FY6800 (esp. rotary encoder and power supply)

[BassClef]

I recently acquired a used KKMoon-branded FY6800 signal generator.  Everything works well except for one thing. The rotary encoder sometimes skips backwards or forwards one digit. It's annoying, but usable. I'm assuming that the encoder is mechanical rather than optical. Probably the contacts inside are just dirty.

So, repair, replace, or leave it alone?  Is the encoder reasonably easy to clean? I have both a DeOxit equivalent, and some home electrical contact cleaner with oil. Or does cleaning it significantly risk ruining it? Is an equivalent part available in the U.S.? I can solder and unsolder reasonably-sized components.

Also, can the 6800 be run off of 5v only, such as a 5v linear wall wart or a power bank?  Or does it require 12v as well? I've read conflicting reports about this. I was thinking of installing a standard barrel connector across the 5v rails for alternative power (with AC mains disconnected, of course).

I must say, this little box may not be adequate for commercial electronics development, but I think it will serve me well for aligning and troubleshooting ham radio equipment. And it's been a great tool for teaching myself how to use my digital oscilloscope. Honestly, its newer descendants don't offer that much more for me. Especially since their prices have now risen to the same ballpark as UNI-T and Owon, and even bordering on Siglent and Rigol entry-level territory.

Thanks!
--Peter

[Zoli]

Encoder: I've changed mine to a Bourns PEC11L; I don't recall the exact model, but is easy to figure out. Low profile is important, the rest is taste(detent, resolution, different button).
Power supply: It requires +5&±12(5)V, analog recommended^*
The difference between the FY6800 and FY6600 is minimal(some opamp changes in the output circuit, IIRC), so for inspiration look in the FY6600 megatread(https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/).
A link to the recommended FY6600 mods in the megatread: https://www.eevblog.com/forum/testgear/feeltech-fy6600-60mhz-2-ch-vco-function-arbitrary-waveform-signal-generator/msg1353109/#msg1353109

^*I have a couple spare PCB's for DIY linear PSU; PM if interested.

[DaneLaw]

I dont have the FY6800 but the FY6900 and I always use powerbank or my scopes 5v socket to its USB-B input that are placed direcly to the motherboard and bypassing the PSU board..
Makes it also way more convinient when running it from its PC software' that the PC dataline also delivers the 5v power..

On the FY6900 it seems to be 5v and 12V, while on newer FY6900 rev. its seems to only be 5V, so it seems 5V is enough.

// Looks like its only 5v on the FY6900  3 wires 5v and ground and ground, and 12v aint used from the org PSU board.

Pictures from the FY6900 not the FY6800 so not sure how much that differs.

PSU rails from PSU part. (FY6900 not FY6800)

 

How effecfull are these contactcleaners for rotary encoders flipping/jumping values.?
In USA this "Deoxit" seems quite popular, is it short term fix in lack of exchanging & desoldering it completely?

[BassClef]

Thanks, all. I opened up my FY6800 yesterday. DaneLaw, the 6800 does use +5, +12 and -12. I tried connecting to USB on my PC, that doesn't power the 6800. I think I'll leave the power supply alone unless it actually causes trouble. I also have a TinySA, so I have an alternative, battery-powered signal source if need be.

Zoli, thanks for the encoder replacement part number. It appears the best match is PEC11L-4115K-N0020.  For anyone who might need it, the part I ordered (from DigiKey) is:
https://www.digikey.com/en/products/detail/bourns-inc/PEC11L-4115K-N0020/16356633?so=82435497&content=productdetail_US&mkt_tok=MDI4LVNYSy01MDcAAAGNKmJF0BpDmE6Oz2MOT5HYuMm0_nyWqnj2v4ryHPr25fJGP6OPRoXhPnT1FyB9IW2h15luNK2u_05Cu1dIEuOM9C623RQodWI1LrT9fca_

Bournes data on the encoder family:
https://bourns.com/pdfs/pec11l.pdf

[BassClef]

Deoxit is a "contact cleaner" and degreaser spray. There are many equivalents. The stuff I have contains Isohexane, Diflouroethane, n-Hexane and Ethanol. It's great for cleaning pots, multi-contact switches, etc. Of course it's best when the contacts being cleaned can also be physically accessed to clean off stubborn crud, say on a large rotary switch. But sometimes you can just flush the dirt and oil out of a part, provided there are openings for the fluid to enter and exit. In this case, spraying into what might be an opening the rotary encoder did nothing. So I'm replacing the part, per above.

[BassClef]

I was unable to unsolder the rotary encoder from the board.  The OEM solder (on the mechanical fastening tabs) wouldn’t melt. Then I flushed out the encoder again several times with contact cleaner.  That hadn’t worked before, but this time was the charm. I squirted the fluid down the shaft and absorbed it with a cloth as it dripped out an opening in the side of the encoder body. The encoder is now working perfectly.

[Zoli]

I was unable to unsolder the rotary encoder from the board.  The OEM solder (on the mechanical fastening tabs) wouldn’t melt. Then I flushed out the encoder again several times with contact cleaner.  That hadn’t worked before, but this time was the charm. I squirted the fluid down the shaft and absorbed it with a cloth as it dripped out an opening in the side of the encoder body. The encoder is now working perfectly.

I remember that I just cut out the old encoder, once I had replacement; removing the pins one-by-one is easy.