开云体育

Hello,

So, I've bricked my FT-817 while trying to install a digital SSB filter
in it :-/ Not entirely sure what went wrong, most likely I accidentally
shorted the filter's intended input-voltage wire to the chassis - but
the upshot is that while the radio still turns on the text on the
display (NOT the backlight, i.e. it's unlikely to be a PLL issue)
blinks, neither RX nor TX works, and the voltage between TP1084 and
ground is in the order of 1.5V rather than the expected ~13V. All of
this with the radio powered from a 13.8 VDC PSU, by the way.

Anyway, having assumed I blew the power-on circuitry of the radio I
replaced Q1104 and then Q1100 - to no avail. Which made me wonder, what
if the problem is not with these two transistors but with the POW-ON
signal driving Q1100? Maybe I have simply measured it wrong but it seems
to me that Q1100 remains reverse-biased regardless of whether
front-panel power is on or off.

With that longish introduction aside - does anyone know what the POW-ON
voltage in a working FT-817 should be, or perhaps could someone measure
it (TP1029 under the wide ribbon cable, if I remember correctly) for me?
Unfortunately I haven't got any reference hardware at hand and I really
would rather not order a replacement front panel for ~150 EUR only to
find out the radio still doesn't work.

Many thanks in advance!

73,
--
Marek M0JUR

Hi, I measured: the voltage on TP1029 (POW-ON) is exactly + 5V with ribbon cable connected. After disconnecting this cable, the voltage is 0V.
BR
Zbig SP3RNY


Od: "Marek Szuba via groups.io" <marek.szuba@...>
Do: [email protected];
Wys?ane: 13:21 ?roda 2022-09-28
Temat: [ft817] POW-ON voltage of FT-817ND

Hello,

So, I've bricked my FT-817 while trying to install a digital SSB

filter

in it :-/ Not entirely sure what went wrong, most likely I

accidentally

shorted the filter's intended input-voltage wire to the chassis - but
the upshot is that while the radio still turns on the text on the
display (NOT the backlight, i.e. it's unlikely to be a PLL issue)
blinks, neither RX nor TX works, and the voltage between TP1084 and
ground is in the order of 1.5V rather than the expected ~13V. All of
this with the radio powered from a 13.8 VDC PSU, by the way.

Anyway, having assumed I blew the power-on circuitry of the radio I
replaced Q1104 and then Q1100 - to no avail. Which made me wonder,

what

if the problem is not with these two transistors but with the POW-ON
signal driving Q1100? Maybe I have simply measured it wrong but it

seems

to me that Q1100 remains reverse-biased regardless of whether
front-panel power is on or off.

With that longish introduction aside - does anyone know what the

POW-ON

voltage in a working FT-817 should be, or perhaps could someone

measure

it (TP1029 under the wide ribbon cable, if I remember correctly) for

me?

Unfortunately I haven't got any reference hardware at hand and I

really

would rather not order a replacement front panel for ~150 EUR only to
find out the radio still doesn't work.

Many thanks in advance!

73,
--
Marek M0JUR

On 2022-09-28 20:15, Zbigniew Olszanowski wrote:

Hi, I measured: the voltage on TP1029 (POW-ON) is exactly + 5V with
ribbon cable connected.

Okay, looks like something is indeed broken on the front panel because I
don't get anything even close to that.

After disconnecting this cable, the voltage is 0V.

Makes sense, no ribbon cable -> no power to the CPU - no POW-ON signal.

Thanks a lot for your help!

--
Marek M0JUR

The front panel has it's own 5V regulator (Q4013), totally separate to the radio's 5V.
Regardless of the CPU working, while the power switch S4002 is held on, The 12V is connected to the regulator by fet Q4001 via diode D4011.
You can probe the switched 12V and the panel 5V easily from the top side at D4011 and Q4013 (corner by big electro)