I have a Zenith Transoceanic Model 8GOO5 which I bought not working. I tested all the tubes and all tested good however, the 117Z3 rectifier tube was not on any of my tube charts for either my Mercury 1100 or my Precision 10-12 tester. I bought a replacement 117Z3 and tried the radio and it worked. However, after an hour or so, the radio quit working.

Hi Paul

Bad electrolytic filter caps can damage the 117Z3 tube. The caps can draw excessive current, heat and blow the cathode connection in the tube.

Can your tube tester test any 117 volt tubes? The 117Z3 is a rectifier with plate on pin #5 and cathode on pin #6. Pin #6 should have around 120 volts DC if the tube is ok.

Norm

: I have a Zenith Transoceanic Model 8GOO5 which I bought not working. I tested all the tubes and all tested good however, the 117Z3 rectifier tube was not on any of my tube charts for either my Mercury 1100 or my Precision 10-12 tester. I bought a replacement 117Z3 and tried the radio and it worked. However, after an hour or so, the radio quit working.

: Hi Paul

: Bad electrolytic filter caps can damage the 117Z3 tube. The caps can draw excessive current, heat and blow the cathode connection in the tube.

: Can your tube tester test any 117 volt tubes? The 117Z3 is a rectifier with plate on pin #5 and cathode on pin #6. Pin #6 should have around 120 volts DC if the tube is ok.

: Norm

:
: : I have a Zenith Transoceanic Model 8GOO5 which I bought not working. I tested all the tubes and all tested good however, the 117Z3 rectifier tube was not on any of my tube charts for either my Mercury 1100 or my Precision 10-12 tester. I bought a replacement 117Z3 and tried the radio and it worked. However, after an hour or so, the radio quit working.

Norm,
Thanks for the reply. In answer to your question, I don't think either of my testers are capable of testing the 117V tubes or at least I have no tube chart that has any listing starting with "117". I do have a cheapo "Fedro" tester that has just a neon light to signify whether or not there is an open in the tube and that tester says the tube is OK. As for the voltage that you mention, I will try to measure them, but the tube does not even light anymore so I don't know if it is possible.
I think that you are right that it is a problem with the capacitor(s), but I have never attempted recapping a set as of yet.
I have a copy of David Johnson's Book which makes it seem like not such a big deal to recap using caps of equal or greater value than those being replaced. However, I have read other articles which make it sound somewhat trickier. I am not afraid to try but I would like a little expert advice before recapping.
Thanks,
Paul

Paul

Your tube filament is most likely open. A 117Z3 can be replaced with a 1N4004 silicon diode and resistor in series. The band end of the diode connects to pin #6 of the 117Z3. The other end pin #5 through a resistor. 47 ohms, 1 or 2 watts, should be ok. I would go this way until the radio works. The diode is much lower cost than another tube.

Some tube testers can not supply the 117 volts required by this tube. You don't need a tester when a tube doesn't light.

Changing electrolytic filter caps isn't hard. Look up the schematic and buy replacement caps with slightly higher capacity and the same or greater voltage rating. The originals are usually a group of caps in a single unit. They can be replaced by individual caps. You do need to watch polarity. One lead will be positive, the other negative. Post here when you have questions.

Use a variac when powering up the radio. If you don't have one, wire a 40-60 watt light bulb in series with the radio. The light will act somewhat as a fuse.

Norm

: Norm,
: Thanks for the reply. In answer to your question, I don't think either of my testers are capable of testing the 117V tubes or at least I have no tube chart that has any listing starting with "117". I do have a cheapo "Fedro" tester that has just a neon light to signify whether or not there is an open in the tube and that tester says the tube is OK. As for the voltage that you mention, I will try to measure them, but the tube does not even light anymore so I don't know if it is possible.
: I think that you are right that it is a problem with the capacitor(s), but I have never attempted recapping a set as of yet.
: I have a copy of David Johnson's Book which makes it seem like not such a big deal to recap using caps of equal or greater value than those being replaced. However, I have read other articles which make it sound somewhat trickier. I am not afraid to try but I would like a little expert advice before recapping.
: Thanks,
: Paul

Paul, i just finished an L-600 which is different from yours but if the circuitry layout is somewhat the same, The neg end of the new filter caps connect to the B- line, which is not the same as chassis..
Unless you want to hide the new caps in the old can (Of which there are 4, you'll be pressed for space) go ahead and note the lug symbols and match them to those values on the can...Just cut the wires one by one, connect them to the plus ends and tie off the NEG to the can mount lugs (all 3 should be continious) But NOT the chassis...Do one at a time, then move to the next but plan ahead how you plan to lay the caps in because there isnt much depth space to the chassis.
You'll be working in a tight space.. A transoceanic isnt really that easy to work on.. make sure you havent moved any components up against each other before you're ready to fire up... be very careful not to put your hands into the fine wires around the band selector tower...
Follow norm's advice about the light bulb...Transoceanics tend to blow tubes really quick if anything's wrong..
dave

Norm,
: Thanks for the reply. In answer to your question, I don't think either of my testers are capable of testing the 117V tubes or at least I have no tube chart that has any listing starting with "117". I do have a cheapo "Fedro" tester that has just a neon light to signify whether or not there is an open in the tube and that tester says the tube is OK. As for the voltage that you mention, I will try to measure them, but the tube does not even light anymore so I don't know if it is possible.
: I think that you are right that it is a problem with the capacitor(s), but I have never attempted recapping a set as of yet.
: I have a copy of David Johnson's Book which makes it seem like not such a big deal to recap using caps of equal or greater value than those being replaced. However, I have read other articles which make it sound somewhat trickier. I am not afraid to try but I would like a little expert advice before recapping.
: Thanks,
: Paul