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40-190 RF Problems - Need Help
#1

I had to overhaul this set due to all the bad wiring along with a bad power transformer that was not original, 84 rectifier converted to 5Y3 and a bad audio output transformer. I found a power transformer that's good and I put in a 125B audio transformer from Radio Daze that I'm using pins 5 & 6 for the output with pin 5 to ground. Tried pins 1 & 3 as suggested but there's no difference in volume. I left the 5Y3 in place. The set has all new tubes, capacitors and resistors. Original filter cans and capacitor block restuffed. All of the IF coils read good. The #13 RF coupling reads about 5 ohms rather then the 3.5 ohms called out on the schematic. I've checked all my voltages but on the schematic no voltages are associated with the 7A6 2nd Det. or the 7C6 1st Audio. 7C6 plate is at 125Vdc. The voltages on the 1232 RF and the 6J8 (this is a run 4 set) are high. Plate of the 1232 is 205Vdc (S/B 160V), grid is 204Vdc (S/B 105V). Plate of the 6J8 is 208Vdc (S/B 180V if it were a 7J7) but the grid pin 4 is 83Vdc and the other plate is 168Vdc. S/B 80V and 150V respectively. Here's the schematic from NA and a pic of the chassis.
http://www.nostalgiaair.org/PagesByModel...013339.pdf
[Image: http://speakeasyradios.com/yahoo_site_ad...02_std.jpg]
The set is working but has problems. Station 620 comes in where it should on the dial along with 1260kHz coming in where it should at the higher end. Problem is 1260 comes in all over the dial and in the SW bands. I performed the "good radio next to my Philco radio" test and set them about 455kHz apart and there is reaction between the two sets telling me my oscillator is doing it's job. The radio seemed to align okay when I performed the alignment.

EDIT: I'm addidng this picture to show what I believe to be an anomally. I have an untouched 40-185 that works to make comparisons with. While ringing out my -190 I noticed that the bus on the pushbutton assy. reads 1.4 ohms to chassis gnd. except when the 1st PB is engaged then it reads open to gnd. My -185 reads open to chassis gnd. all the time. Could this be where part or all of my problem is? I can't find any errors in my rework.
[Image: http://speakeasyradios.com/yahoo_site_ad...09_std.jpg]
So I'm kinda stuck. I'm hoping someone can lead me in the right direction here. In the meantime I'm gonna go ring out all of my connections to make sure I didn't foul something up.
Thanks,
Pepper

"It's Nice To Be Nice To The Nice"
Major Frank Burns Mash 4077th


Messages In This Thread
40-190 RF Problems - Need Help - by Pepperoni - 10-15-2011, 02:47 PM
Re: 40-190 RF Problems - Need Help - by Pepperoni - 10-15-2011, 07:00 PM
Re: 40-190 RF Problems - Need Help - by Arran - 10-16-2011, 09:11 PM
Re: 40-190 RF Problems - Need Help - by Pepperoni - 10-16-2011, 10:09 PM
Re: 40-190 RF Problems - Need Help - by Arran - 10-16-2011, 10:19 PM
Re: 40-190 RF Problems - Need Help - by Pepperoni - 10-17-2011, 11:30 AM
Re: 40-190 RF Problems - Need Help - by codefox1 - 10-17-2011, 03:19 PM
Re: 40-190 RF Problems - Need Help - by 7estatdef - 10-17-2011, 04:08 PM
Re: 40-190 RF Problems - Need Help - by Pepperoni - 10-17-2011, 04:32 PM
Re: 40-190 RF Problems - Need Help - by Pepperoni - 10-18-2011, 12:49 PM



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