570 help - Printable Version
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+--- Thread: 570 help (/showthread.php?tid=21375)
570 help - rjm - 05-30-2020
Working on a 570. For years had the intermittent problem of working or just squealing. Never knew what you were going to get. Gone over and over to no avail. Now it just makes this loud rumble. All resistors and capacitors are in specs. I isolated to the second detector tube. If all tubes are out except 80 and 47 its quiet. the moment I put the 2nd detector in it starts. Remove it and place all the other tubes in but not that one, its still quiet. Found the voltage to the plate and screen grid high way out from what Philco says. At a loss. Any one else had this problem?
RE: 570 help - morzh - 05-30-2020
Stupid question: do you have the multitube shield in place?
RE: 570 help - rjm - 05-31-2020
yes I do.
RE: 570 help - Steve Davis - 05-31-2020
Could be any component associated with the second IF transformer through the detector. If you short the grid of the detector to ground, does the noise stop?
Steve
RE: 570 help - rjm - 05-31-2020
yes if you ground pin 3 grid it stops also pin 4 . but not grounding cap.