04-08-2014, 08:58 AM
Ditto on the 42 plate to the volume control. Thats about 300v there. I too reccomend for you to do some reading on some basic repairs. As much as anything to know where the high voltages are and what tube does what function. Here is a common sense book I read with a lot of info for the beginner: http://www.ebay.com/itm/How-to-Repair-Ol...3a8d1031e2 It explains things in plain english.
I have the same signal generator. Be aware - from the volume control forward, you need to use the AF output on the generator, ground to chassis, and also a cap such as a .022 in series with your output probe. You can inject this in several parts of the output circuit, incl the volume control and control grid of the 42 (not the screen grid which will have high voltage). You do have a schematic, dont you? You will need to adjust the af mod/output control on the gen to raise or lower the strength of the signal. Have the gen set to int mod/af out. See what you get. You should hear about a 400hz tone. You can hit the top connector (grid) of the 75 tube. If you dont get anything, remove the connector and try again. This is a direct shot into the audio circuit. If you now get something, you have a problem in the grid/detector circuit.
If you get something, switch your gen to RF. Seems your oscillator is working. Good. Go for your IF. You will need to set your gen to the IF frequency - it wont pass station freq's. This is 460kc. You may have to rock the freq adjustment on the gen back and forth to find, it could be out of calibration. Make sure your modulation is turned up at least 1/2 way, your selector is set for "int mod, rf course is hi, and, and fine is at least 1/2 way. Easy to blame something in the radio when as setting in your tester is wrong. Start probing backwards through your IF stages. You can hit the grid cap connector on the top of the 78 tube and see if it passes the signal. Disconnect the connector and inject directly into the tube of you dont get anything. If it does, go back to your 6a7 and try your IF signal. If that passes, try a station signal, such as 800kc. Make sure your band switch is set correctly.
Oh, also, if you are putting a cheap volt meter across your speaker, dont expect much. I usually see less than .1 volt on the Fluke (digital) meter. This is with the 400hz audio signal. The resistance (impedence) of the meter is very low. Do these checks and report the results. I am rebuilding a model 610 with is similar to the 60. I hope this helps some.
I have the same signal generator. Be aware - from the volume control forward, you need to use the AF output on the generator, ground to chassis, and also a cap such as a .022 in series with your output probe. You can inject this in several parts of the output circuit, incl the volume control and control grid of the 42 (not the screen grid which will have high voltage). You do have a schematic, dont you? You will need to adjust the af mod/output control on the gen to raise or lower the strength of the signal. Have the gen set to int mod/af out. See what you get. You should hear about a 400hz tone. You can hit the top connector (grid) of the 75 tube. If you dont get anything, remove the connector and try again. This is a direct shot into the audio circuit. If you now get something, you have a problem in the grid/detector circuit.
If you get something, switch your gen to RF. Seems your oscillator is working. Good. Go for your IF. You will need to set your gen to the IF frequency - it wont pass station freq's. This is 460kc. You may have to rock the freq adjustment on the gen back and forth to find, it could be out of calibration. Make sure your modulation is turned up at least 1/2 way, your selector is set for "int mod, rf course is hi, and, and fine is at least 1/2 way. Easy to blame something in the radio when as setting in your tester is wrong. Start probing backwards through your IF stages. You can hit the grid cap connector on the top of the 78 tube and see if it passes the signal. Disconnect the connector and inject directly into the tube of you dont get anything. If it does, go back to your 6a7 and try your IF signal. If that passes, try a station signal, such as 800kc. Make sure your band switch is set correctly.
Oh, also, if you are putting a cheap volt meter across your speaker, dont expect much. I usually see less than .1 volt on the Fluke (digital) meter. This is with the 400hz audio signal. The resistance (impedence) of the meter is very low. Do these checks and report the results. I am rebuilding a model 610 with is similar to the 60. I hope this helps some.
