11-17-2011, 08:17 PM
My meter readings jump all over when I take a reading. Should it stay at a number or should it bounce around a lot?
Bad Transformer?
11-17-2011, 08:17 PM
My meter readings jump all over when I take a reading. Should it stay at a number or should it bounce around a lot?
11-17-2011, 10:44 PM
Should stay pretty steady. Think it's time for a new transformer. Sounds like you have win dings that are shorting internally.
Terry When my pals were reading comic books I was down in the basement in my dad's workshop. Perusing his Sam's Photofoacts Vol 1-50 admiring the old set and trying to figure out what all those squiggly meant. Circa 1966 Now I think I've got! Terry
11-18-2011, 09:33 AM
I found out you need to not have the power turned on when taking ohm readings, the numbers don't jump as much and i'm getting the correct readings.
So my readings from pin3 to pin 2 is 265ohms. From pin 2 to negative lead of part 61 is 128ohms. From pin3 to negative lead of part 61 is 138ohms. That's 266 ohms together and that's what pin2 to pin3 measure. That's good I think. My reading from part 64 the ac line conditioners to the on\off switch is around 3ohms, the specs call for 7omes. Not sure what to think there. I'm probably going to need a new transformer, but I wanted to know for sure and figure that out by the multimeter telling me that there's a problem.
11-18-2011, 03:04 PM
Good news!
I went for broke and put in my new 84 tube and cut it on. All the tube lit up and the transformer stayed cool as a cucumber!! I even got static out of the speaker!! I've not heard anything from this thing till now. I didn't have the antennas attached so I guess that's why I didn't hear anything but static. My static got more bass as I turned the bass knob and also got louder and quieter when I turned the volume knob. So i think everything is coming together and I believe the transformer is still good. Now i'm going to do some more cleaning to the chassis and check all my connections and attach the antennas. Anyone have good suggestions on what they'd do next? -Dark
11-18-2011, 09:24 PM
Congrats,
I hope as someone here said, you just boiled some wax and did not fry the enamel on the wires. It takes one single turn out of many thousands to short and this is it. So far looks good, but keep an eye on it. For the future: Personally, I, when turning on the device the first time, did this: 1) I plugged a huge 30W or 40W 700 Ohms (or close ) resistor IN SERIES with the 110V plug, and only then plugged it into the 110V outlet. Then I connected my meter set on VOLTS to the output (any, as long as you know approximately the Voltage reading that it should produce) and turned the switch ON, being ready to turn it OFF immediately if needed. I was looking at the Plate voltage winding and so the expected reading was in at least couple of hundred volts. Also, I took out ALL tubes, in case there is a problem with them. Once seeing the plausible voltage, I then removed the resistor and plugged the receiver directly into the 110V. Then, and only then I started putting in tubes. PS. It is possible to use a table lamp with the incandescent bulb (ONLY incandescent), or just a light bulb with the socket in series instead of that resistor. 2) NEVER EVER measure your OHMS in powered-up device. You stand to burn your Ohm-meter, and as the best outcome, your Ohms will not be correct. Ohmmeter relies on producing a current in the measured circuit by applying its own voltage, and the measuring the V/I=R. If the circuit is powered, it measure God knows what current, induced by God knows what voltage, and at the same time possibly being subjected to voltages much higher than it can take and stay un-destroyed. People who do not drink, do not smoke, do not eat red meat will one day feel really stupid lying there and dying from nothing.
11-21-2011, 12:14 PM
I'm now moving on to my next set of issues since it appears that my transformer is good. I have sound out of my speakers, but as I turned the dial, I don't get any stations. I guess there are a couple of things to test.
I'll keep updating this thread with my results unless anyone thinks I need to make another thread pertaining to my reception issues. I'm going to test my oscillator coil and see if there are any problems there. I've been using this step by step guide to help me make good measurements on my radio. It's from another forum, but it's a great guide even if it's not your radio in the guide. It helps newbies read the schematics and find what it references to the actual wiring. http://www.antiqueradios.com/forums/view...p?t=152169 Please post if you all have any receptions tips you might have for my 40-180 radio. Thanks to all that have posted, I couldn't have done it without you all. -Jeff
11-21-2011, 01:03 PM
If you think there is a problem with the osc I'd just take a listen for the osc signal in another receiver. The earlier Philcos from like 1931-35 or so are ones that have the rotting wire on the coil issues. I would be a little surprised if your set has that problem.
Terry When my pals were reading comic books I was down in the basement in my dad's workshop. Perusing his Sam's Photofoacts Vol 1-50 admiring the old set and trying to figure out what all those squiggly meant. Circa 1966 Now I think I've got! Terry
11-22-2011, 12:33 AM
Yikes, let's take a step back here and make sure you understand how to properly and SAFELY use your tools before you do any more poking around in a tube circuit. You're dealing with voltages substantially higher than what comes out of the wall and if you aren't careful you can easily destroy your test equipment, your radio or worse! Not trying to come off as rude or anything, but this stuff really can kill you.
There are very few measurements of any sort that need to be taken with the equipment powered up. Get in the habit of unplugging it and discharge the electrolytic capacitors before you start poking around.
11-22-2011, 09:53 AM
Ok, what I've done now is to use contact cleaner on my band selector and the push buttons and I turned it back on and walla, I'm able to hear a station on the AM!!!! I couldn't tune in anything on the police band, but did get something on the SW. It works, i'm kinda surprised that i'd get anything out of it. Very cool!!
Now that I have a station coming through, I tuned it in and I hear what it sounds like wind blowing. The kind you'd hear from an old movie. Any ideas on that? I'm still going through the radio and checking all my circuits and learning a lot as I go. There were a lot of things I didn't know when taking measurements. Ohm readings with the power off sure helped. I have a question on taking ohm readings from different parts. Should I get a reading if I put my test probes on either side of a capacitor or resister? Does it matter if it's wired in or not? If I had a loose one and I connected the leads, should I get a reading? Sometimes I don't get a reading when I put the probes on either side of the posts that a capacitor is connected to. I have several places in the radio where this happens, I'm not sure what to think. Could there be too much solder on the posts? Could the part be dead? If it's dead, how many dead parts can you have and still tune in stations? Thanks for everyone's help so far! -Jeff
11-22-2011, 03:47 PM
OK, sounds like you are almost there. You will hear little or nothing on the police band, as it is not presently in use for communications. If you have replaced all the paper and electrolytic capacitors, and any resistors out of range, and made sure the antenna coil is still patent, and voltages are about right, it is time for an alignment.
11-22-2011, 11:28 PM
Congrats!!!
Some many questions!!!! general rule is when measuring resistors in circuit. Set should be off. If it has something in parallel you will need to disconnect one end of the resistor that is being tested. An ohm meter doesn't really test capacitors, except for leakage. When testing coils usually the coil is such a low resistance that the capacitor in parallel doesn't change the resistance so those can be done it circuit without disconnecting. Too much solder can be a problem if it is causing a short to an adjacent terminal or to the chassis. So I've got a question for you. Why does it matter if there is a cap across a resistor, why does it not read the correct resistance?? Terry When my pals were reading comic books I was down in the basement in my dad's workshop. Perusing his Sam's Photofoacts Vol 1-50 admiring the old set and trying to figure out what all those squiggly meant. Circa 1966 Now I think I've got! Terry
11-23-2011, 09:41 PM
I can understand the newbies here wanting to get their old radios working asap, but when I check in here seeing newbies that don't know how to use test equipment, or have the necessary test equip that is required in this hobby, or have any basic idea how to properly check for voltages,resistances, or how to check caps, or transformers the proper way with proper knowledge and test equipment really scares the he** out of this oldtimer!!
Prodding around in and under old tube type Radio chassis' can KILL YOU !!!!!!!!!!!!!! Don't get in a hurry trying to educate yourselves flyin' by the seat of your pants messin' around with high voltages!! Slow down, ask questions, and realize that you don't really need to accidentally Kill yourselves messin' around in the "no messin' around zones" under all these old radio chassis'! It sometimes takes years to accumulate the knowledge and all the proper test equipment to properly restore these old sets!! When experimenting, by all means, keep the sets unplugged and all electrolytic capacitors carefully discharged from - to + ( in that order) with a insulated jumper wire before making any circuit changes or testing components! Go Slow, pay attention, Ask Questions, Take your time, and you will still be here with all us to learn much more in the future! No disrespect intended towards the newbies at all !!
11-25-2011, 02:20 AM
I use an ordinary 100W incandescent lightbulb in series with a set the first time I power it up. If the bulb glows brightly and stays bright, something is wrong. If it starts out bright and then dims down, things are looking good.
When it comes to testing components in circuit, you really need to have the schematic in front of you to see if any other parts are wired in parallel that could throw off your measurement. A resistor checked in circuit should never read higher than the rated value, but it may read lower if it has something in parallel. As for transformers, my experience has been that they almost never fail on their own. It's almost always a short somewhere else that burns them out. There is some good general information about transformers and winding here: http://ludens.cl/Electron/trafos/trafos.html
11-28-2011, 12:00 PM
So I haven't posted any pictures and I feel bad, everyone likes to see what there giving advice on. Here are a couple. These are all before I started work on it.
11-28-2011, 12:01 PM
One more.
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