Author Topic: FeelTech/FeelElec FY8300S Quick Tear Down  (Read 4040 times)

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Offline grizewald

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FeelTech/FeelElec FY8300S Quick Tear Down
« on: January 15, 2020, 03:10:18 pm »
Yesterday, I received a new FY8300S arbitrary signal generator. When unpacking it, the first thing I noticed was that there was something rattling around inside the case! So, regardless of breaking any warranty stickers, opening up the case and finding what was rattling around was the first priority before applying any power.

The case is great fun to take apart as the two ends now clip onto the main housing in four positions instead of two, so it turned out to be quite a battle. Thankfully, the tool marks on the plastic will be hidden once I put it back together. While I have everything in bits, I thought people might appreciate some tear down shots.



Everything looks very familiar from the FY6900. The same power supply, a very similar mainboard (re-spun to add the third output channel) and the same, unsafe grounding modification.

The rattling turned out to be one of the screws which hold the fan to the rear panel:



When I went to remove the other three screws, I immediately understood why the first one had fallen out. The screws are way too short for the job and as they have conical starts (being self tapping) hardly grip the mounting holes at all.

The fan itself is a 12V fan which seems to be running on 5V. It's certainly quiet and runs all the time when the machine is plugged in unless it is turned off via the switch on the mains input socket. It blows air from the case to the outside, pulling air into the case via the slots in the lower half, which are all nicely free of flashing. The wires to the fan sit on top of the wires carrying mains voltage from the mains input socket.

Here's the main PCB:



FeelTech couldn't be bothered re-spinning the PCB again to add a socket for the fan and have simply tacked the fan's power wires to a nearby regulator (which is now under a tiny heatsink which it shares with another regulator).



As the wires to the fan are just flapping around in the breeze, it's only a matter of time before they snap off where they are soldered to the regulator.

Finally, here's the power supply board. It still has a glass fuse. On mine, the ceramic capacitor just to the right of the fuse is actually fitted. I've seen pictures of the supply in the FY6900 and that capacitor often seems to be missing for some reason.



There are a few things that need doing before I put it all back together:

1. Fix the mains input socket wiring to properly insulate and strain relieve all the connections.
2. Return the number of grounding wires between the power supply and main PCB to two instead of one.
3. Secure the fan power wires and fit screws of the correct length to hold the fan securely.
4. Provide a properly insulated resistive connection between PE and power supply ground.
5. Put some heatsink compound between the output op-amps and their heatsink.
6. The soldering on the NOS relays seems to have been done after the board was assembled. I guess nobody bothered cleaning the pins of the relays before soldering as some of the joints are hardly making a connection (as far as I can see through the layer of flux which wasn't cleaned off the board after soldering the relays and output BNC connectors).

Given that FeelTech have seen the criticisms of the power connector connections and the grounding arrangement from the FY6900, it's disappointing to see them repeating the same mistakes in the latest design. The way the fan has been added is amateurish to say the least.
 
« Last Edit: January 19, 2020, 08:19:41 pm by grizewald »
  Lord of Sealand
 
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Offline PKTKS

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Re: FeelTech FY8300S Quick Tear Down
« Reply #1 on: January 15, 2020, 03:25:15 pm »

no surprises.

For the  price? still a good bargain.

bottom line: I don't care unless totally bricked if
I can open the housing and fix easy tidbits.

Simple design -  fair price - some fun
no worries if i can ditch the seal and disregard warranty

Can not say that for instruments of other price class


Paul
 

Offline grizewald

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Re: FeelTech FY8300S Quick Tear Down
« Reply #2 on: January 15, 2020, 03:29:22 pm »
I've certainly no arguments with the fact that it represents good value, but it really doesn't cost much to do the mains input and wiring in a safe manner.

  Lord of Sealand
 

Offline PKTKS

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Re: FeelTech FY8300S Quick Tear Down
« Reply #3 on: January 15, 2020, 03:37:16 pm »
I've certainly no arguments with the fact that it represents good value, but it really doesn't cost much to do the mains input and wiring in a safe manner.

yep and  certainly some fun improving the noisy smps with a linear one

for my use? I don't even bother that much.
 Just some fast waves here and there without hassle...

Paul
 

Offline don.r

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Re: FeelTech FY8300S Quick Tear Down
« Reply #4 on: January 15, 2020, 05:17:50 pm »
Doesn't appear to be a huge improvement over the 6900 given the price difference. Mods will still have to be done to make it safe as well.
 

Offline Gregg

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Re: FeelTech FY8300S Quick Tear Down
« Reply #5 on: January 15, 2020, 07:09:42 pm »
There is a lot of room to put a linear power supply inside compared to the FY6600.  If my FY6600 dies, I may consider swapping the linear power supply I made into a FY8300 but I don't have any need for the third output.
 

Offline rhb

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Re: FeelTech FY8300S Quick Tear Down
« Reply #6 on: January 16, 2020, 02:39:50 am »
Sigh....  Why am I not surprised.

Given the almost non-existent customer support from F***Tech/F***Elec it's par for the course.

I bought a Keysight 33622A 120 MHz AWG out of frustration with the FY6600 which was at the time borked by V 3.0 FW.   Even a used unit from Keysight's ebay store was 35x the FY6600.  But it is quite simply incredible.  Less than 1 ps jitter and able to generate ~10 ns pulses with a nice Gaussian shape.

As for value, I'll try to find time to make some comparisons between the FY6600 and the 33622A.  The harmonic performance of the F***Tech is actually *very* good at low output levels.

In my campaign to get F***Tech to provide relief to forum members with borked V 3.0 units  I sent F***Tech a bunch of photos of the two units on my 8560A that were so similar you could not tell the two apart with the promise to post a more complete comparison if they took care of the forum members.  It took almost a year, though one forum member was himself part of the problem by not responding to emails about shipping info.

I had threatened to launch a campaign of complaints about the lack of safety approvals, so I find it very interesting that German customs seems to not be letting the F***Elec products into the country.  IIRC I did eventually make a complaint to the US product safety commission, but did not single out F***Tech. 

The thing I find rather intriguing at this point is forum members have put so much engineering time into correcting deficiencies that a competitor could build a better clone with relatively little effort.  With first rate customer support they could easily charge 50% more than F***Tech.

Reg
 
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Offline nctnico

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Re: FeelTech FY8300S Quick Tear Down
« Reply #7 on: January 16, 2020, 06:49:03 am »
Doesn't appear to be a huge improvement over the 6900 given the price difference. Mods will still have to be done to make it safe as well.
Well, there aren't any safety issues from a technical point of view. The mains wiring is rated for mains voltage use and the creepage / clearances are OK too.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline luma

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Re: FeelTech FY8300S Quick Tear Down
« Reply #8 on: January 16, 2020, 11:33:15 am »
[...]
I had threatened to launch a campaign of complaints about the lack of safety approvals, so I find it very interesting that German customs seems to not be letting the F***Elec products into the country.  IIRC I did eventually make a complaint to the US product safety commission, but did not single out F***Tech. 

The thing I find rather intriguing at this point is forum members have put so much engineering time into correcting deficiencies that a competitor could build a better clone with relatively little effort.

I think more intriguing is the length of effort you will go to to try and prevent the rest of us from being able to import cheap test equipment.  We're buying $100 AWGs, nobody is harboring any ideas about them being as safe or stable as a $5000+ unit from Keysight.
 
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Offline grizewald

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Re: FeelTech FY8300S Quick Tear Down
« Reply #9 on: January 16, 2020, 11:57:59 am »
Doesn't appear to be a huge improvement over the 6900 given the price difference. Mods will still have to be done to make it safe as well.
Well, there aren't any safety issues from a technical point of view. The mains wiring is rated for mains voltage use and the creepage / clearances are OK too.

Using a wire with low voltage DC insulation to link ground to protective earth while at the same time allowing that wire to come into contact with the switched mode power supply's HV components is a significant and genuine safety problem. As is the fact that the fan wires were also touching HV parts of the equipment.
I can't imagine having directly soldered mains wiring with no strain relief being allowed either.
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Offline nctnico

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Re: FeelTech FY8300S Quick Tear Down
« Reply #10 on: January 16, 2020, 01:51:24 pm »
Doesn't appear to be a huge improvement over the 6900 given the price difference. Mods will still have to be done to make it safe as well.
Well, there aren't any safety issues from a technical point of view. The mains wiring is rated for mains voltage use and the creepage / clearances are OK too.
Using a wire with low voltage DC insulation to link ground to protective earth while at the same time allowing that wire to come into contact with the switched mode power supply's HV components is a significant and genuine safety problem.
But it isn't. Look more carefully at teardown videos of other devices and you can see the wire used for the ground has a 300V rating.
Quote
I can't imagine having directly soldered mains wiring with no strain relief being allowed either.
It seems the wires are soldered through the holes of the inlet. AFAIK there is no requirement to have strain reliefs on internal wiring. I agree it would be nicer to have a piece of heatshrink over the pars with mains voltages but OTOH it makes it difficult to inspect the solder joints.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline grizewald

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Re: FeelTech FY8300S Quick Tear Down
« Reply #11 on: January 16, 2020, 02:17:37 pm »
But it isn't. Look more carefully at teardown videos of other devices and you can see the wire used for the ground has a 300V rating.

My mistake. Looking closely at the wire which goes to the earth, it does indeed have a 300V rating. But that's less than it should have to be safe against the rectified mains voltage which is present in parts of the switched mode supply.

I'll still be reworking mine to make the wiring acceptable to my criteria. 
  Lord of Sealand
 

Offline CDaniel

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Re: FeelTech FY8300S Quick Tear Down
« Reply #12 on: January 16, 2020, 08:11:46 pm »
And after teardown , can you check the jitter for square wave ? One of the issues with FY6600 ... if this is resolved than is not just an expensive toy and could worth the money
Power supply and other deficiences can be corrected , but sloppy firmware not .
« Last Edit: January 16, 2020, 08:14:52 pm by CDaniel »
 

Offline ArthurDent

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Re: FeelTech FY8300S Quick Tear Down
« Reply #13 on: January 17, 2020, 03:47:24 am »

Here's the main PCB:




One thing I noticed was that the oscillator has been changed from the 50Mhz one used in the FY6X00 models to the common 10Mhz, making it much easier to modify it from using the crappy little oscillator to a much higher stability OCXO. 
 
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Offline don.r

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Re: FeelTech FY8300S Quick Tear Down
« Reply #14 on: January 17, 2020, 06:12:45 am »
Now THAT'S an improvement I can admire.  :-+
 

Offline FeelElec

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Re: FeelTech FY8300S Quick Tear Down
« Reply #15 on: January 17, 2020, 09:17:15 am »
Dear customer, we are very apologize for the trouble and thanks for your suggestion. We could accept your suggestion and replace the screws. If there is any problem with the product, please feel free to contact us.
Email: service@feelelec.com


FeelElec
 

Offline nctnico

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Re: FeelTech FY8300S Quick Tear Down
« Reply #16 on: January 17, 2020, 10:48:24 am »
I spot a solder bridge in the close up image of the oscillator!
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline grizewald

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Re: FeelTech FY8300S Quick Tear Down
« Reply #17 on: January 17, 2020, 10:51:00 am »
Dear customer, we are very apologize for the trouble and thanks for your suggestion. We could accept your suggestion and replace the screws. If there is any problem with the product, please feel free to contact us.
Email: service@feelelec.com


FeelElec

It would be a good idea as they currently fall out during shipping. If I hadn't noticed something rattling, who knows what a loose screw could have done!
  Lord of Sealand
 

Offline grizewald

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Re: FeelTech FY8300S Quick Tear Down
« Reply #18 on: January 17, 2020, 11:02:59 am »
I spot a solder bridge in the close up image of the oscillator!

If you mean the 20 pin chip just above the unpopulated 10 pin header, it's actually an HC245 bus transceiver which does the level conversion for the TTL outputs. It seems to be an intentional link between pins 17 and 18 as it was done after the PCB was assembled.
  Lord of Sealand
 
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Offline grizewald

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Re: FeelTech FY8300S Quick Tear Down
« Reply #19 on: January 17, 2020, 11:10:39 am »
One thing I noticed was that the oscillator has been changed from the 50Mhz one used in the FY6X00 models to the common 10Mhz, making it much easier to modify it from using the crappy little oscillator to a much higher stability OCXO.

Well spotted! When I quickly looked at the output, I seem to remember a 10MHz sine wave being about 9.999991MHz when measured with my GPSDO timebased counter. Using a 10MHz crystal really does make it simple to add an external reference input.
  Lord of Sealand
 

Offline rhb

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Re: FeelTech FY8300S Quick Tear Down
« Reply #20 on: January 17, 2020, 07:24:10 pm »
That *almost* makes it worth getting one.
 

Offline grizewald

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Re: FeelTech FY8300S Quick Tear Down
« Reply #21 on: January 17, 2020, 10:34:49 pm »
And after teardown , can you check the jitter for square wave ? One of the issues with FY6600 ... if this is resolved than is not just an expensive toy and could worth the money
Power supply and other deficiences can be corrected , but sloppy firmware not .

Square wave at 1.32566Mhz. Solid as a rock!

  Lord of Sealand
 

Offline nctnico

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Re: FeelTech FY8300S Quick Tear Down
« Reply #22 on: January 17, 2020, 11:18:07 pm »
You need to look at multiple periods! A square wave is difficult for every DDS based waveform generator (and most digital ones are) unless it has a special mode for generating square waves (*). The problem is that a square wave period always needs to be a multiple of sample clocks. If the requested frequency isn't dividable by the sample clock then some periods will be longer and others shorter which shows up as jitter.

The older Siglent SDG1000 series for example had extra circuitry to turn a sine wave into a square wave to mitigate this problem (which wasn't without issues though).
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline grizewald

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Re: FeelTech FY8300S Quick Tear Down
« Reply #23 on: January 18, 2020, 12:48:29 am »
My mistake.

Here's a 9.32566MHz square wave. Triggering on the leading edge with persistence set to 10 seconds.



I'd be getting a thick trailing edge if there was jitter wouldn't i?
  Lord of Sealand
 

Offline grizewald

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Re: FeelTech FY8300S Quick Tear Down
« Reply #24 on: January 18, 2020, 12:52:16 am »
It's a different story if you wanted to use the generator's sync output though.

Ch1 is the same square wave, Ch2 is the sync output from the generator and the 'scope's trigger source.

  Lord of Sealand
 
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Offline nctnico

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Re: FeelTech FY8300S Quick Tear Down
« Reply #25 on: January 18, 2020, 01:02:47 am »
Those square waves look OK. What happens if you use pulse generation mode (if available)?
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline CDaniel

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Re: FeelTech FY8300S Quick Tear Down
« Reply #26 on: January 18, 2020, 03:37:38 am »
Square wave looks ok , but turn slowly the frequency to see if some "odd" values have jitter
If is jitter free inded it is abig step forward
 

Offline rf-loop

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Re: FeelTech FY8300S Quick Tear Down
« Reply #27 on: January 18, 2020, 04:21:15 am »
Dear customer, we are very apologize for the trouble and thanks for your suggestion. We could accept your suggestion and replace the screws. If there is any problem with the product, please feel free to contact us.
Email: service@feelelec.com


FeelElec

It is bit confusing. There reads FeelTech FY8300S

You are FeelElec and talk like you are from this company who make these.

FeelTech in China in Henan Province do not know this FY8300S at all in their own web sides  ( http://en.feeltech.net/  ) (sidenote, fun that company do not use even https ). There can not find at all find this 8300S model. I wonder how many copycats there (here) in China is for these... taobao etc is full of these or lookslikes fhat print front panel labels as Feeltech or Feelelec  because we live in a culture of imitation.
ETA: But downloads section there can find FY8300S manual and other materials.

So who/what is FeelElec and what is FeelTech who is original (or are they same) manufacturer for example FY6900 and then their webside in 6900 front panel read FeelElec. What is this "guess who..." game for. 

How about your products CCC. You do not care  C E  or UL or TUV or what ever but looks like you  do not care even CCC.  Who we hang after first bad happen with these electrical shits even if low voltage electronics parts are not so bad in price. 

China Compulsory Certification (CCC). The CCC certificate was introduced in 2002 and applies to imported goods as well as to Chinese products. Why this information is missing everywhere where FeelTech or FeelElec who ever these are are giving informations about their products. Is it so that you think about these things...so what...who cares. Later you may find that also in China you can not anymore do how ever just because sky is high and caesar is far away. 

Is it so that that your products do not meet even domestic standards what is today nearly like mandatory in China afaik and you need do sales so that no one is responsible, just like P2P makets. How you round over China Customs (yes I know it is still today quite easy but later more and more difficult after (noname) is fully integrated inside.
Some nice similarities with European Union C E...
"Failure to comply with CCC regulations will lead to goods being detained at the border or returned to the sender. Likewise, improper use of CCC licenses or printing a CCC-mark on products without certification will also result in fines and penalties." 

And

"The two most important elements of China Compulsory Certification (CCC) certification are product testing (products that are to be certified are sent to test laboratories in China) and factory audits (inspection of the product manufacturers by Chinese auditors). Once a certification is granted, it is valid for several years but must be maintained through annual follow-up audits."

Now, please show these products CCC and documents about audit.  And so that all your products are traceable to it.  I think it is simple because of course you have these.


also it is good take seriously one previous message: //Posted by: rhb, on: January 16, 2020, 11:39:50 am//
« Last Edit: January 18, 2020, 10:22:46 am by rf-loop »
If practice and theory is not equal it tells that used application of theory is wrong or the theory itself is wrong.
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Offline rf-loop

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Re: FeelTech FY8300S Quick Tear Down
« Reply #28 on: January 18, 2020, 10:51:58 am »
My mistake.

Here's a 9.32566MHz square wave. Triggering on the leading edge with persistence set to 10 seconds.



I'd be getting a thick trailing edge if there was jitter wouldn't i?

This do not look bad at all.

Normal way to measure jitter is measure pulse to pulse, (period to period)  jitter. It can do with scope what have low trigger jitter. Trig to rising edge but watch next rising edge. Also good to check example jitter inside period, example trig to rising edge and watch falling edge.
In data sheets jitter is typically pulse to pulse or period to period jitter. Mostly these are today told using jitter rms. But true circuit is many times critical for peak to peak jitter.  Of course manufacturers like write rms jitter because this number is more nice looking. It is very near zero rms jitter if generator generate million pulse 50ns period pulses with zero jitter and then one period is 70ns. Nice but our some test setup may fail totally even when our generator have very low, nearly zero p-p time jitter rms number. p-p jitter is very important in many cases. Long persistence with good trigger setup tell it after wanted time period. I have long time cricised companies, independent of brand class about these informations. System math produced time jitter need tell peak to peak specially because it is not at all random distribution and system designer naturally know it exactly and then can tell rms for sales advertisements if like. 

« Last Edit: January 18, 2020, 10:53:50 am by rf-loop »
If practice and theory is not equal it tells that used application of theory is wrong or the theory itself is wrong.
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Offline nctnico

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Re: FeelTech FY8300S Quick Tear Down
« Reply #29 on: January 18, 2020, 11:20:13 am »
Well... I don't think you have to expect stellar jitter performance from such a low cost generator so I really wouldn't bother measuring it extremely precise. The square waves are likely made using a sine wave to square wave converter (comparator) which may have issues at really low frequencies because the rise/fall times of the sine wave becomes to slow.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline CDaniel

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Re: FeelTech FY8300S Quick Tear Down
« Reply #30 on: January 18, 2020, 12:14:49 pm »
Normally the square wave is generated digital from FPGA , but an older FY generator has jitter like in your oscillogramme with trigger ... for allmost all frequencies except for some that divide exactly with the clock
« Last Edit: January 18, 2020, 12:19:02 pm by CDaniel »
 

Offline TurboTom

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Re: FeelTech FY8300S Quick Tear Down
« Reply #31 on: January 18, 2020, 01:31:28 pm »
On today's "Magic Pulse", "SiFi II", or whatever the manufacturer may call their version of edge accuracy improvement technology, the slopes don't consist of a single "step" of the DAC output (i.e. outputting a series of -1V samples and the next series of samples directly outputting +1V -- this would permit much faster slopes), but the edges are "stitched up" of a certain amount of samples, ususally 2..3 and the manufacturer makes use of the reconstruction filter to smooth that out to a "more or less" steep, homogenous edge. To compensate for the mis-match of the sample frequency with the signal frequency, the arrangement of these "slope samples" is calculated (or looked up) new for each edge.

As a result of this approach, you will always find some slope steepness wobble with these generators (which may be more or less pronounced on a certain instrument, I emphasized on it quite a little on my "rants" on the SDG6000X which permits outputting faster slopes in certain modes than what the reconstruction filter is designed for), yet with the zero crossing (or centerline crossing) of the signal being virtually jitter-freeand thus resulting in the very good phase jitter figures.

This approach may also lead to some ringing on the "plateaus" of the square (quite visible with the Rigol DG800 / DG900 series) and as it appears, with the AWG that's the subject here as well.

Did anybody test if this three-channel AWG permits outputting full length 8kSa arbitrary signals simultaneously on all outputs? To tell from the FPGA specs, this shouldn't be possible (only enough internal ram to store slightly more than 2* 8kSa, and I don't find any external sample memory attached to the FPGA - unless it's located on the other side of the PCB).
 

Offline grizewald

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Re: FeelTech FY8300S Quick Tear Down
« Reply #32 on: January 19, 2020, 08:01:29 pm »
That sounds like exactly what is being done on this generator. In the shot where I'm triggering off the sync output, I think you can see each edge of the square wave on channel 1 being adjusted slightly on each pulse.

The sync output is unadjusted, and the original 4ns jitter still appears to be present there.

I'll try installing the software and uploading a waveform of my own to check all three channels at the same time. Are there any features you think I should include in the waveform?
  Lord of Sealand
 

Offline edigi

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Re: FeelTech/FeelElec FY8300S Quick Tear Down
« Reply #33 on: January 21, 2020, 01:33:27 pm »
Thank you for the detailed tear down.
As a result, I've pulled the trigger on one of the FY8300S (financially it's a bad idea to read reviews  ;) ). It's on its way now.

Trading the jitter for interpolated edges (varying rise/fall time) is an acceptable compromise for me. I could not justify even the cheapest Siglent/Rigol generator so far (still significantly more expensive although much better DAC and probably logic as well) as I suspect it will see too little use with me, but it's good to have one sometimes.

It's a pity that they don't include a decent PSU even in this variant, but luckily there is plenty of space for a replacement (that I'm not very keen to do though).
It's really good that finally they use a standard 10 MHz clock (so that it can be easily replaced with a better one), although allowing for an external reference is really a missed opportunity.
For a little cost quite much value could have been gained...
 
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Offline grizewald

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Re: FeelTech/FeelElec FY8300S Quick Tear Down
« Reply #34 on: January 21, 2020, 01:50:09 pm »
Don't forget to give it a good shake when it arrives. You don't want a screw shorting out the supply or anything else first time you power it up!

I also noticed that the rear panel is just a little bit too thick and this makes it very difficult to connect a BNC connector to any of the rear BNC plugs. I'm not sure how I'll address that problem yet.
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Offline edigi

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Re: FeelTech/FeelElec FY8300S Quick Tear Down
« Reply #35 on: January 21, 2020, 02:16:55 pm »
It's pretty clear based on your review that one has to start with disassembly (any hint there is welcome so that plastic is not broken) and go through your fix list. Even if nothing is obviously rattling a screw can be stuck already where it should not or it can fall out later on as well unexpectedly. There is no point taking risks here.
Thank you for the fix list.
 

Offline grizewald

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Re: FeelTech/FeelElec FY8300S Quick Tear Down
« Reply #36 on: January 21, 2020, 02:41:34 pm »
It's pretty clear based on your review that one has to start with disassembly (any hint there is welcome so that plastic is not broken) and go through your fix list. Even if nothing is obviously rattling a screw can be stuck already where it should not or it can fall out later on as well unexpectedly. There is no point taking risks here.
Thank you for the fix list.

It's a pig of a thing to dismantle. The ends of the case snap on at the centre points both at the top and bottom and the sides. The plastic is fairly soft, so there's no risk of snapping anything, but you need four hands to release all four catches at the same time. In the photo below, I've circled the catches on the rear end panel.



Obviously, each catch has a partner on the opposite side, so all you need is two larger prying tools for the long edges and two much thinner ones for the side catches.
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Offline grizewald

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Re: FeelTech/FeelElec FY8300S Quick Tear Down
« Reply #37 on: January 21, 2020, 03:18:58 pm »
Oh, and don't forget the screw which holds the upper and lower halves of the case together. The head of the screw is hidden under the label on the bottom of the case.
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Offline edigi

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Re: FeelTech/FeelElec FY8300S Quick Tear Down
« Reply #38 on: January 27, 2020, 09:03:04 pm »
Due to super fast shipping I've already received the device and have naturally disassembled.
There is a neat trick for this and you need only 4 small coins (the smallest that you can find, in case of the front side only 2 can be used due to the handle). Gently push the middle of the case inwards and push the coins in (see picture). After this, push neighbor coins away from the device (or top/bottom coin + flat type of screwdriver in case of front). Only 1 minute is needed to completely disassembe the case (naturally without grizewald exploring where the catches are it would have been very hard).

Nothing has fallen out but the fan is not rotating either... It has supply power so probably it's faulty (DoA). What I've noticed that the mains cable is very loose, almost falls out so a good fixing would require replacing the whole mains socket (if I knew where to buy one exactly the same size)...
I can understand the safety concern of the forum members: the PE (Protective Earth) wire is probably failing to reach the minimum cross-section requirement even for enclosure (although I could not find what it is in EU) it's so thin.
As I could not see how to make a final solution I've just used hot glue gun to stress relief the wires and prevent the fan or the screws falling out.

Unfortunately the rear BNC connectors are way too short (as noticed already in some posts) and it's not easy to fix it since the case probably supposed to fix them in place. Without making the plastic thinner however there is a huge risk that either the BNC socket breaks or the cable plugged in breaks. So I had no other choice but to use my router (originally planned for wood...) as I don't have such large drill that would have been needed for this. Initially looked quite ugly, but when assembled it's barely noticeable.

Next thing was the quick check of the functionality. I like how the SW developers have made an efficient use of the small screen space. It's really good (just like the documentation). Most signals don't have jitter (with a quick check I have the impression that log signals are an exception). This is very good at this price point.
Frequency accuracy is however quite bad, even though it's still within specification (20ppm).  After switching on it's roughly accurate, but warm-up means roughly 100Hz drift at 10 MHz. What's worse is that changing signal level or signal shape or anything that changes the heat generated creates a drift in the Hz range. For a signal generator this is too bad.
One thing that would require SW fixing is the printout of the measured frequency.  It can correctly measure GPSDO 1 Hz output duty cycle, however it prints only 1.0 Hz for frequency, where it could print 8 digits as well (like 1.0000001Hz) as the resolution is clearly there.
I plan to replace the TCXO (?) with an OCXO (means separate PCB) if its startup current (0.55A @5V) fits into the budget of the 5V rail. The current TCXO (?) is 3.3V with square output. Unfortunately 2 of its pins (which have 3.3V) are close to a plastic socket so probably neither desolder station nor a hot air station is an option (Argh!.!.!). The pin that is close the closest chip is the output.

I've checked the modulation with PMR device using harmonics (thus square as carrier) and it works nicely if radio is put close to the generator.

If the developers are reading this some improvement ideas:
- Safety first, use decent PE wire and cable isolation
- Rear BNC socket is too short even with the supplied cable, it must be fixed
- Better stability reference and possibility for external reference is a must
- If the data is there use it for proper frequency resolution

All in all value for the price is OK for me but it could be improved so it needs no fixing by the customer. It clearly cannot compete with the more expensive devices nor is it probably made for that target.
« Last Edit: January 28, 2020, 08:41:13 am by edigi »
 
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Offline grizewald

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Re: FeelTech/FeelElec FY8300S Quick Tear Down
« Reply #39 on: January 27, 2020, 11:42:53 pm »
Nice trick with the coins, I'll give that a try next time I need to take mine apart.  :-+

With mine, I put the cut wire back where it came from as I had the correct crimp pins for the connector on hand. I just crimped some 24AWG wire in a new pin and soldered the other end of the wire to the original cut ground wire. Then I took a proper sized and insulated cable and connected that (with a 10K resistor inline) to the PE pin on the socket with a proper spade lug and soldered the other end to the two ground pins on the underside of the power supply. With a 10K resistor, I measured about 30mV AC between the outside of the BNC sockets and earth.

Like you, I noticed that the internal 10MHz timebase isn't anything to write home about, but then again, neither is the one in my HP 5334A - in fact, it's probably worse!

If you want to wire it up so that you can feed it with a proper 10MHz reference from a GPSDO, just cut the legs on the clock chip. Then there's no risk of melting sockets and you're hardly going to use or need the internal reference again if you can connect a proper reference signal.
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Offline edigi

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Re: FeelTech/FeelElec FY8300S Quick Tear Down
« Reply #40 on: January 28, 2020, 07:52:56 am »
If you want to wire it up so that you can feed it with a proper 10MHz reference from a GPSDO, just cut the legs on the clock chip. Then there's no risk of melting sockets and you're hardly going to use or need the internal reference again if you can connect a proper reference signal.

I'd not like to rely on GSPDO always and I'd rather have a stable than an absolutely accurate reference.
My aim for accuracy is somewhere in the 0.1 Hz range and the refurbished OCXO that I plan to use for this has voltage control with 10 Hz/V tuning sensitivity (because of this it's not good for any serious use) so if adjusted with a small trimmer it's probably good for a year or so. I have still not decided that if it worth the trouble of the external reference input as it would require some kind of signal detection and switchover.

With better stability references available nowadays the tendency is that even in case of more expensive devices the external reference input is the first victim of cost-cutting (a very unfortunate tendency btw.).
« Last Edit: January 28, 2020, 08:43:23 am by edigi »
 

Offline grizewald

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Re: FeelTech/FeelElec FY8300S Quick Tear Down
« Reply #41 on: January 28, 2020, 09:22:37 am »
I think I'll probably just use a switch to select between external and internal references and replace the internal reference with an OCXO. It will probably need an add-on power supply for the OCXO as I don't think the built in one has enough reserve to drive the OCXO's heater.
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Offline nctnico

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Re: FeelTech/FeelElec FY8300S Quick Tear Down
« Reply #42 on: January 28, 2020, 10:25:18 am »
Just best sure to add some ESD protection to the external input. A 100 OHm series resistor and a TVS diode for example.
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 
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Offline edigi

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Re: FeelTech/FeelElec FY8300S Quick Tear Down
« Reply #43 on: January 28, 2020, 07:56:47 pm »
It will probably need an add-on power supply for the OCXO as I don't think the built in one has enough reserve to drive the OCXO's heater.

It's hard to tell without having detailed technical specification of the generator.
I've checked my OCXO and it heats up much faster than I've expected. It uses 0.5A for around 45 sec and then it drops quite fast to 0.2A before 1 min. is reached.  That 0.2A is probably less than what is used by the fan (that I cannot measure since it's faulty).
If the fan is sacrificed (it's probably anyhow not very efficient even if it works, especially for cooling the opamps since they are in the front side of the generator) and use some ventilation holes instead it has to survive the higher load only for 1 min. or less.
I've calculated with an extra 50mA for stabilizing the voltage for the tuning input but that can probably pushed down if really needed.
Unfortunately I don't have much time for this before the weekend, but I don't see it totally hopeless.

If I have to replace the PSU it needs a dedicated PCB due to the screw hole constraints and that means weeks at earliest...(not that I would be in a hurry)
 

Offline edigi

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Re: FeelTech/FeelElec FY8300S Quick Tear Down
« Reply #44 on: January 29, 2020, 06:36:50 pm »
I just couldn't resist making a quick check of why the fan in my device is not working so I've desoldered it (not without surprise: I saw already earlier that one of the wires is soldered to a pin of a regulator, but I did not expect the other wire to be soldered to a small capacitor as it was hidden by the wire).

Checking with lab PSU the fan started to work from 6V up. I cannot really blame the vendor of that fan that it does not start less than half of its rated voltage...
Unfortunately I've also grossly overestimated the amount of current that can be gained by not using the fan. It probably does not use more than 30mA from 5V.
 

Offline grizewald

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Re: FeelTech/FeelElec FY8300S Quick Tear Down
« Reply #45 on: January 30, 2020, 08:44:07 am »
Interesting! The fan in mine is a Sunon and it starts up just fine at 5V.
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Offline edigi

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Re: FeelTech/FeelElec FY8300S Quick Tear Down
« Reply #46 on: January 30, 2020, 02:14:23 pm »
This is what I've received. Maybe they've run out of their supply or found a different, even cheaper source.
If I start it by hand it can keep spinning, but it cannot start by its own from 5V (I've checked this also yesterday).
Also when running from 6V the airflow it generates converges quite strongly to nothing.

Btw. I've also noticed that it's soldered to a different place in your picture. This seems to me a rather ad-hoc cosmetical than a real solution, so I'll probably vote for ventilation holes even if I'm forced to use a different PSU because of the OCXO.
 

Offline ronbot

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Re: FeelTech/FeelElec FY8300S Quick Tear Down
« Reply #47 on: August 29, 2020, 02:34:26 am »
I got mine a few days ago, some of the mentioned issues have been factory resolved.
The rear BNC's now have a stepped hole (recessed on the inside of the back cover), so that the connector protrudes properly now... no fitment problems with BNC attachment.

Here's a shot I just took for those wondering about jitter... (please excuse my phones camera... it has noise issues)
Gen set for 10.00MHz output:
Main trigger timebase: 100ns/div
Delayed trigger timebase: 5ns/div
Delayed runs 1080ns after main trigger
Showing Envelope of 500 samples

 


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