1956 Cadillac Fuse Question

[J. Gomez]

Make sure it is the FAT metal canister looking piece you try to remove; if it is the right item, you will be able to rock it back and forth in its connector if you try moving it gently.

I post this warning because there is a multi-section, vertical mount capacitor nearby that is also in a metal canister looking item (if it has not been replaced) - This will be THIN compared to the vibrator and this will be solid if you try to move it gently but you can damage things if you try to force this one to the side trying to get it out.

Dan,

Good point..!   

And since the vibrator will be very hard to remove (if it never got serviced) it could easily be mistaken by the silver can capacitor(s) if one is not familiar with these.

As Bruce mention above the vibrator would be next to the 0Z4 metal tube.

[Lexi]

Found this interesting link on an old radios site. Discussed is a vibrator in a '56 GM radio and also its removal and notes on retro fitting with an electronic replacement. A lot of this is intended for those who repair radios, and is above my pay grade. Jose & Dan will certainly be able to relate to it. The poster was assisting his son with his restoration of a 1956 Cadillac in which he was rebuilding the radio for that car. Clay/Lexi

https://www.antiqueradios.com/forums/viewtopic.php?f=6&t=355821

[J. Gomez]

Found this interesting link on an old radios site. Discussed is a vibrator in a '56 GM radio and also its removal and notes on retro fitting with an electronic replacement. A lot of this is intended for those who repair radios, and is above my pay grade. Jose & Dan will certainly be able to relate to it. The poster was assisting his son with his restoration of a 1956 Cadillac in which he was rebuilding the radio for that car. Clay/Lexi

https://www.antiqueradios.com/forums/viewtopic.php?f=6&t=355821

Clay,

Thanks for posting the link, yes I do follow the same forum from time to time and do remember this particular post. I can only speculate from the multiple posts that the SS vibrator he used was one available as replacement back then and maybe the same one available now as well.   

The issue he was experiencing and the pictures he posted to me indicates the SS and the old type behave differently but there is no mentioning on which type SS he used for the testing.

I try to minimize on specific details as these issues normally are not related to Cadillac per-say. I've used a different approached when I made the SS ones to closely mimicking the old electro/mechanical type.

[Lexi]

Yes, there are always pertinent details missing.  Being one of the "Cadillac Gods" I am not surprised that you were aware of that post Jose. Seems that our Cadillac guy is not overly familiar (if at all) with these kinds of builds. Neither am I at 100% on them for that matter either. But if he has to have a professional look at it at least he may be able to better communicate with the service tech based on all this input. Too bad that when we are in those situations that you are not there, whispering in our ear, to get the most out of such a visit! Clay/Lexi

[gatech1956]

So just a quick update the vibrator was replaced with a solid state one. The radio stayed on longer but then the fuse blew. However, the 0z4 tube was out during the installation of the new vibrator and looks like when I put it back it turns out the middle prong had broken off. So by the end of the week I will have a new tube and then I can retest

[bcroe]

Interesting notes about the dead time of electronic substitute
vibrators.  There must be some interval for a mechanical vibrator
to physically change contact position, but it is not adventagous to
the process.  Electronic inverters may reduce dead time to near
zero. 

It appears that in an effort to add dead time, the vib sub deliberately
had the dead time the same as the active on time, probably counting
at twice the frequency.  That is going to force all the B+ power to be
transferred on a shorter, higher power duty cycle.  That means lower
efficiency, probably hotter components, maybe shorter life. 

Here, leaving out the 0Z4 should reduce the load, less likely to blow
a fuse than when present.  I would go farther and try without the
vib, does that blow a fuse?  If so I would suspect a bad transformer. 
If fuses blow with the vib out, the radio needs to come out, filter caps
and other things connected to the 12V supply are suspect.  Bruce Roe

[gatech1956]

Well I do have a redi rad hooked up to the radio but it's never given me problems. The radio has worked flawlessly ever since I got the car 6 years ago. It just decided to start blowing fuses alll of a sudden

[J. Gomez]

So just a quick update the vibrator was replaced with a solid state one. The radio stayed on longer but then the fuse blew. However, the 0z4 tube was out during the installation of the new vibrator and looks like when I put it back it turns out the middle prong had broken off. So by the end of the week I will have a new tube and then I can retest

D. Steeves,

hmm if you blow the fuse with the rectifier tube 0Z4 out and with the vibrator inserted this indicates there may be something shorting the +12V source at either end of the power transformer.

It is highly recommended to replace the "buffer, filter and hash capacitors" around this area if the vibrator is replace in addition of replacing the rest of the old paper wax capacitors.

Removing the rectifier tube just disable the B+ (DC high voltage) but the vibrator will still be functioning and the output transformer will still have the output AC voltage across the output.

Good luck..!

[J. Gomez]

Interesting notes about the dead time of electronic substitute
vibrators.  There must be some interval for a mechanical vibrator
to physically change contact position, but it is not adventagous to
the process.  Electronic inverters may reduce dead time to near
zero. 

Bruce,

The use of transistors to drive the SS vibrator will make them more of an "on/off" format and thus I've used MOSFETS instead. 

Here was my reply on this topic.
https://forums.cadillaclasalleclub.org/index.php?topic=159006.msg482116#msg482116 

The old style vibrator generates a very close square wave pulse, "however" there is a small difference ("t" constant) when the contact opens and the pulse drops from max to "zero" and reverses to the negative side this makes about 65% closure, this is why the wave is not a perfect square wave.

But since this is outside the scope of this forum/topic "Cadillac" you can do a search for "Vibrator theory" on-line.

[dn010]

If you look inside the radio, you will probably find many of the paper capacitors have the ends bulging off of them. The multisection capacitor is highly likely to be bad as well. I removed and tested one three days ago to find what should be 20uf was almost 98 (!) and the other two sections were in the 60s. I don't think this would cause a blown fuse but it is harsh on the rest of the components to be operating like this. The 0z4 can be opened up, glass tube removed and a few 1n4007 diodes soldered in it's place, it is then cool to the touch while operating and will outlast a glass tube.

Working on this radios is not for the faint of heart, I've been "bitten" a few times inadvertently touching the wrong things while powered up, so for most people, a specialist is in order.

[gatech1956]

Also, the 7 1/2 amp fuse for the radio...does it need to be the short one or will the long ones do? I have seen both at hardware and auto stores

[J. Gomez]

Also, the 7 1/2 amp fuse for the radio...does it need to be the short one or will the long ones do? I have seen both at hardware and auto stores

The size of the fuse (short or long) is dictated by the fuse holder size, if you have the correct fuse holder in place a SFE 7.5A or a 7AG (AGW) size at 7.5A should do it these are 7/8" in length.

Good luck..!

[gatech1956]

So good news is that the fuse isn't blowing anymore after replacing the vibrator with a solid state one and replacing the 0z4 tube. The bad news is the pilot light comes on but no buzz or noise. I checked under the speaker and the two tubes were glowing. I even poked them with the eraser of pencil like the shop manual says and there was not a cracking noise. What else should I do?

[J. Gomez]

So good news is that the fuse isn't blowing anymore after replacing the vibrator with a solid state one and replacing the 0z4 tube. The bad news is the pilot light comes on but no buzz or noise. I checked under the speaker and the two tubes were glowing. I even poked them with the eraser of pencil like the shop manual says and there was not a cracking noise. What else should I do?

Well the bad news "it's time for a major repair"  , the vacuum tubes filament/heaters are glowing in the amp and radio that tells your there is 12V going to them, the other is the B+ high voltage for the rest of the unit.   

[bcroe]

There is a chance the vibrator is not running, hard to tell
with solid state.  You could let the radio warm up with
vibrator and 0Z4 in place, then use a DC clamp on ammeter
to observe 12V drain. current  If pulling the vibrator does
not reduce the drain, the vibrator is dead. 
good luck, Bruce Roe

[gatech1956]

I ended up taking out my radio and sending it Howard Foulds of HF Enterprises. He really knows his stuff. The root cause was the capacitors in the power supply, but obviously everything could have used some refurbishment. He even replaced the speaker with a new old stock one as mine had dried out. If you need help with radio I would recommend him.

Here is what was done:

ALL electrolytic capacitors replaced with NEW.
Several line noise filter capacitors replaced with NEW.
Several key resistors also replaced with NEW.
ALL wax dipped paper / foil capacitors replaced with NEW.
ALL the tubes removed & tested .
ALL controls flushed out & lubricated.
New pilot lamp installed.
Tuner circuits electronically re-aligned.
Pushbutton pre-sets circuit board & electrical contacts removed & cleaned.
Wonder Bar relay & switch contacts cleaned and adjusted.
Clean, lubricate & adjust the mechanical tuner & pushbutton mechanism.

[bcroe]

Sounds like a good job, of doing everything an old
radio needed to be done.  Bruce Roe

[Saturnin15]

No more fuses blowing! 😜😂😂😂

[35-709]

   That'll fix it!  Keep the fire extinguisher and battery cable cutters close by.

[The Tassie Devil(le)]

I suppose that is where the saying, "A bolt from the Blue" comes from.

Bruce.