10-19-2018, 11:04 PM
Ouch on the IF, funny, I'm also a guy who has an isolation transformer, but seldom uses it.
Your accident is a reminder that isolating the hot chassis set not only saves a life but parts as well.
Sit down with the schematic and consider what happened when the AC (line) found its way to take out the IF, I think that more damage was done, possibly a resistor dramatically changed in value or an antenna coil has gone open, even though signals are being received but not well. Is the AVC circuit working?
I just hate it when you try to fix something and only make it worse.
I could tell you a story, just finished this week, how I "fixed" a gas stove. I wanted to improve the ignition and stop the pilot flame from blowing out during ignition. Some 110$ later, new thermocouple and new Junkers Zündelektrode, the spark still won't light the gas, so I'm still torching it. The blowing pilot stopped on it own, despite spending hours fabricating a draft baffle. Oh, well at least it works and I didn't damage the porcelain... I had to get the Zündelektrode from ebay Germany...
Other radio related shorty, nice AC/DC table radio just dirty worked great, decided to wash the filty back cover/loop. Yep, one of those copper foil embossed types. All done looks super, turned it on dead as a door nail. What, so I injected a signal, as the radio warmed, it improved slowly, noticed when I came in contact with the antenna circuit signals improved. I got a test loop and tack soldered. Wow Normal! Looked at the foil loop, yep still damp, into the oven cooked until well done, Reinstalled perfect!
Not that I have taken a lesson from a local ebay seller, he never touched the sets, wiped them down with, are you ready? Mayonnaise! Took the ebay pictures and always got $50 or more for his everyday table radios...
Oh, general replacement metalized caps have a very poor dv/dt rating, in fact they are not rated. A pulse, even one less than the voltage rating can rupture the metalizing and the cap can loose capacity. In an AC/DC set this can be the grid cap. on the output tube, a tone cap on the plate of the output or a noise bypass on the same plate. Consider the IF going open, severe noise pulse...
GL
Chas
Your accident is a reminder that isolating the hot chassis set not only saves a life but parts as well.
Sit down with the schematic and consider what happened when the AC (line) found its way to take out the IF, I think that more damage was done, possibly a resistor dramatically changed in value or an antenna coil has gone open, even though signals are being received but not well. Is the AVC circuit working?
I just hate it when you try to fix something and only make it worse.
I could tell you a story, just finished this week, how I "fixed" a gas stove. I wanted to improve the ignition and stop the pilot flame from blowing out during ignition. Some 110$ later, new thermocouple and new Junkers Zündelektrode, the spark still won't light the gas, so I'm still torching it. The blowing pilot stopped on it own, despite spending hours fabricating a draft baffle. Oh, well at least it works and I didn't damage the porcelain... I had to get the Zündelektrode from ebay Germany...
Other radio related shorty, nice AC/DC table radio just dirty worked great, decided to wash the filty back cover/loop. Yep, one of those copper foil embossed types. All done looks super, turned it on dead as a door nail. What, so I injected a signal, as the radio warmed, it improved slowly, noticed when I came in contact with the antenna circuit signals improved. I got a test loop and tack soldered. Wow Normal! Looked at the foil loop, yep still damp, into the oven cooked until well done, Reinstalled perfect!
Not that I have taken a lesson from a local ebay seller, he never touched the sets, wiped them down with, are you ready? Mayonnaise! Took the ebay pictures and always got $50 or more for his everyday table radios...
Oh, general replacement metalized caps have a very poor dv/dt rating, in fact they are not rated. A pulse, even one less than the voltage rating can rupture the metalizing and the cap can loose capacity. In an AC/DC set this can be the grid cap. on the output tube, a tone cap on the plate of the output or a noise bypass on the same plate. Consider the IF going open, severe noise pulse...
GL
Chas
Pliny the younger
“nihil novum nihil varium nihil quod non semel spectasse sufficiat”
