranty. But I take it as learning point :-) There is couple of separate boards inside. I have found a DAC (Analog Devices AD9708AR), FPGA from Altera Cyclone family, CPLD from Altera Max -family - plus many other chips :-) I will sometime later post images to a separate thread...

author: kcbrown
author_rank: Frequent Contributor
timestamp: February 19, 2017, 05:21:05 pm
content: Quote from: tkuhmone on January 30, 2017, 07:01:03 amClearly they hired the same guy to do their firmware that Rigol hired to do the DS-1054Z firmware!It also clearly ranks right up there with the worst bugs if the response to the corresponding DS-1054Z bug is any indication ...

author: tkuhmone
author_rank: Regular Contributor
timestamp: March 26, 2017, 10:35:51 pm
content: Checking the Twintex TFG-3620E ARB gen -> goes forward. I updated information on issue 3, see images attached to first post on this thread (screen captures at Tektronix 2225) Those pulses look to me too badDoes anyone know, if there is similar behaviour (to issue #3) on any other brands ARB gens, like GW instek AFG-2225 ?

author: tkuhmone
author_rank: Regular Contributor
timestamp: April 09, 2017, 09:45:13 pm
content: fyi,...added issue #10 (another typing mistake in firmware) to a list.Issue #11 could be related to the generator not being able to keep constant phase difference between outputs A and B (as mentioned it needs more investigating).