An Emerson with a 19AP4??

[dieseljeep]

Originally Posted by compucat

Motorola used to make a 19 inch set. I wonder if it used the same tube?

I followed Bob Anderson's restoration thread on the Motorola 19K1 and it used the 19AP4.
IIRC, Zenith/Rauland, Dumont and RCA used the same designation.

[Kamakiri]

Well viewing my current frustrations with my 730TV2 and the RA-110, I figured I'd set those aside for the moment and see what I can do with this set.

Much to my dismay, there are FIVE capacitors underneath with leads cut on the one end, one looks like it was just a sub to test something (sigh).

Okay, not impossible, just check out the schematics and see where they go, right? First one I started on I can't figure out. It's a .05 uF 400V with the foil side cut. It comes off of the vertical linearity pot. According to both the Sams and the factory Emerson schematic, this cap shouldn't be anywhere in the circuit. I have no idea where it goes or why it would even be there.

Ideas?

[Username1]

I bet it was a replacement, maybe someone replaced a buncha caps looking
to solve a problem, and just left the old ones hanging there..... I use to run
across that now and then.... Parts soldered to the old leads on top of
the pc board as well..... Lotsa crazy stuff out there.....

Get some solder wick and remove the end of that one with the green crud on
the leads and see if there is a buncha wire still left on that tube socket.....
If it was cut, and not removed with a soldering iron, then the little wire
is still there.....

Do the other parts look like they easily went somewhere....?
Well then they did it more than once.....


.

[dieseljeep]

Originally Posted by Username1

I bet it was a replacement, maybe someone replaced a buncha caps looking
to solve a problem, and just left the old ones hanging there..... I use to run
across that now and then.... Parts soldered to the old leads on top of
the pc board as well..... Lotsa crazy stuff out there.....

Get some solder wick and remove the end of that one with the green crud on
the leads and see if there is a buncha wire still left on that tube socket.....
If it was cut, and not removed with a soldering iron, then the little wire
is still there.....

Do the other parts look like they easily went somewhere....?
Well then they did it more than once.....


.

The component with the green crud on the leads appears to be a large wattage porcelain resistor. I never saw a capacitor that corroded like that. Maybe the pot is partially open and someone subbed the resistor for it.

[Username1]

I couldn't tell what it was.... Yah I never did see a cap look like that either.... They could
have done anything, and the circuit could have been changed too....
Even on a different computer I can't tell what that part is....

.

[Kamakiri]

It's a ceramic 30K resistor, wattage unknown. There are 4 other similar ceramic resistors in this set, all with this same type of odd corrosion on the leads.

That's a good idea about melting the solder and checking for loose wire ends. From the length of the cap, there's only 3 or 4 places it could attach. I'll give it a go

[Kamakiri]

Originally Posted by Username1

Get some solder wick and remove the end of that one with the green crud onthe leads and see if there is a buncha wire still left on that tube socket.....
If it was cut, and not removed with a soldering iron, then the little wire
is still there.....

Squirrel boy gets my Genius of the Day award for this one! Used my solder sucker on every point that this cap could go to, and sure enough, found it!!! Thanks for the tip!!!

And now, on to the rest

[Kevin Kuehn]

Still there's the possibility that it was put there by some hack, along with that 30k ceramic resistor. I'd trace the connections in the vert lin circuit against the schematic and see if anything makes sense. That 30k is a long way out from the 470 in series with the pot shown on the schematic.

[jr_tech]

Where did it go to? is it C-63?

jr

Edit add: Is the 30K resistor *marked* as 30k or could it actually be the 470ohm resistor that has changed value?

[dieseljeep]

Originally Posted by jr_tech

Where did it go to? is it C-63?

jr

Edit add: Is the 30K resistor *marked* as 30k or could it actually be the 470ohm resistor that has changed value?

I think it's a wire wound resistor. That's one crazy value change!
Neither schematic shows the wattage. Emerson seemed to use that type of high wattage resistors and on most, the leads corroded like that.
One the Sams, they show a -165 volt bias line.
BTW, what volume Riders is the Emerson sourced schematic in? Maybe, there's a production change bulletin, showing the circuit changes.

[Kamakiri]

Originally Posted by jr_tech

Edit add: Is the 30K resistor *marked* as 30k or could it actually be the 470ohm resistor that has changed value?

No, it's actually marked 30K.....I didn't test it.

Whoever was working on this set last must have either had no idea what he was doing, got frustrated and quit, or discovered something bad and said "the hell with it". I'm hoping it's not the latter. I found and traced all of the disconnected caps, which coincidentally were all in one row between the 2nd sync amp and the vertical output.

[jr_tech]

Originally Posted by Kamakiri

No, it's actually marked 30K.....I didn't test it.

Not shown in the schematic that I have for what appears to be the same (or similar) set (PF set 126-folder 5) nor as an indicated substitution/modification... where does the other end connect?

jr

[John Marinello]

Originally Posted by dieseljeep

I ran across a lot of Emerson's, but never a 19" roundie. It must be the last issue 19AP4, straight gun, no ion trap.
I've seen several 19" roundie sets, Admirals, RCA's and of course, Zenith Portholes. Emerson 19" roundies, must be rare.

The 19AP4C was aluminized.

[dieseljeep]

Originally Posted by John Marinello

The 19AP4C was aluminized.

I have never seen a metal cone crt, that was aluminized.
The "C" probably only designates an improved or latest version.

[dieseljeep]

Originally Posted by jr_tech

Not shown in the schematic that I have for what appears to be the same (or similar) set (PF set 126-folder 5) nor as an indicated substitution/modification... where does the other end connect?

jr

I was just looking at the schematic again. In the picture, the vertical linearity pot is a rather high wattage type. The 470 ohm resistor seems to make sense, even if the pot is turned to minimum resistance, there is still bias on the cathode. I also notice the 6K6 is triode connected. I would restore the circuit to original, per the schematic.
I find it strange, that some of the vertical circuitry is so far away from the sweep tubes. Rather complicated set to work on, plus the wiring is like a rat's nest.