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40-150 static but no stations
#1

Hey everyone,
I'm having fun with this one! I have gone over this set and replaced all the paper and electrolytic caps as well as all the resistors save for three originals that checked within 10% tolerance. Naturally I have also replaced all of the old rubber coated wiring. The set powers up and I'm getting static but no stations. The volume and tone controls seem to be working as I can change the output from the speaker. Also I pass a 456k
hz signal from my generator thru the set loud and clear either from the grid of the 6J8 det/osc or even the antenna terminal. My guess is there is a problem with the oscillator circuit. I've checked out the oscillator coil and all seems ok there. I swapped out the 6J8 tube that my 40-150 uses (not the 7J7 tube shown in Riders) with no change, and the voltages checked are very close to what's listed in the schematic. I'm stumpedIcon_crazy! 20 years of repairing copiers has left my electronic troubleshooting a little rusty!!! Does anyone have any ideas or tips I can try! Thanks!!
Kevin
#2

Well,

Since you obviously have a generator, did you try to pass any of the actual frequencies the radio should tune to through antenna input? Say, 1200kc in the Broadcast band when you tune to it?
#3

Well, after some detective work, I've got this thing working (sort of)! I am now picking up some stations on broadcast and shortwave, but they are way off track! Our local powerhouse station is WHBL at 1330khz doesn't come in until the dial is close to 1500khz and WTMJ at 620khz shows up around 700. So, my guess is the alignment is screwed up, but at least I'm getting something nowIcon_clap! I did clean up the bandswitch and I may have been working with the set in police bandIcon_redface! The decal on the cabinet is so worn I couldn't make out which setting was which. I'm still not getting anything on the preset buttons, but I'm guessing that's due to the alignment?
This is the first radio I've ever worked on that has pushbutton presets so i'm not familiar with them. my question here is- does the last pushbutton on the right have to be pushed in for manual tuning to work? There aren't any tabs to go by and I wasn't able to get any stations until I pushed that button in.
Kevin
#4

This is what I thought. Align it first.
#5

Pushbutton #8 (far right) needs to be engaged for the broadcast band to work. Also, make sure bandswitch is set in most "counterclockwise" position. The factory loop antennas are "tapped" types, and are critical for working correctly for good reception. Position of 3-position bandswitch selection as follows: Most counterclockwise: AM broadcast, middle position: old police band (non existant anymore), far right (clockwise) limited shortwave bands. Check your factory loop antenna, it is critical for these sets to operate properly.
#6

Thanks for your input guysIcon_thumbup! The set is playing much better now, and after 2 or 3 tries at aligning, the stations are where they should be. i still have to adjust the pushbutton presets and then on to the cabinet. Thanks again!
Kevin




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