1956 Zenith Hairpin Leg Consolette HFY-17E

[Hi-Fi-Mogul]

Yes Greg,
That phono plug diagram you addressed is very helpful.

My next task was to determine where I could wire an
AC jumper to power up the amp when I have it
re-capped.
Thanks for that answer.

I still get confused at times with these units that have an AC
leg tied to the record changer motor/switch.

In 1958, Zenith used an On/Off switch
on the volume control.
That is shown on the insert on the Beitmans
schematic.

But, this unit is from 1956, and there is no
A/C switch on the Volume control, only on the changer.

[electra225]

They tie one leg of the AC line to the phono motor plug since the power switch for the entire instrument is in the changer. Magnavox and many others used a separate power switch in addition to the switch in the changer. Confusing to troubleshoot sometimes because you forget one or the other is there. But the switch in the changer is still a three-way switch setup regardless of the presence of a separate power switch in the tuner. You can run the phono motor in a Magnavox console and not have the function switch set to "Stereo" that powers the changer. Strange setup. The motor is wired hot, but not really. Confused?

If you have a Magnavox stereo in, say, the FM mode, you can run the phono motor, since the function switch shunts the power switch in the changer. When you change to "Stereo" mode, the function switch than connects the switch in the changer as a three-way switch that will turn the entire instrument off totally when the last record is played and the changer shuts off.

[Hi-Fi-Mogul]

I would like to know ya'lls experience with Zenith disc capacitors.

I have seen comments on other forums that they
do not hold up over the decades, and should be replaced.

Have any of you experienced this situation with a Zenith ?

This unit is from 1956.

[electra225]

My experience with disc capacitors in any manufacturer's product has been good. I have never come across a bad one. Couplets the same. The TV guys are having issues with micas in certain higher voltage applications. I have replaced one confirmed bad mica, plus a couple on a guess with no improvement in performance. My personal troubleshooting procedure is to suspect almost any part in the chassis before I suspect a ceramic cap of causing the issue. I did hear something on one of the more popular TV repair YouTube channels that there were a couple cases of failed ceramics in TV chassis, but some of the circuits in TV are more critical as to component condition that found in audio work. Plus TV chassis have high votlage pulse voltage, which is a whole different kettle of fish than what is typically found in audio work. I'm real critical of "narrative" discussions on some of the various forums. You know what I'm talking about. "SMD", the 6X5 rectifiers burning your house down, 50C5's being the worst tube ever made, etc., etc. I also tend to be more critical of Zenith than perhaps what is fair, so I'll quit while I'm ahead there.

Are you having a specific issue that you suspect might be caused by a ceramic cap?

[Hi-Fi-Mogul]

I'm having some trouble checking the OPT primary coil
for continuity.

The OPT primary coil Blue wire (now green from aging) connects to
Pin 3 of the 6V6.

The other side Red wire makes several connections:
R15, then on to filter capacitor C1B, connected to
R17 and R16.

When I place my DMM leads on Blue wire on Pin 3 of 6V6, and any
of those other Red wire connections, I get no reading.

My meter has an audible continuity function along with the
Ohms reading.

Am I placing the meter leads correctly ?

Could the solder points not be conducting due to age ?

Is there another way to check the primary of the OPT ?

[electra225]

You are measuring it correctly. The surest way to check an OPT is by measuring voltage at the plate of the output tube, pin 3. If there is the correct voltage, the primary of the OPT is good. If there is no or extremely low voltage at the plate of the output tube, pin 3, there is a potential problem with the OPT. Next would be to measure voltage at filter cap 1B and compare to what is on the plate of the output tube. In that drawing, the electrostatic speakers are powered off the plate voltage of the output tube thru that 100K resistor. One caveat on how you are taking that measurement. The 100pf cap in the electrostatic speaker circuit may be giving you a false reading. I think I'd try seeing if you have voltage on the plate of the output tube. That might save confusion. Good luck.

[Hi-Fi-Mogul]

Very good information that I had not learned.

I'd also appreciate methods on how to safely hook up AC power to
the Amphenol plug that I have to jumper.

I'm thinking that I will go ahead with the re-cap first,
then doing a power up.

Maybe a bit cart before horse re: the OPT check, but if
the transformer checks bad after re-cap,
it will need replacement anyway.

[electra225]

I like starting with voltage measurements at the cathode, pin 8 of the 6X5 rectifier. If it is good there, then go to each positive terminal on the filter capacitors, then on to the plate of the output tube and so on. Run each leg of B+ to make sure it is the value it should be. If you reach a point where there is not the correct B+ voltage, you know where your trouble is. In the way of clarification, you would be measuring DC from the rectifier cathode on out the B+ buss. Common negative in your case would be the chassis. A suggestion might be to replace the filter caps, then get a baseline of operation. This way, you can tell of all the transformers and other "important parts" are good before taking the time to recap, then find you have something major open that will kill the entire project. Good luck.

If you are wanting to run the amp without the changer being in circuit, refer to comments I made previously. I can't see the terminal numbers on the latest diagram you posted. You would jump across the upper two terminals in that diagram. You might try, in lieu of using test leads, stripping a short length of wire and making a short jumper across the two terminals I cited. That might create less chance to short something out.

[Hi-Fi-Mogul]

Yes, I meant I was going to replace the power supply e-lytics first,
and proceed with your diagnostic advice.

I have some heavy gauge solid wire that I will use to make
an AC jumper, and tape it down with electrical tape to the
Amphenol plug, so it won't move.

I received 2 "pencil" 47 mF 450 V NIchicon caps, and
one 22 mF 450 V Nichicon, which did not come as
a pencil-type.

I placed all three as a group on the top of the e-lytic
multi-can.
It looks like there will be enough room for all 3
to fit in the can, yay !

[electra225]

Are those "pencil" caps the Nichicon PZ series? I like those. You can put 4 PZ capacitors in a Magnavox filter capacitor can. Navigating Mouser's website is not for the faint of heart.....

Sounds like you are on the right track. Good luck.

[Hi-Fi-Mogul]

Are those "pencil" caps the Nichicon PZ series? I like those. Navigating Mouser's website is not for the faint of heart.

Greg,
These Nichicon are UCS series. I think it is the current pencil
style product for them.

I'm now used to Mouser's website. And you can really home in
on what you need with the extensive search term base.

I have the muti-value e-lytic can off and cleaned up.

Now to examine the physical layout and hole drilling to
mount and solder in the caps.

My hacksaw cut was better, but since I did not want to pull
off the can, I had to jerry-rig the chassis on a work table.
I held the can/chassis with one hand, while sawing
with the other.

I colored the edge of the masking tape with a black marker,
after measuring the can circumference.
I matched the ends of the tape, and I then I had
a reference line for the cut.

[William]

Nice job Mr. Mogul. You are hired!

Bill

[Hi-Fi-Mogul]

Finished mounting and soldering in the 3
e-lytic caps.

Since the chassis is "ground", I was able to use the
twist mount lugs of the old multi-value cap can
for the neg leads of the new caps.

I had to cut out one wax/paper cap, so I'll go ahead
and put in a film cap temporarily, then continue
with checking the circuit.

I ordered a set of mini-grabber leads from that person
in Chicago via e-pay. They are supposed to be well-made.
When those come in, I'll start the further check-out.

[electra225]

Good clean work, Mr. Mogul. Looking good!!

[William]

Someday I will try stuffing a can with new caps but that would require me ordering the skinny caps to fit inside the can. I have a good supply of caps that I purchased from Sal, it was one of his kits where you got 50 of everything. Being a cheapskate, I will probably wait until I deplete my stock before I order the skinny caps.

Good work, Mr. Mogul. What's your next step with your can capacitor, do you put the part you cut off on top?

Bill

[Hi-Fi-Mogul]

Good work, Mr. Mogul. What's your next step with your can capacitor, do you put the part you cut off on top?
Bill

Bill,
Yes, after everything is checked out, I will use a piece of
aluminum tape to attach the sawed off piece of can.

I made a mark on the can before I cut it off, for
a reference to put the cut off part back on.

[William]

Thanks, Mr. Mogul.

Bill

[Hi-Fi-Mogul]

I've started checking voltages now that I have the
new grabber leads.

The electrolytic filter cap voltages are good.

The original 12AU7 had one bad side, showing one side with a
high plate voltage of 247 VDC.

A new tube has both 12AU7 plates' voltage of the dual triode
back within schematic specs.

But the grid voltage on Pin 2 (V1B) is 3.7 volts and it
should be zero volts.

Grid voltage on the other half of the 12AU7 Pin7 (V1A)
is 0.1 Volts.

I get crackles and pops on the speaker when I touch the 12AU7
Pin 7 grid with an insulated wire probe.

I get no crackles/pop when I touch the Pin 2 grid.

Should I complete the re-cap and then see what happens ?

[electra225]

You have an extra stage of amplification on the grid of V1A. Tickling the grid of V1B will give a smaller output due to this. It sounds like you are doing okay at this point. Finishing the recap then see what you have. I think you'll be fine. Good luck.

Do you get a nice hum when you touch the hot terminal of the volume control? I read in a book one time that a healthy audio amplifier responded with the same growl when you touched the hot terminal of the volume control that a tiger does when you twist his tail. I've never forgotten that.....

The only way I see to get positive voltage on the grid of V1B is thru C2 if it is leaky. Measure DC on both ends of that cap and see what you get. You should have plate voltage from V1A on one side, nothing on the other. Capacitors only pass AC when they are doing their job.

[Hi-Fi-Mogul]

I finished replacing the other caps and voltages
are much better.

On the 12AU7 V1A plate pin 6, the voltage is a bit
low at 75 V, where the schematic lists 90 V.

V1A grid pin 7 is 0.2 V.

12AU7 V1B plate pin 1 is 71 V, schematic value 75 V.

V1B grid pin 2 is 0.06 V.

I get a good buzz off of the phono cable connector
when I touch it with a wire.

I will let it run tomorrow for several hours,
to make sure a resistor does not go out of
spec.