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g0hze snowy 18th Sep 2021 10:00 pm

Kenwood TS50.
good evening all, as title but this one is dead nothing happens when i/o button pressed. I have lifted filter and confirmed that supply voltage is getting to PA board.
It seems that the relay that powers the radio when i/o button pressed is non functioning, looking at the circuit diagram that relay powers up the AVR board giving 8v and 5v out, that is not happening.
i removed the AVR pcb and added power to the relay, it changes over, so that was discounted as a possible problem, i then attached supply volts to the relay contacts, i get supply volts ( 13.8v) across all 3 legs of the 8v and 5v regulators
including the ground pin, i changed the 8v reg, still the same, head now in a befuddled state, so i packed it up for tonight.
Can anybody untangle my grey cell or if they have met this problem before.
I have lost my smd caps so ordered some more but they arrive till late next week, just in case 1 or more of those have died, 0.1mf and 10mf 25vw electrolytic's.
As usual any and all advice greatly appreciated, Snowy

g0hze snowy 19th Sep 2021 8:37 pm

Re: Kenwood ts50
Update on TS50, it seems that the 7805 reg was shorted internally, replaced that and now have the correct voltages out of the AVR board, but, still no switch on from the front panel.
will be checking if 5 volts gets to the micro on the display board tomorrow.

SiriusHardware 20th Sep 2021 4:14 pm

Re: Kenwood ts50
I have one of these, working since bought in the mid nineties in my case but it is long overdue some kind of failure so I will follow your case with interest.

Check the tagged backup coin cell and if it is run down replace it, and then try a processor reset. With power applied to the radio and the radio off - as it seems to be - hold down the A=B button and try to turn the radio on with the front panel power-on switch.

g0hze snowy 20th Sep 2021 4:47 pm

Re: Kenwood ts50
Another update on the ts50, a couple of the via's required the small mod due to leaky caps, thin wire and soldered both sides, this has now got the display and the controls working, but, all is not good, have audio but no t/rx on any band, no additional current draw, so onwards and upwards.
replaced the back up button cell, although it was reading 2.98 volts i changed it anyway.
Thanks for your input SiriusHardware, have tried that no difference, got more voltages to check tomorrow.

g0hze snowy 20th Sep 2021 9:10 pm

Re: Kenwood ts50
can any of you learned gents that are (very) familiar with the TS50 tell me if D2 (led) on PLL board is supposed to stay illuminated, mine comes on at switch on then off within 0.5sec, i was wondering if this is a PLL lock lamp, if PLL not locked then that is why i have no t/rx on any band. I also (thought) i read somewhere that D5 should not be touched, this one has a leg cut so again wondering if that could be a problem.
On a brighter note the display is working and so is the menu, getting there slowly but surely, thanks in anticipation.

SiriusHardware 20th Sep 2021 9:24 pm

Re: Kenwood ts50

Originally Posted by g0hze snowy (Post 1408385)
can any of you learned gents that are (very) familiar with the TS50 tell me if D2 (led) on PLL board is supposed to stay illuminated.

If no-one comes back to you sooner with an answer I will take the lid off mine tomorrow (Tuesday) night and take a look. It's high time I did some basic checks, such as making sure that the battery has not started to destroy everything around it.

g0hze snowy 20th Sep 2021 9:59 pm

Re: Kenwood ts50
SiriusHardware, that's very good of you, i found that someone, the PO had soldered a button cell having scraped/filed the outer coating from the cell just to get a good soldered connection, where the back-up battery lives, that would have been ok but the proper back up batteries are still available and it looks much neater now. cheers and beers

g0hze snowy 20th Sep 2021 10:43 pm

Re: Kenwood ts50
Just found a note in the manual ref D2, off is locked, so looks like that is not the problem after all, so continue looking tomorrow.

Richard675 21st Sep 2021 8:50 am

Re: Kenwood ts50
There’s a very good video by Peter, (search) TRX Bench, which deals with the TS50 and its foibles in some depth.

Richard675 21st Sep 2021 8:53 am

Re: Kenwood ts50
Oops….that’s a youtube video. Peter has done a lot very interesting and helpful videos on amateur equipment. Well worth a look.

g0hze snowy 21st Sep 2021 3:44 pm

Re: Kenwood ts50
Hi Richard, yep been watching his video's for hints and tips

g0hze snowy 22nd Sep 2021 4:35 pm

Re: Kenwood ts50
looking for a unwell TS50 to use as a source of spares for my radio, some of the leaking caps have quite a mess of the boards. T.I.A.

M3VUV51 25th Sep 2021 11:30 am

Re: Kenwood ts50
i used to watch peter trx bench ,but found his vids contained too mutch waffle (why say 5 words when 10000 will do!).

SiriusHardware 26th Sep 2021 11:36 pm

Re: Kenwood ts50
Sounds a lot like me, unfortunately.

Snowy - sorry I can't help you with parts but I would be interested to know where / in which parts of the circuit you found these leaking capacitors as obviously any other TS50 of a similar vintage could be facing similar danger - although you did say your example had a regulator fault so it is possible that the caps in question may have suffered overvoltage.

g0hze snowy 27th Sep 2021 7:55 am

Re: Kenwood TS50.
Sirius, I think the leaking caps are a known fault on this radio, C1 on the lcd board was bad, but, i have sorted that now, C187 and the 3 x under the ribbon cable on the PLL pcb.
I also found that a bd135 had been glued to the underside of the pll board in place of the smd device that should have lived there, that 1 smd device was costed out at £6 each, perhaps thats why the bd135 had been used.
My faults are NO t/rx, all controls works as does the all the lcd segments and indicators, got plenty of audio and all the controls are now 'scratchless' ok not noisy when turned, so work is ongoing at the moment.

M3VUV51 28th Sep 2021 11:01 am

Re: Kenwood TS50.
Hi. I doubt it's your issue but is the wire from the PA board to the antenna socket intact? I had one break once on a TS-50, looked fine until I prodded it though.

73 M3VUV.

g0hze snowy 29th Sep 2021 10:10 am

Re: Kenwood TS50.
Hi, thanks for your input, i have had that filter board out a couple of times to check voltages on the PA board, so i have made ( and unmade) that connection a couple of times, when in TX i draw just a approx 1.5 - 2amps so the PA is not being driven by the pre-driver, no output from the pre-driver on the PLL board.

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