FT-817ND with the most strangest defect ever, please help !!!

[DK1TCP]

About 2 years ago I got a used 817 as a gift. It worked, with some little flaws... On Christmas '22 I decided to change the leftside rotary-encoder (often turned "backwards" or jumped wildely) with an Chinese Part from my QRP-SDX-Project. It worked, but the resolution was bad. So I "recycled" the old encoder and changed it again: perfect - for about 2 months.

Then suddenly some strange muting effects occurred, mainly in the receiving stage. It turned out, that the signal going from mainboard to frontpanel-pot and back was temporarily interrupted. Fixed it with resoldering two pins on the 50-pole Connector (front panel). Hard work with degrading eyes...

Some weeks later (Jan. '23) it got worse. Muting occured in the TX-path, FM-Volume was not anymore settable, other strange effects took place. After reopening for the 15th time, it seemed that the flat cable was broken. Ordered a new one - happy for some days. Then TX-muting reappeared with the new cable...

So I decided to do some measurements. Test-cables from underneath the mainboard to the outside (analog scope HM-205) were soldered, another 20 or 50 times I disassembled the unit and got an idea, that I²C signals going to the mainboard were bad in the state of muting-failure. This was synergy after I got in contact with DC1MC and EA7EE from this board. KA7OEI pages were very helpful to understand what's going on.

To make the long story short: after a complete resoldering of the 50-pole connector on the front-panel and reusing the original flatcable (I broke the mainboard-connector at the 51th disassembling-session and had to replace it additionally) things are o.k. now since about two weeks! No EEPROM-change, no data-loss, no MCU-horror.

0.5 mm 50-pole was a challenge, but a specialist-soldering-guy in my surrounding did a perfect job. With my eyes I cannot do this anymore...
So I have a (momentaryly) perfect working FT-817ND again and want to share this experience with you in DC1MCs thread.

Thanks for your patience and vy 73 DK1TCP

[@rt]

Hi Guys 😀 818 owner here, and thankfully no problems yet,
but I’d love a copy of the dumped EEPROM, even from an 817nd.
I’d like to verify a few things such as if the 60 meter frequencies are
stored there, or in program memory.
I have also heard that the user’s callsign (for auto keying) is stored in
an area of on-chip EEPROM similar to some of the pics, as the callsign can
never be found on the stand alone 8 pin EEPROM.
Cheers!

[Nahim]

1. Remove the instrument cover.
2.Turn on the device and check the voltage of the power supply.
3. Then wait until the transceiver loses gain and at that moment change the transceiver supply voltage again.
the device is old and most likely the electrolytes are out of order.
This is a simple repair.