This radio was playing nicely. I putting it back into the cabinet and as I was I didnt realize it was still plugged in and BAM!! there was a small spark. Now I get no sound but a faint static. Checked all the tubes and they are all fine and I dont see anything obviously bad.
UGH! I unplugged the cord next to it that was the same color!
Joe

plugged-in but not ON ? doubtful that the output transformer would be harmed. you could easily check it with volt meter or ohm meter depending on your preference. most likely something touched under the chassis while you were sliding it-in with it powered. something around the AC line underneith

Right, in but not on. I was just thinking if the Audio Trans went bad then I wouldnt hear ANYTHING out of the speaker right or wrong?

Check to see any components that hang the lowest under the chassis. Maybe just hit something ,one side of a cap disconnected. Make sure outlet is still hot

Look around the rectifier tube for a burnt or cracked resistor in series with the cathode. If you see nothing, take some voltage readings in the power supply.

I looked at it quick and didnt see anything but like i said it was just a quick glance. I'll check further when I get home tonight. I looked for the schematic at nostalgia air, they have 3 w117's listed but none of them have the tube lineup in mine. I have 25z6, 25L6, 25L6, 6SC7, 6SQ7, 6SK7, 6SA7, 6SK7 does anyone have or know where I can find the correct schematic?
Joe

I found the schematic at radiomuseum.org where I am a memeber but I cant get it to enlarge the schematic for printing. If anyone is a member there and can help me out getting the schematic, here is the link:
http://www.radiomuseum.org/r/minerva_w117_1.html
Joe

could be that B+ got wacked or something is touching grounding the signal somewhere or both

Here's the schematic from NostalgiaAir.

http://www.nostalgiaair.org/PagesByMode ... 010877.pdf

Joe: put to rest your idea about the audio transformer, which the problem probably isn't. With the radio unplugged, put your ohmmeter leads one on each of the 50L6 tube plates, pin 3. Should hear a crackle from the speaker if xfrmr and spk are ok.

Edit: I spoke too soon: see you have a different tube line up. Even so, testing as above on plates of output tubes will work the same.

OK I put the leads from my ohm meter onto pin #3 the pos lead to one pin the neg to the other (on the 25L6 Tubes) and with the radio off I got a static crackling noise out of the speaker. So this means the xformer is good? I am assuming the 25L6 tubes are the output tubes since these are in the place of the 50L6 tubes in the other schematic. where do I go next/ I see no obvious damage to anything like a burnt out resistor or anything like that. One thing I did notice is that the static I am getting through the speaker is uninterupted by turning the tunning knob. In otherwords as I turn the tuning knob to search for stations nothing happens. the static stays the same and no stations are picked up even faintly. Dont no if that makes a difference but thought I would mention it.
Joe
Joe

print out the schematic. time to do some circuit tracing. no signal for sure. trace each section beginning with the input signal path. wouldnt hurt to check B+ with DC volt meter. I would check it at each plate and screen since you had a 'spark'. stuff cant be touching under the chassis

Output transformer and speaker are most likely OK per your test. Echoing TubeAmp's post to do some tests. Do all the tubes light? If so, set your voltmeter for at least 200 volts DC. Put the negative lead on the negative side of the electrolytics and probe plates and screens of all tubes. You should have something between 60 and 100 volts on most tubes and over 100 on the output tubes. If not, investigate the path from the rectifier and why it's not getting there. Should be full voltage on the screens of the output tubes which indicates the rectifier is doing its job: notice the screens are connected directly to the output of the B+ filter.

If you have good voltages as above, leave the negative lead of your voltmeter disconnected and touch the other lead to the grid, pin 2, of the 6SQ7. Should get a loud hum through the speaker indicating the audio stages are OK and the problem lies in the IF or RF stages.

OK I checked the 2nd pin of the 6SQ7 and got the loud hum from the speaker so i'm assuming the trouble is in the IF or RF. As far as checking the voltage I get really nervous that I'm going to check the wrong pin and with the neg probe on the chassis I would blow something up! Is there an easy way to determine wich pins are plate or cthode etc? Like I said I get nervous still with high voltage. Thasnks so much for all the help with this. Its a long story but I really want to get this figured out.
Joe

Somewhat OT, but you might be running the tubes a bit hot using 25L6's instead of 50L6's. Unless you've already increased the series string resistor value to compensate.

This is a different radio then the one in the schematic in that it came with the 25L6's. I have the original schematic and it shows the 25's in those spots. I just found it tonight, I knew I had it here somewhere. It is the one that came with this radio.

What I am trying to figure out is how do I determine what pin is plate what one is cathode etc? Ilike I mentioned I still get spooked by hi voltage a little and I want to make sure im hitting the right pins before I blow something up! LOL but its really not funny, you could get hit pretty hard by this stuff (high voltage) and I want to make sure i'm doing it right,
Thanks,
Joe

The Nostalgia Air schematics have the pin numbers indicated, although they're just barely legible. Power the radio through an isolation transformer, that way you are at least protected from accidental contact with the house line voltage. And I like to use a bit of shrink-wrap tubing around probe tips, leaving only a millimeter of bare metal at the end to make contact with. Makes me feel better navigating the probe through other wiring.

you should get familiar with tube data http://tdsl.duncanamps.com/tubesearch.php
enter the tube type in the window.
you should understand tube pin-out. you should be familiar with electrical circuits knowing safety precautions while working with high voltages. you should be familiar with your meter. you should be comfortable enough without being fearful. caution and fear are not the same thing. if you are not sure you should not be poking around a chassis. let someone knowledgeable work on it for you or acquire some knowledge yourself before poking around blindly

Joe,
"then I wouldnt hear ANYTHING out of the speaker right or wrong?"

Sure if it's bad, but many other things can cause this problem. I'm with tubeamp, you need to pickup on a few basic things working on these old radios. I must say and have been saying it for years and believe me it was taught in the late 40's and to this day...at a certain point (age of radio) fixing them is more mechanical than electronically. BUT when it comes to problems, you need a reasonable understanding of the components, schematics, etc. to troubleshoot. I don't want to imply you can't understand radio electronics but your posts to me indicate you don't take a systematic way. You somehow want to cross the finish line by jumping from a bush rather than run the race. You need to fall back and regroup. I'm sorry if this doesn't set too well with you. And one thing about AC, if you short it can leave an indication, a weld looking burn spot. Since your set is a filament series string you could have an open somewhere. I would look there, path of least resistance.

Bill J.

P.S. If posting is too harsh, kill it. I won't care or will be upset. And won't respond to negative BS. Sometimes you got to lay it on the line.

I'm not upset at all about it. It's why I came to this site over a year and a half ago. ive fixed many radios in that time and I am REALLY careful around electricity. This was an idiot mistake that started this whole thread and now I am trying to learn so it doesnt happen again. I need to learn two major things , how to read a schematic better then I do now (which I am trying to learn now) and how to tell what pins are what on a tube. I know how tubes are numbered and I see the numbers on schematics I just need to learn how to tell what pin is what. Like what pin is plate, cath, screen etc. I dont know how you tell which number shown on the schematic equals plate or cathiode. thanks everyone for the help, I honestly appreciate it.
Joe

Also does someone want to explain tube pin-out to me/ Maybe that will help with what I am trying to learn, which is what pin is what on the tube. How do I tell which pin is for the plate, the cathode etc.
Thanks
joe