I (stupidly) agreed to take on a tube powered F-1600 for a local record shop and this thing is kicking my butt up one side and down the other! Firstly, It seems as if the cabinet is screwed and glued together, accessing the internals without damaging the cabinet has proven futile. All 4 tubes and idler wheel have been replaced. I put the rectifier in, let it warm up, and still no sound. So I turned it off and heard - then saw that the transformer was leaking tar. I'm at a serious loss, and would appreciate ANY help that might be out there. Thanks.
Dave
Drynamic13,
You don't mention anything about your knowledge of electronics in general, and tube (I.e. high voltage) electronics in particular. I will assume you are a beginner.
Many beginners assume that the first place to start is to replace the tubes, yet tubes are comparatively reliable. I recommend you start by reading here:
http://www.antiqueradio.org/begin.htm
The problem is most likely that one or more of the capacitors in the set have deteriorated and are now effectively short circuits. This is probably why the transformer heated up to the point of melting some of the internal tar. Do not power up the set again until you have at least replaced the electrolytic capacitors in the power supply.
Plenty of other sources of information on the web. Google is your friend as you start to learn. Read up and ask lots of questions.
Jon
P.S.
In the link above, be sure to read sections titled "First steps in restoration", as well as "Replacing capacitors in old radios and TVs".
Jon
1. First the bad news:
Plugging it in is not the place to start.
Back in the days when this technology was current indeed often times a fault could be traced to a weak tube, but after 60-70 years it is bad wiring, bad capacitors, open coils and such.
Plugging the radio is the LAST thing to do when you are through with the chassis, having changed all capacitors that are not micas (about 10 on average counting two electrolytics), having replaced all out of spec resistors, mended all bad wiring, supplied new power cord, and performed a general cleaning overall. And then test the tubes and put the good ones back in (youcould get away with weak tubes as long as they are not gassy or shorted).
It is more work that you have possibly thought, so if you are not up to it, pull out of this project before you putt too much effort to quit. If you are up to it, we will at least help you with advice on what to do and troubleshooting should that become necessary (sometimes it is not).
2. Now the good news: your device is from 1958, this means the capacitors other than electrolytics might not need yanking and could stay. So if you are lucky the electrolytics will be it. If not (you said the transformer leaked tar) the transformer might overheat due to bad caps / bad rectifier (could be a selenium type those years) but might still survive.
3. Neutral news. Unless you are doing it out of friendship to the store owner, do not expect to make money on this project. At best you will get paid for parts, and even if you are paid for your time, you will spend way more time and effort that you will get compensated for such that you will consider it worth it.
So think it out well before you plunge.
Thanks for al the help and advice so far guys; I'm going to get cracking on this today.
PAradiogeek: I was an electronics service technicians in the military, but I am a beginner with gear of this age and type. It was originally brought to me for an idler wheel repair and replacing a plug that was quite unsafe. It was upon doing that new problems began to appear (such as blowing out the rectifier and the leaking transformer.). I have been trying to find the necessary information to continue on with the repair and have already attained more form this thread than my previous research, and I would like to believe I'm pretty capable at internet research.
Morzh: You're correct about the labor of love. I am doing this to cover the cost of parts. I got out of the electronics repair business because and do it more as a hobby these days.
Klondike98: Thanks for the links! I'm hoping I can can this project back on the rails and OUT OF MY HOUSE! Haha!
Once you get the sch,
(you are an electronics tech so I won't lecture you on basic safety, bad wires etc - just mind the high voltage, tubes get it very high)
1. Whatever rectifier you got, disconnect it.
Then plug the transformer in and watch if it is still heating up or stays cool.
Measure its voltages to at least be in the ballpark (the one to the rectifier - maybe 200V or something of the sort, filaments are probably 6.3V for the miniatures).
If it passes that, deal with the rectifier. If it is Selenium type, you will probably replace it with a diode bridge (you could use 1N4007 for this) and a resistor if needed.
2. if you are OK, start looking for a reason the transformer heated.
Inspect the wiring, look for load shorts from the rectifier.
If not obvious, go to recap.
3. I would not touch any caps other than the electrolytic ones. If they dried up, and you are not keen on restuffing them to keep the looks, simply cut them off (do not bypass), remove and replace with a modern type. If you want to keep some looks, leave them in fully cut off, still use the newer types instead. if you are more of a perfectionist, remove them, gut them, re-stuff with the modern type, seal back, solder in. In the rectifier section, especially for the one that is the first to filter the rectifier, Use good grade caps with as high a ripple current as possible. If needs be, you could parallel or serialize.
4. Test the tubes.
5. Put them in, connect the speaker.
6. Plug in, watch the transformer. if it is still not oozing the tar, proceed. if it is, well then we will deal with it. If possible.
Agree, sounds like the solid state rectifier is bad.