GE 408 Radio

6/23/2009 8:22:33 PMJesse Hancock

Can someone Help me Im stumped.Ive replaced the electrolytics in several radios and never had the problems Im having now. I really am getting mad, I want to see this radio work,BUT Im unsure even after looking at the schmatic, where the rectifier tube is?
I see rect, noted in a part of the schematic, but its noted as a selenium rectfier? Im hoping that all the wires are hooked up correct.. Im really stumped. Can anyone help??? Will be willing to talk via phone if someone can email me with their number.. Or I can send mine..

6/23/2009 9:26:42 PMEdd

Sir Jesse. . . .

Indeed your set does use a selenium rectifier that is being designated as X1 on your schematic, placed at almost the

extreme right bottom corner.
Physically, on the set chassis, it is located at its OUTSIDE front of that chassis.

Sort of iffy as whether to use the set as it is, with that SR, or to replace it with an 1N4007 silicon diode, if so pull the selenium from circuit and change the R31 surge resistor upwards to an ~ 47-68 ohm value unit in order to enact a greater voltage drop. . . .thus ending up with the approximate voltage that the selenium rectum-fire was producing. The diode inherently has less of a voltage loss thru it than the selenium rect had.

Additionally, place an ~ .001-.0047@ 500-1kv rated ceramic capacitor across the 1N4007 diode, should a diode be used.

Assuredly, by now, you have ye olde filamentus lineamas restored now. . . .right ?

73's de Edd

6/23/2009 10:40:18 PMJesse Hancock

No edd, no filaments are lit. Its really really driving me nuts... HELP HELP HELP..

6/23/2009 11:21:09 PMRadiodoc

Jesse,

If you have a voltohm meter (VOM), check the filaments of the tubes. Check pins 4 & 5 of the 12AT7 and 19T8 and pins 3 & 4 of the other tubes. There should be continuity. Looking at the bottom of the tube(s) with pins facing you, pin #1 is the first pin clockwise from the wide gap in the pins. Any tube that does not have continuity between the filament pins will have to be replaced. All of the tube filaments are in series. If any tube filament burns out, no filaments in the other tubes will light.

Radiodoc
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:No edd, no filaments are lit. Its really really driving me nuts... HELP HELP HELP..

6/23/2009 9:31:33 PMRadiodoc

Jesse,

Your radio does not use a rectifier tube. Instead it uses a selenium rectifier. I believe it is mounted on the front of the chassis and is probably rectangular in shape and may either be black, orange, or red. You can measure the DC voltage from the lead marked plus (+) or a paint color to the common B- or chassis. The voltage will probably be around at least 110 volts DC if the rectifier is good. If the voltage is way low or not at all, then the selenium may be bad or the surge resistor attached to its input may be open. The selenium can be replaced with a silicon diode of say 1N4004 to 1N4007. The surge resistor may need to be increased in value to keep the proper B+ voltage as the silicon diode will not drop as much voltage across it as the selenium.

Radiodoc
*******************

:Can someone Help me Im stumped.Ive replaced the electrolytics in several radios and never had the problems Im having now. I really am getting mad, I want to see this radio work,BUT Im unsure even after looking at the schmatic, where the rectifier tube is?
:I see rect, noted in a part of the schematic, but its noted as a selenium rectfier? Im hoping that all the wires are hooked up correct.. Im really stumped. Can anyone help??? Will be willing to talk via phone if someone can email me with their number.. Or I can send mine..