marconi 157 - Printable Version
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RE: marconi 157 - the picker - 11-26-2016
I only got it to work on rf and I got the loudest motor boating sound on pin3 of tube 6f6 and one of the speaker plug pins going to the output transformer
RE: marconi 157 - Phlogiston - 11-26-2016
OK. Now check the grids on the other tubes.
RE: marconi 157 - the picker - 11-26-2016
if you look back to my other comment on page 5 I checked all the tubes and there was no motor boating sound until I got to tube 6f6 starting from antenna back to tube 6f6
RE: marconi 157 - Phlogiston - 11-26-2016
OK, but to be clear, is the motorboating present at the grid of the 6F6?
RE: marconi 157 - the picker - 11-27-2016
motor boating very loud on pin 3 of 6f6 and not has loud on pin 5 and another question what should be connected to pin 8 of tube 6f6 has it looks like a wire has been cut off it
RE: marconi 157 - the picker - 11-27-2016
the more I look I think there is a miss wire on tube 6f6 so if I could get some help on what should be connected to each pin that would be great thanks
RE: marconi 157 - KCMike - 11-27-2016
Pin 8 should have R9 & C27
Pin 1 '' '' '' '''' '' No connection. but probably used as a tie point.
Pin 2 & 7 "" "" Filaments
Pin 3 "" "" C26, C29, & one side of output trans. R10 maybe ?
Pin 4 Other side of C26 & other end of output trans.
pin 5 " " " R8 & C25 & one side of field coil.
pin 6 " " No connection but probably used as tie point.
Some of the parts might not be connected close to the tube socket and you might have to follow a wire to find them.
I hope I got this right, eyes getting dizzy trying to follow and write it down.
RE: marconi 157 - the picker - 11-27-2016
here is my connections pin 3 .005 c-26 and it goes to one side of output trans pin 4 positive end of 20 mfd cap-29 and the other side of output trans pin5 .05 cap-24 and it goes to pin 4 of 6k7 also .01 cap-25 and it goes to pin 4 of 5y4 tube pin 8 has positive side of 25 mfd cap-27 and the resistors are right
RE: marconi 157 - KCMike - 11-27-2016
Is your C 29 a multi section cap? I'm seeing two C29s One at bottom of schematic from field coil to ground and one at the pin 3 connection which is the plate of 6F6G that looks like it goes to R10.
RE: marconi 157 - the picker - 11-27-2016
(11-27-2016, 11:02 AM)KCMike Wrote: Is your C 29 a multi section cap? I'm seeing two C29s One at bottom of schematic from field coil to ground and one at the pin 3 connection which is the plate of 6F6G that looks like it goes to R10.
I thought that but I looked everywhere for c-24 on the schematic and I think the one at the top next to the speaker is c-24 not c-29
RE: marconi 157 - KCMike - 11-27-2016
r10 could be tone control if you have one. If not, maybe that's why you don't have c29 at the plate of 6f6g. if c29 was multi section it would be one can or big paper capacitor with two caps in it and two wires coming out of it and the can could be grounded or have ground wire coming out also.
RE: marconi 157 - the picker - 11-27-2016
(11-27-2016, 11:35 AM)KCMike Wrote: r10 could be tone control if you have one. If not, maybe that's why you don't have c29 at the plate of 6f6g. if c29 was multi section it would be one can or big paper capacitor with two caps in it and two wires coming out of it and the can could be grounded or have ground wire coming out also.so do I make the changes you said or is what I wrote earlier right
RE: marconi 157 - KCMike - 11-27-2016
So far I haven't said make any changes just trying to figure out where everything is and if it's right.
Far as I can tell what you wrote earlier is correct, but I don't follow this, you wrote.. the pin 5 -.05 cap-24 and it goes to pin 4 of 6K7. I'm maybe just missing it but don't see it connecting to pin 4 of 6K7 on schematic.
RE: marconi 157 - the picker - 11-27-2016
my mistake it goes to pin 3 of 6q7
RE: marconi 157 - KCMike - 11-27-2016
Just to get back to you. Everything based on what you wrote sounds like its hooked up correctly.
So, I don't know what could be causing the motor boating or what you should change.