Valentine's gift (or is it a shameless trick?)

[Phil Nelson]

Fixing the socket terminal was a good idea. I got a wire through the side of the socket, wrapped it around the little holed piece on the inside and the old stub on the outside, and soldered. Left a pigtail until I'm done messing around in that area. It won't survive caveman yanking, but the original terminal wasn't that sturdy, either



With a .1 uf cap in place, I measured 118ma cathode current with the Triplett meter. That's the middle of the 100ma-140ma range given in the schematic. I'm going to quit stressing over this, since the voltages on the HOT and general performance are also normal.

The vertical (drive?) line definitely becomes more visible if you turn the fine tuner CW to the point where focus becomes too sharp and you start to see ghosting contrast lines on the sides of objects. If you back off on the finer tuner, it basically goes away. I'm crossing that off the problem list, too.

Re the linearity, I previously replaced three resistors on the sweep board (R65, R69, R70) and that improved it somewhat. I just replaced three more (R66, R67, R68) and it's about the same. Please don't tell me it's the vertical integrator K1; I have built replacement integrators before, but they're kind of a pain.

Thanks,

Phil Nelson

[wa2ise]

Looks good. I'd probably just solder the other end of that pigtail to the terminal of the other tube socket (gently!), maybe creating a loop with the old wire to hold the pigtail to the terminal when you solder.

As far as vertical linearity goes, did you replace the vert out tube's cathode bypass cap? I had one go bad, and IIRC with it bad I couldn't get reasonable linearity.

[wa2ise]

So how's it holding up? Hoping its

[marty59]

Maybe this model Philco is picky about Vertical tubes like our Barber Pole models and you have to go through a bunch of 'em to find some that perform well enough to correct that linearity issue.

[Phil Nelson]

It's holding up so well that I have gone on to the next project. Miss America plays all day long to entertain me in the shop until we decide where to put the set.

The linearity is just bad enough to be annoying. I have replaced practically every resistor in the vertical section, even the two on pins 9-10-11 of the yoke socket.

Swapping tubes is a good idea. I tried subbing the 12AU7 but don't have a 6CM6 (vertical out) on hand. I went on a treasure hunt and found many odd & wonderful tubes -- why do I have two dozen 6BH6s? -- but no 6CM6 or equivalent. May as well order one.

I was a little disappointed in the bass response and even thought of hotwiring a new tone control. Then I put the back cover on and, duh, the bass sounds fine.

Phil Nelson

[Phil Nelson]

Originally Posted by marty59

Maybe this model Philco is picky about Vertical tubes like our Barber Pole models and you have to go through a bunch of 'em to find some that perform well enough to correct that linearity issue.

I tried a couple of new 6CM6 tubes and now I can get closer.



Re-centering the vertical also helps (duh). Strange yoke gizmo, by the way.

Horizontal linearity ain't perfect, but with no linearity adjuster I think I will call this good enough. The next project is already underway.

Here's the usual gabby article:

http://antiqueradio.org/PhilcoF4626MTelevision.htm

Thanks for the advice.

Phil Nelson

[old_coot88]

Originally Posted by Phil Nelson

.

Here's the usual gabby article:

Phil, your gabby articles are far and away the most entertaining, engaging and informative of any out there. I always settle into one of your resto sagas knowing it's gonna be enjoyable to the utmost.
Bill(oc)

[DaveWM]

indeed the gabbfest is good, as is the consistant style (tube layout etc..).

I have been using the cut off the can and leave the base intact approach lately as well on sets where I dont want to spend a lot of time on.

I use a bone saw style for the cutting, seem them on those late night infomercials, the receprocate and you can plunge cut direct into the can with very little access. A bit pricey though...but fast.

[Phil Nelson]

Originally Posted by Phil Nelson

With a .1 uf cap in place, I measured 118ma cathode current with the Triplett meter. That's the middle of the 100ma-140ma range given in the schematic. I'm going to quit stressing over this, since the voltages on the HOT and general performance are also normal.

Speaking of current measurement, this week I got my hands on an HP 428B DC milliammeter, which gave the same reading as my old Triplett meter, so I guess the Triplett's good enough for government work.

Andy's method worked like a charm. Clip the 428B probe over the HOT lead and measure away. Easy as pie. On this set, the Width control affects the current directly, so I turned it down to around 100ma, which gives reasonable width & picture.

I got the 428B to use on my color roundies, but it has already earned back the few shekels I paid for it, and now I feel better about just letting this Philco play away. After warming up a couple of minutes, it looks fine without the CRT brightener, so I tossed that in a box. Who knows why they put on a brightener in the first place? Maybe that was a quicker solution than diagnosing some peskier issue.

Phil Nelson

[Kevin Kuehn]

Originally Posted by Phil Nelson

Andy's method worked like a charm. Clip the 428B probe over the HOT lead and measure away. Easy as pie. On this set, the Width control affects the current directly, so I turned it down to around 100ma, which gives reasonable width & picture.

I missed something. What exactly was Andy's method?

Kevin

[Phil Nelson]

Sorry, the method is just what I said (only too briefly). The 428B is a DC milliammeter whose clip-on probe you can place around the HOT lead to measure the current. Andy C. has mentioned doing this before. I thought I had referenced that somewhere earlier in this thread, but maybe I just imagined that part.

Anyhow, it seems to work, and it's easier than lifting one end of the cathode lead to measure. Perfect for a lazy guy like me.

The manual is at hparchive.com. Talk about your cosmic gizmo. Be the first kid on your block with a second harmonic flux-gate-type magnetometer probe!

Phil Nelson

[old_coot88]

Originally Posted by Phil Nelson

...Be the first kid on your block with a second harmonic flux-gate-type magnetometer probe!

That sounds like sumpthin' out of 'Back to the Future'.



oc

[Kevin Kuehn]

Ah... so it's a clamp on amp probe. For a minute there I thought you were just clipping the lead of a convention VOM over the HOT lead and measuring current. I thought maybe somehow with the HV it was jumping through the insulation.