Author Topic: FeelTech / Kuman FY6600 DDS Function Arbitrary Waveform Generator repair  (Read 381 times)

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Offline VE1IC

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I've posted this over at badcaps too.

Got it as a X-Mas present from wifey. Lasted about 30mins and then it was absolutely dead.
Checked the PSU and it was loaded down to next to nothing. Unplugged the main board from the PSU and all is O.k. on the PSU. Ahh! Main board problem!
Took the main board out and find a short at T2 (78L05) regulator between the input and GND pin. Took that out including the cap that is next to it and still have a short. I also measured shorts between C53 and C57. Took these out, took the 2 IC's under that heat sink out and still a short! Running out of options I decided to go old fashioned way hunting a short. Feed Power! Fed 5V 1.2A on the shorted line, doused half of the board with alcohol and success! SMD cap C81 bubbling! Replaced that with another cap the same size I found on a TV main board, put that in, soldered in all the parts I had taken out, reassembled it and I've got a working Function Generator.

So in short: If you have a Feeltech / Kuman FY6600 that doesn't work and the PSU is good, check C81 on the main board. It is under that little heat sink that is on top of of the 2 IC's.

Merry X-mas!

Offline The Radio Shop

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Re: FeelTech / Kuman FY6600 DDS Function Arbitrary Waveform Generator repair
« Reply #1 on: December 26, 2018, 07:18:32 AM »
Wow, Great job at hunting down the faulty component.
Must have been bad from the beginning.
Thanks for posting this unique bit of troubleshooting.

Using the brute force method like that really helps on the tough ones.
On older gear I use a low voltage battery on the rail. Then start checking the voltage as I move away from the battery.

The way you did it works a treat for those hard to read schematics or no schematic.

Thanks again for this valuable information.
Buddy kc4umo

Offline VE1IC

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Re: FeelTech / Kuman FY6600 DDS Function Arbitrary Waveform Generator repair
« Reply #2 on: December 26, 2018, 12:02:12 PM »
I thought you'd like to have this posted here. I only post in a few forums, that's it. The Fuction Generator works fine since the repair, no problems. I didn't have a schematic and didn't find one either. Usually these chinese thingies either work, do not work, or fail after a very short time. It is funny how a little tiny cap like this takes the whole thing down. Anyway... Buddy, if you think of it, I need that interface board (on that PM). Thank you! :)

Offline The Radio Shop

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Re: FeelTech / Kuman FY6600 DDS Function Arbitrary Waveform Generator repair
« Reply #3 on: December 27, 2018, 08:49:00 AM »
Cool deal.  I think I have seen a schematic for that model. I will have to dig around.
I will get in touch with you today on the board. PM me if you do not hear anything. So busy.
Buddy kc4umo

Offline VE1IC

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Re: FeelTech / Kuman FY6600 DDS Function Arbitrary Waveform Generator repair
« Reply #4 on: December 27, 2018, 10:37:21 AM »
You did find a schematic for it? Cool, hope you can upload it.  ;D
O.k. on that  board and I'll reimburse you off course.