Watch out for mice.....OMG!!!

[Kamakiri]

Sure does look like the same set. At least now I see that I have to pull the picture tube to get in there, probably should anyway. I'll take pics over the weekend when I pull the tube, and we'll see what's inside

I've been working on two Sylvanias simultaneously.....it wasn't planned, it just worked out that way. Buttoned up the other one last night

This one belongs to a customer in MD.

[Kamakiri]

After a complete recap, sans one bumblebee that I need a positive ID on , the set got power last night for the first time, slowly on my homemade variac.

As the tubes lit up, I got a loud buzz from the speaker, and nothing exploded , so after about 15 minutes, I slowly applied full power.

The buzz in the speaker decreased, and I got normal static on the sound, which was absolutely perfect. No raster, and I couldn't see those little HV tubes glowing (the cover was on, so I have to power it up again with the cover off, but I assumed I'd see some kind of light coming from there....but then again I can't remember seeing any tremendous glow on a 1B3).

With no raster, I still wanted to observe the set for a bit to see if anything else would shake out (like smoke or sparks, primarily...lol), and all seemed stable. I disconnected the variac, and plugged the set directly in to try once more before bed. The set powered up with the "BOOMP" noise that is common to some of these, but this time, to a bit different result. The static from the speaker was lower, and gradually turned into the same buzzing noise I heard on power up, meaning to me that the chassis was slowly losing voltage after the cold start. I pulled the plug, and that was where I stopped for the night.

First thing I have to do is ID and replace the bee. Next, I have to remove that cover and try a slow power up to see if I'm getting anything out of those little HV tubes. WILL I visibly see anything on those?

Thoughts as to where I should go next with the set? Oh, and what's a safe way of checking HV from the picture tube anode? I've heard of a screwdriver technique, but frankly that gives me the willies

[Charlie]

Yes, placing the screwdriver within an inch of the anode lead should produce a nice light show if you have healthy HV. Perhaps a little closer if the HV is weak.

If you disconnect the anode lead from the CRT and it's just dangling there, as you place the screwdriver close to it, it might actually pulled the lead toward the screwdriver.

Doesn't the HV go thru the horz windings of the yoke before getting to the CRT? I know it's less likely to have a yoke fail than your HV module thingy, but it would be a quick and simple to check the yoke connection and also put a meter across the leads for the horizontal winding to make sure there's nothing open.

Also... you mention a leftover bumble bee... where is it? Could this cap be the problem? When I recapped my Halolight years ago, I didn't get any HV at first. Turned out, I missed a small paper/wax cap... something like a .0047... was hiding under another component. As soon as I changed it, HV came in just fine.

I used to purposely check the HV with a screwdriver if someone was at the house while I was working on a set... and do some mad scientist laugh while doing it. I recall my younger brother's eyes get wide one time when I did that... and he walked out of the room saying The hell with that... I'm outta here!! My brother was not a fan of playing with electricity.

[Kamakiri]

I know that's the way to do it, but I'm just too freaking chicken

Hell, to discharge HV before I work on a set that I've tested, I empty my pockets, and hold the end of the test lead which I'm using to discharge the anode, with a REALLY thick towel all bundled up. Because towels are the best HV insulator out there, you know

Seriously, though, what type of safety precautions does one need to do before doing this....other than the aforementioned? Insulated screwdriver, don't do it in the bathtub, etc?

[jr_tech]

Originally Posted by Kamakiri

Next, I have to remove that cover and try a slow power up to see if I'm getting anything out of those little HV tubes. WILL I visibly see anything on those?

If they are good, and getting power, in a semi-dark room you should be able to see a faint yellow-orange glow reflected inside the plate region even if you can't get in a position to *directly* observe the filament.
jr

[Electronic M]

An HV probe is the most quantitative way of checking for HV.
Another thing that you can check with is a neon bulb. It should glow just from the field around the HOT cap lead.

[Kamakiri]

Got that bumblebee in, and also redid the connections on the socket on the back of the picture tube (they wiggled loose). I've got audio now, as in it actually picks up an over the air agile modulator broadcast. Good sign there

But, I assume, no HV. Close up eye shot reveals absolutely no glow whatsoever in those funky HV rectifiers. Since they can't really be checked, might as well start searching out replacements?

Couple notes: flyback looks like brand new, and replaced the .0004 @ 10 kV cap in the HV section already, with all leads dressed properly. Picture tube tests good.

[Reece]

One more note on HV testing: first put on a fresh pair of Depends...

[Electronic M]

Well you could connect a battery of about the same voltage the filaments are rated for to the filament of a tube then use a separate battery and a lightbulb connected both ways to test for forward current, and reverse blocking. And do the same for the other tube.

If you have a spare octal base lying around you could probably wire each tube in turn to the base like a similarly specked octal based HV rectifier tube, and then use the test settings for the octal tube to test it in your tube tester.

[holmesuser01]

Originally Posted by Reece

One more note on HV testing: first put on a fresh pair of Depends...

Also work with an already empty bladder...

The worst shock I ever got on a set was from the 600 volt boost that Sony used at one point... It basically grabbed me. I can still feel the burning 20 years later in my hand. I had to push away from the set with my legs, and hit the wall behind me HARD.

I knew the voltage point was there, but was distracted by something going on outside the garage area.

The only other time was working on an RCA chassis with the metal 21AXP CRT. I had one hand in there reaching for the horizontal oscillator tube... I was going to rock the tube in the socket to see if I had found the bad board connection that was causing the drive to blip out for a moment after it got warmed up.... Apparently, I fixed it, but when I moved away from the tube, I felt the hair on my hand stand up, and POW!! I found myself against the wall, and my dad saying, "Are you OK?"

[jr_tech]

Originally Posted by Kamakiri

But, I assume, no HV. Close up eye shot reveals absolutely no glow whatsoever in those funky HV rectifiers. Since they can't really be checked, might as well start searching out replacements?

Is the horizontal oscillator running? Horizontal output working? The filaments are supplied voltage by 2 windings on the HOT. Unlikely (but possible) that *both* the 5642s have open filaments.
jr

Edit add: Perhaps unsolder the little critters and test as Electronic M suggests.

[holmesuser01]

I have a feeling that there's no horizontal happening.

[Kamakiri]

Originally Posted by holmesuser01

I have a feeling that there's no horizontal happening.

Wait a minute. You're right. I DIDN'T hear the horizontal oscillator running. The chassis was dead quiet.

So, I have all new capacitors, all tested good tubes, and no schematic. Hm. What's next to check?

[holmesuser01]

I'd be checking for drive from the oscillator, B+ on the output tube, the damper circuits. Could easily be something like an open resistor... Is the yoke OK, too? Does the horizontal output actually get HOT, other than filament hot? So many possiblilities!

I think the schematic would be something worth getting at this point, for sure.

[jr_tech]

Originally Posted by Kamakiri

What's next to check?

Is there a fuse between the power supply and the Horiz Output Tube?

jr