[Jeepeto]

Little better now after cleaning

[Jeepeto]

Order side

[Jeepeto]

The cone to be replaced, I will try to save the coil

[EdHolland]

Hi Jeepeto,

Please see my 16X Story thread - it may give you some ideas on speaker cone making. I did exactly what you plan - save the coil - and made a new cone and surround. It works really well.

Cheers and good luck,

Ed

[Jeepeto]

Thanks Ed, I will take a look this is my first speaker re-cone, I am getting out of things to do waiting for parts, including new cones
Cheers

[EdHolland]

You are welcome Jeepeto,

Here is a link to the relevant page of my restoration thread:

http://philcoradio.com/phorum/showthread...572&page=2

Cheers

Ed

[Jeepeto]

Really good Job Ed! Maybe I will do a try to do a cone from some of my kid's thin cardboard for homeworks in the waiting for the replacements, they look very similar to the old paper and have same thickness, by the way beautiful restoration of your 16x, those big forniture radio are very rare in my country from that age...

[EdHolland]

Thank you Sir I would recommend experimenting first, to get the geometry right. Then you can make an accurate template. It is also a good idea to set up a jig to position and hold the voicecoil accurately whilst gluing it to the new cone.

Cheers

Ed

[Jeepeto]

I have got the grommets for the tunning unit and installed it, I decided to put power on the radio without the speaker with a variac and a amp meter to check any short or smoke, the power line have a fuse, I had no 115 volt 1amp fuse so I used a 220 @ 500mV, no tubes, after rissing slow the voltage the bulb at 30vac starts to glow, nothing seems to be bad...0,01 amp.After I install the rectifier only, 0,02 amp with 30v, 65vac and the ampmeter starts to rise slowy but steady, I touch the tube with gloves and can feel is really hot, the bad thing is that the amps went up more than 1 amp and blew the fuse....I replaced it and started again with 50vac this time (only 5Y4gt) the amps went to 0,6 and keep in there, I tried to check voltages underneath the chassis and tube sockets and I got only 3vac of the heater pins, nothing in caps, switch off, remove the 5Y and Test the rectifier socket, I got (with 30-40vac) the 5,5vac and 112vac....I am getting puzzled since the transformer was checked before and looked ok...all wires put in old places, surely I am doing something wrong since is my first tube radio but could be other thing?
Cheers

[Electrothaumaturgist]

I would think that you would want the speaker plugged into the circuit when that rectifier tube is installed... I always make sure of that. I think it matters, as you're putting a load on the unit. Maybe.

[Jeepeto]

I will try to install the speaker with the prototype cardboard cone to Test again all, in case it still blow the fuse, could be the rectifier tube? I though if is hot is working, but without it the fuse is intact...

[Radioroslyn]

So here the deal. W/o the speaker connected the power supply no load (all this HV w/nowhere to go) #56 keeps charging up and charging and charging till it get to it maximum voltage rating @ 450v. It's still charging up and up. After that happens it shorts from being exposed to too much voltage. This in turn put a terrific load on the rectifier tube (80 tube) and it shorts. With the 80 shorted it takes out the HV winding on the power transformer.

To find out what is going on w/your set unplug from the ac line, remove all tubes, and lamps. Used the schematic to make sure that the resistances on the transformer windings match the schematic and what there are supposed to be connected to. You may have something miss wired from rewiring the transformer.
If all that checks OK then replace all of the tubes and lamps EXCEPT for the 80 leave it out. Power it up and measure the ac voltage across the two small pins (2 and 3) of the 80 socket. If all is well should see about 600-700vac.

If that checks OK then replace #56 put the 80 tube into it's socket and connect your dc voltmeter + to the + side of #56 and the - to the chassis. Should see about 250vdc.

GL
One angry 80 tube !!!!!! Pic stolen from the net.

[Jeepeto]

Thanks for your explanation Terry, still learning and maybe this time in the bad way for not connecting the speaker hope I have not burned anything, the 80 tube did not shine like the photo O_o just got hot...and never applied more than 60vac 1amp, for next times always is needed to have all tubes and speaker just for Test shorts or other things? Any recommended book for learning testing tube equipment?

[morzh]

1A at 60VDC is too much.

Anyway, do what Terry said, and before putting the 80 back measure in the 80's socket between either of the filament (fat) pins and the chassis. You should see large resistance, certainly no less than tens of kOhms. In other words, we are looking for the load short. Then proceed replacing the 80 tube.

[Jeepeto]

Thanks a lot for the help and advices, my skills in this is basic, and any help is much apreciated, after work I will try to check all and will cross my fingers... If the transformer HV is dead are easy to repair/find?
Cheers