Author Topic: FT-817ND with the most strangest defect ever, please help !!!  (Read 863 times)

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Offline DC1MC

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Hello everybody, I have a FT-817ND that I want to save, it has a most unusual defect that I've never encounter it: On all RX non-FM modes, the moment I chance the frequency, something happens and the signal strength goes like 3-40db down (still hearable, but barely) and the noise increases. It stays like this up until I change the mode or the band, that it returns to working OK, and it stay so forever.

 The mainboard is one of the latest model and I wasn't able to find a schematic/PCB for the version 005189I, the latest service manual I could find stops at version H.

 I#m really willing to pay for this schematic, but is nowhere to be found.

Also in desperate need of ideas.

  Many thanks for the help,
  DC1MC
 

Offline cdev

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Re: FT-817ND with the most strangest defect ever, please help !!!
« Reply #1 on: May 04, 2020, 10:20:31 pm »
Well, if it works okay some of the time its likely an easy, cheap repair, when you find it. Maybe the AGC circuitry is involved? Yaesu is still in business, why dont you try calling them up and asking them. It can't hurt, and there is a good chance they would know right away what the problem was and tell you. Ham related businesses are much more user friendly that way. I mean, I have no idea if they would but, what the hell.
« Last Edit: May 04, 2020, 10:24:01 pm by cdev »
"What the large print giveth, the small print taketh away."
 

Offline vk6zgo

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Re: FT-817ND with the most strangest defect ever, please help !!!
« Reply #2 on: May 04, 2020, 11:29:10 pm »
I would also suggest asking the same question on QRZ.com, or perhaps eham.com.
 

Offline trevatxtal

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Re: FT-817ND with the most strangest defect ever, please help !!!
« Reply #3 on: May 05, 2020, 06:57:57 am »
A very useful group at
https://groups.io/g/ft817/message/109368
Sigh up free and learn all about your 817.
I am not part of running of the group but signed up as I am a 817 owner
 

Offline DC1MC

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Re: FT-817ND with the most strangest defect ever, please help !!!
« Reply #4 on: May 05, 2020, 10:04:29 am »
I have contacted Yeaesu via their contact form, I will try to call them directly eventually, I doubt if it will be of any use as, like any other company, they don't care if there is no income comming, Apple set the industry standard on this stuff.

Their German authorised representatives quoted me way more than the device is worth (480EUR+VAT for mother board replacement only, no repair :wtf:), so not much to do here. After the bad experince with the last DE Yaesu repair center, I would not trust anymore at all, last time I got my unit back unrepaired, missing screws and with a broken battery lid latch :(.

I will try groups.io, maybe one will have mercy and could share the needed schematic or maybe some usefull ideas.

Many thans for the sugetions and advice and if by chance have the schematic please post a link or PM me.

 Cheers,
 DC1MC
 

Offline vk2jdh

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Re: FT-817ND with the most strangest defect ever, please help !!!
« Reply #5 on: May 06, 2020, 07:56:40 am »
On all RX non-FM modes, the moment I chance the frequency, something happens and the signal strength goes like 3-40db down (still hearable, but barely) and the noise increases. It stays like this up until I change the mode or the band, that it returns to working OK, and it stay so forever.

 

Sounds like the PLL unlocking or unstable. Check in with the forums suggested
 

Offline msraya

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Re: FT-817ND with the most strangest defect ever, please help !!!
« Reply #6 on: May 06, 2020, 09:54:37 am »
Hi!

Mine get a overvoltage and then PLL unit and some of the uC SPI bus strobe signals where faulty.
One of these signal controls the LPF or the IPO/ATT. So, yours can be also faulty in the SPI Strobe signal and when uC send freq information via SPI bus, it also change LPF or IPO or ATT.
After replace the PLL unit that was the problem with mine, it change mode or LPF when I change frequency  |O.

I need a new uC or a new control board. But unluckily, the repair boards were gone time ago.
New control boards that YAESU offer me are new, and I need to change also main board to be compatible, better to buy a brand new one.
So mine goes to the repair junk box.

By the way. Someone with a spare FT-817 control board to revive mine?
I hope this would help you.
Regards
Manuel
EA7EE
 

Offline dropkick

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Re: FT-817ND with the most strangest defect ever, please help !!!
« Reply #7 on: May 07, 2020, 01:20:22 am »
https://www.youtube.com/user/TRXBench  has a few FT-817 videos.  Might have something useful in them.

 

Offline DC1MC

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Re: FT-817ND with the most strangest defect ever, please help !!!
« Reply #8 on: May 07, 2020, 07:51:48 pm »
@msraya Bing, bing, we have a winner ;), in an access of frustration I've bought a "donor" unit with the front unit gone (no power-up) but the rest is working OK, so I've used the new main unit with my front panel, and surprise, surprise, the behavior is identical :(.

So now I have to units with bad front panels, one with f-up digital commands and a new one that doesn't start at all, I measure it and it's really strange, the MCU boots, but some port outputs are shorted to ground or the whole GPIO block G is fragged where PWR_ON and friends are.
Clearly, they seem to suffer from a kind of MCU rot, I had the same issue with a 6802 in a Tek scope, most likely due to repeated thermal stress the I/O buffers get fragged, I am that >II< close to do my own front PCB with a beefy STM32F7 with better menus and features, I can do the schematic and software very fast, the layout and production is what stops me |O.
And to make things worse, even if I can read the code from an old MCU, they are now unobtanium.

Oh well, in the worst case I will connect a Blue pill or Nucleo and do a Pfuscherei to allow at last PC control, transferring reliable the flex connector will be a pleasure.

I'm looking to see if there are some buffers on serial signals, maybe some pull-ups or downs may recover the panel with scrwed signals.

Cheers,
DC1MC

 
 

Offline DC1MC

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Re: FT-817ND with the most strangest defect ever, please help !!!
« Reply #9 on: May 30, 2020, 09:32:04 pm »
Just in case it may help somebody, here is the continuation of the FT-817ND story:

- From the previous episodes: I have two FT-817ND, one that works but has the issue stated in this topic (similar with @msraya) and another that was bought completely dead, not powering on.
As I've thought the MCU on the front panel is was dead or dieing on both I've explored a number of options, including replacing the MCU or redoing the front panel PCB. None of them proved to be feasible so I've got a new front panel PCB from an Italian YAESU reseller for 130EUR + 17 shipping to Germany.

The board arrived nice and shiny, and once connected to one of the units started immediately, by NOT WORKING, with a classical YAESU error by blinking the display text (not to be confused with the PLL unlock error that blinks the backlight), and having no RX or TX, the exact same error when tested on the other unit.

Trying ALL possible factory reset settings didn't change anything, except that immediately after confirmation "beep, beep", the device was running for something like a second, and then coming back to blinking and being deaf. All controls were working in this state, one could change bangs, set memories and so on, and the settings were memorized OK and saved during power off.

So because I don have yet a CAT cable, I've popped with the glorious Quick hot air station ;) the 24C64 I2C EEPROM and transferred from the dead board to the new board, instant repair. INSTANT SUCCESS !!!  :-DMM :clap:
The unit come alive without any issues !!!

So the new panel PCB MUST be loaded with the previous content of the EEPROM, either by replacing the new with the original or the original EEPROM must be dumped and reloaded via the CAT cable, this site has the theory and command set:
http://www.ka7oei.com/ft817_meow.html

And there are like a gadzillon of programs to do it, or one could write it's own script for dump and restore, as soon as I get a CAT cable I will tell how it works, right now is easier to move the EEPROMs but I think every FT-817(8) should have a memory dump for emergency situations when the old EEPROM dies or get corrupted.

But wait, there is more  :popcorn: !!!!

The dead board that donated the EEPROM was sitting there looking  :'(, so because there was nothing to lose, I decided to give it a full reflow, by doing drag (re)soldering of the MCU and all the other parts with my Metcal hoof tip and copious amounts of Louis Rossmann flux and 63/37 illegal solder ;) and I've also put a blank EEPROM.

Guess what, IT STARTED IMMEDIATELY !!!  ;D ;D ;D ;D

Also with a blinking display, like the new one first time, but I didn't switch back the EEPROMS, this one will be loaded via serial cable.

So now I have TWO working boards and the strange defect one.

As it seems the MCU is actually more resilient as it looks like,  and looking on the schematic it seem that the digital multiplexer 74HC139 or the two invertors there, may be the first victim, I will 'scope the digital outputs and inputs to it for glitches. Also it seems that the digital signals coming from the MCU to the TTL logic have a rather large resistor in series !!!, it may reduce the generated noise while switching, but it will definitely degrade the digital levels.

If there is a degradation of the signal path I will try to see if reducing the resistors values may help, and if not I will first reflow the parts involved and then I'll eventually replace the mux and inverters, they are really cheap and I need to exercise my hot air skillz  ^-^.
If this will solve the issue that I'll have an extra working PCB available to cure a poor FT-817ND, @msraya, if you still need one, let me know, you have the first choice.


 Cheers,
 DC1MC
 

   
 
 
The following users thanked this post: msraya, coromonadalix

Offline msraya

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Re: FT-817ND with the most strangest defect ever, please help !!!
« Reply #10 on: June 07, 2020, 03:36:59 pm »
WooW, good news.

I haven't had time to work in the PCB. The radio is sitting geting dust in a corner.
I don't think It can be working again, as my problem doesn't come from the multiplexer or EEPROM.
The control lines didn't work. By the way, I will try reflow as I dont have any to lose.
Thank You!

Manuel
EA7EE
 

Offline m3vuv

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Re: FT-817ND with the most strangest defect ever, please help !!!
« Reply #11 on: June 08, 2020, 08:57:01 pm »
typical yaesu garbage,built to a price not a standard,ive had a few yaesu radios,now i wouldnt have one in the shack even if it was for free.
 

Offline vk6zgo

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Re: FT-817ND with the most strangest defect ever, please help !!!
« Reply #12 on: June 12, 2020, 12:03:20 pm »
At the moment, I have four faulty Icom radios queued up for repair, compared to two Yaesu ones.

Currently functional, I have an ancient Yaesu & two Kenwoods which, "try as I might", I can't kill!

That said, they are all old radios, & I admit I like a lot of things about the Icoms.

My Icom 575A has a delightful intermittent, where it suddenly loses receive & transmit, sometimes on all modes, sometimes on just a few.
I found what looked a likely fault, fixed it, & all was good till the next time I turned it on.

Looks like I'll have to clear a few kilos of debris off the bench, drag the old Tek 7613 over, & really get into it.

If the OP's radio doesn't have the fault on FM, maybe the answer is in those functions which are not used in
FM, like AGC.
 

Offline rhb

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Re: FT-817ND with the most strangest defect ever, please help !!!
« Reply #13 on: June 14, 2020, 12:50:03 am »
Sigh...

After getting a 991A, I bought an 817ND for the lower power drain.  I'm still not licensed again and it seems I may have signed up for another F***Tech.

Reg
 


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