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Hello fellow boat anchor enthusiasts. I have here a very clean FT101ZD Mk 1 recently donated by a colleague. It arrived with him with a known no TX fault. I have not done any TX tests yet. Just trying to get it to receive at the moment. The set only receives on AM - not on SSB / CW. There has been some work done on this set over the years so some red herrings may be in there somewhere. This set used to have RX on all bands but very unstable, (fast frequency jitter). I have been told that after pulling and replacing the three plug in boards, (RF unit, Pre-mix unit, Pre-mix local unit), the set went deaf to all but AM, . All co-ax connections checked OK and in the correct positions. Card slot pins all look fine. No busted tracks on pcb's.

Clues:
Clearly audible hiss in speaker on all non-working modes. AF PA good.
Very quiet SSB heard among the hiss with NB on and AF volume all the way up. Very unstable by the sound of it. Almost inaudible but it is there. Could just be induced across loom somewhere.
Dim control at full bright drops hiss volume a little bit. (12V rail).
All power rails check OK on Rect. A and Rect. B boards. 8V present on all mode settings at J1, AF pcb, pins 1,2,3 and 4.
3rd digit from left on display non functional, (Possibly Q10 or Q4 on display pcb - will tackle this later. Swapped segments and fault stays at position 3). Herring. It did this before going deaf.
When turning the RF gain with ALC off the AM RX is only present in one position. Increasing RF gain knocks out the signal again. There is only one "sweet spot" as it were.
AM signal sounds very over modulated. Better with ALC on.
Relays click in and out briefly sometimes when switching out of AM mode. (VOX? "clunk" through PA?). Possible herring.
Checked Q13, Q14, (FET), and Ge diodes D2 to D5 on AF pcb - all OK.
Continuity through relay on AF pcb OK.
There is a very slight hum in the speaker with volume down. This has occurred since set went deaf. 8V regulator on lower chassis side rail gets a little warm but nothing alarming. Steady 8V out for 12V input.
Clarifier seems to only shift one way on RX.
ATT switch scratchy but common to all modes, (I think), so doesn't explain lack of SSB / CW.
The pre-select control seems to need very little adjustment over each band to pull in AM stations compared to my Mk3. Fishy but also possibly non-herring.

Rotary band and mode switches cleaned and seem to be working fine. No crunching / crackling when wiggled.

Looks like more than one fault here. If I can get the SSB / CW RX back I can then tackle the frequency instability issue. Maybe it will even transmit one day!

Many hours spent with service manual and trying to understand all the frequency conversion stages in this set. Took me years to figure out what an IF actually is!

Very aware of 900V / 300V and how to discharge it before working on set. I'm 56 and still here!

Any input / advice most appreciated. I have a working Mk3 but loathed to start board swapping just for the sake of it. These sets are a real gem so it would be great to revive another one.

Thanks in advance. Have a good day everyone.

David, M0LFD