Black Jupiter 2000 Function generator circuit.

[Yorkie]

Hi David, Thanks for replying.
I used a 0.1uF 1Kv cap to hook up to aerial on u650. I was following the instructions as per trader info as you have said but due to no signal all was abandoned.
The radio plays on all bands I did the IF alignment by ear was quite a way out I was trying the RF alignment to see if there was any more improvement.
I have never done any restoration before this is my first so I am trying to learn as much as possible on this radio. I retired early through medical problems and needed something to occupy myself thats not too physical.
Tried this and got the bug.ha ha.
I bought an I/T Variac, scope and function generator 2 Dmm's other odds and sorts
to learn so I am on a steep learning curve with all equipment and components.
Regards, John.

Hi again John,

It's good news that you used an isolating cap because if you look at the output(s) of the Jupiter it has no protection and if you squirt high voltage into it, it would be curtains for transistors such as TR20/21, but that said, in a perverse way, even if that happened, they might thus become fast acting three-legged fuses and offer some protection to the rest of the circuitry.

When poking around with test gear it's so easy when for example intending to connect to the grid of a valve, to inadevertantly touch the wrong pin (anode for example), and squirt high voltage into unprotected test gear circuitry, hence, the 0.1uF cap which you wisely used. At least in the Pilot U650, you cant mistake the grid of V1&3 as it's the top caps.

I think that if you first focus on the circuit on 'page 12'- the Triangle and Waveform Shaping Circuits' - you'll see that at S10, S11 and S12 there should be square, sine and triangle waveforms at those points respectively. If you hook up tyour scope and are lucky, and there are those waveforms, the faul lies in the output amplifier circuitry on page 11. If there are no waveforms at those points, you'd need to check for signs of life with your scope at places such as TP9 and other test points, which are there to help you pinpoint the likely area of the fault(s).

Not an easy task for anyone without the manual, but hopefully you'll be able to pick your way through it. Easy to get disheartened, but it's all good experience!

You've got quite a nice bit of test gear - I'd suggest an RF signal generator would be a good addition to your arsenal, and if you haven't already made one, a lamp limiter.

Best of luck John.