01-20-2009, 01:36 AM
I have completed full re-cap on a customers Philco 47-1230. I cleaned the Push Button section, and phono switch, & all is working great.
Today, after playing the radio over 20 hrs since restoration working great on all bands, something weird happened. I attached the phono a.c. plug 2-pin connector to see if phono motor would turn, and let the old phono motor run for a short amt of time. After some help by hand, the old motor started turning. In the process of doing that, the radio quit working. I had the old phono mono input rca attached, but the tonearm not connected thru the old hi-imp transformer mounted in fnt bottom of cabinet.
Anyways, the radio receiver shut down, but still had some audio on higher volume. After tapping on the tubes, I found the n.o.s. 7R7 tube I just purchased and played over 20 hrs testing from AES was very microphonic. I replaced the 7R7 tube, and the Radio receiver started working again.
My question is this, did the turntable motor pass some AC current via orig input wire back into the chassis to take out the nos 7R7 tube? Since I replaced the tube, everythings working fine in the radio again. I have unplugged the phono ac line output plug from chassis, and when I engage the phono pushbutton , everything is fine with just the phono RCA input still connected. Now I can engage & release the phono button without any harm to the radio. I really dont think the prob is in the phono ac switch. For now, I will leave the phono ac connector disconnected altogether. Without pulling out the schematic again, this doesnt compute for me right now? Anyone ever had this prob happen before? Thanks for your thoughts, Im overlooking something simple here on the Philco 47-1230 chassis. Randal
Today, after playing the radio over 20 hrs since restoration working great on all bands, something weird happened. I attached the phono a.c. plug 2-pin connector to see if phono motor would turn, and let the old phono motor run for a short amt of time. After some help by hand, the old motor started turning. In the process of doing that, the radio quit working. I had the old phono mono input rca attached, but the tonearm not connected thru the old hi-imp transformer mounted in fnt bottom of cabinet.
Anyways, the radio receiver shut down, but still had some audio on higher volume. After tapping on the tubes, I found the n.o.s. 7R7 tube I just purchased and played over 20 hrs testing from AES was very microphonic. I replaced the 7R7 tube, and the Radio receiver started working again.
My question is this, did the turntable motor pass some AC current via orig input wire back into the chassis to take out the nos 7R7 tube? Since I replaced the tube, everythings working fine in the radio again. I have unplugged the phono ac line output plug from chassis, and when I engage the phono pushbutton , everything is fine with just the phono RCA input still connected. Now I can engage & release the phono button without any harm to the radio. I really dont think the prob is in the phono ac switch. For now, I will leave the phono ac connector disconnected altogether. Without pulling out the schematic again, this doesnt compute for me right now? Anyone ever had this prob happen before? Thanks for your thoughts, Im overlooking something simple here on the Philco 47-1230 chassis. Randal
