Score!!!!

[nasadowsk]

So, I'm busy driving the Saturn around trying to figure out a typical saturn problem, when I pass a garage sale. Well, screwit, i'm bored so I go in.

Nothing in the basement.

Nothing on the main level.

Upstairs, I'm walking around and I see a cute B&W Zenith, mid-late 60's.

And as I'm looking at it, I'm wondering "Why does a cute B&W Zenith Portable have a color control on it"

Well, gee, it's color!

For $15, I got it plus the stand it was on.

It's a 15" (15LP22) set. Hybrid - 3 transistors and ??? in the IF strip (it's got a little box for IF). 6LF6 output.

The chassis is a 15Y6C1. I have no idea what year - but I think 68.

It works It's a little tired, but it's darn watchable. Needs the convergence done (duh). Noisy controls. Dusty as heck, but no smokers in the house. Cleaned up well - the chassis is nice. I'll get pics.

No 6BK4! Must be a pulse regulator.

Anyone got a schematic or other info on this thing? Or any general info? It looks like it's an early portable - it's HEAVY and has a big friendly power transformer.

The sound's buzzy/distorted, but other than that, everything's nice. A bit soft, but nice. I'm gonna stick it up on my shelf aboce the computer once I get it fully tunned up..

Moral? Keep looking. You never know when a cute little color TV will pop up.

[andy]

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[nasadowsk]

Ah, yes, I missed the 5 at the end when I peeked in there.

Neato - it's a first!

Mine works, but has minor horizontal foldover and HV regulation that stinks - it'll drop into the mid teens on a bright picture. I'm gonna change out the caps in the horz section and also get a few electrolytics.

It looks like it hasn't been repaired much, likely because it hasn't been USED much. It came out of a little old lady's home. Sat unplugged for who knows how long?

The CRT is bright, doesn't shift color as it warms up. I'm guessing it's pretty much perfect. Though, oddly, it has a missing phsphor dot on the screen...

No green demons on the faceplate. It's *perfect*

$15! A bargain! And a heavy box, too.

Wow, it's got lots and lots of little diodes in there.

I could use a copy of the schematic, since the set's not perfect.

So far:

The HV regulation is pretty bad, at least vs what I'm used to on roundies. Maybe this is normal?

Horizontal foldover

Focus control pegged at one end, still a bit fuzzy.

On again/off again color (yes yes, I know, it's the 6GH8!)

Hue control goes from puke green to flesh, not puke green to flesh to smurf blue.

Hey! It's got a rare earth tube! Reds so red, they're orange

I need a spot in the room for it. Probbably on top of my 25LC20 chassis console....

[jstout66]

Cool!!! It's a "good day" when you can find a set that's 1) small 2) cheap 3) a Zenith! Those sets are pretty durable and it sounds like your problems are mostly tube related. It's sounds like your horizontal output tube needs changed. But that tube is expensive so I'd check it first. If it's bad, that could cause your HV Regulation, foldover, AND focus problems. The on-off again color problem is most likely a tube. I don't think Zenith used 6GH8's in that set, but it's been years since I've seen one of those so I can't remember the tube layout. The "buzz" has got to be a sync/agc tube, which would cause the "buzz" and could cause the "on-off" again color as well. As for the "hue", the set probably needs the control cleaned and possibly the set needs "re-tracked" As in example of how much testing all the tubes can make a HUGE difference, I just got a 1967 RCA B&W portable off eBay. The set "worked" but the contrast and focus seemed a tad crappy AND you had to fine-tune it all the time. I took the back off and discovered the set had never been worked on, and fully expected many bad tubes. I checked em all, and lucked out and only had 4 bad ones. Both "IF" tubes and both tuner tubes. Got the tubes yesterday, popped em in, and man.... I didn't expect that huge of an improvement. Now I've got great contrast and focus and I can pull in tons of stations! In your case I'm sure tube replacement will solve most, if not ALL of your problems. Again, what a great find!!!!!!

[Chad Hauris]

These Zenith portables appear to use a very robust chassis, it seems like they are very similar to the large console chassis. These usually use a 6HV5? HV regulator, yes it is a pulse regulator. You can probably try a tube subsitution check against the tubes in your console if it is a tube type as many tube types should be the same between both.

[andy]

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[nasadowsk]

I haven't peeled back the layers of stuff around the CRT yet. Though I should clean the dust off around the HV cup.

Where is the chroma tweaking coil? I'm guessing right near the 6GH8?

Hey - andy - any way I can get a copy or even computer scan of the schematic from you? It'd be useful. Thanks!

[nasadowsk]

BTW - I've cleaned off all the tubes, and most look origional. The 6LF6 is, the damper is. There's a few zeniths (7 pin) with red writing on them, and one post 60's RCA (I think a 6GH8 - what a surprise!). I might just retube the whole set, but that horz output is $$$

[jstout66]

damn.... you're not kidding on that 6LF6 being expensive. I checked it out from the company I buy tubes from (vacuumtubesinc.com) and new it was $60.00. They also have it used for $32.50. Jeeezzzzz, I knew they were expensive "back in the day" but to be so expensive still?!? What the hell?? The rest of the tubes wouldn't be too expensive, but you should try to test the ones before replacement, to save $$$$.

[nasadowsk]

If you google for the 6LF6, you'll find that not only do hams like it ("Fetch it out of one of those worthless 60's color TVs"!), but a certain sect of the audio fringe has a big thing for it, and of course, for those guys, only the 'correct sounding' tubes work. I guess on the bright side - if either sect decides they need new ones badly enough, Sovtek or such will make them...

Supposedly, they were in production into the 80's, and lots of TV sets used them. I suspect something else is at play here.

Ever price a 6BK4 in recent years? Tell me that makes sense too?

[jstout66]

6BK4 lists for $32.50?!? Damn... now why the heck is that one so high? I can't imagine that one being used for ham stuff. I know the 6JE6 is, yet that one lists at $22.50. I was messing around with my Chromacolor 4 tube hybrid and see that it uses a 6LF6. I hope that one doesn't go out anytime soon. The last tube I had to buy that I about keeled over from on the price, was the 1L6. As far as I knew that was one of the highest price tubes out there. Guess I was wrong huh????

[Charlie]

Originally Posted by nasadowsk

I might just retube the whole set, but that horz output is $$$

I found a couple of 6LF6's out in the garage. They came out of a big box of used tubes that I got from a local tv man. It does not appear that they ever overheated. I'd check them, but my tube tester does not have a listing for it (my tester is from the stone-age) and I don't have any sets that I can swap-check them in.

You're more than welcomed to them if you'd like to give 'em a try. PM or email me your address. If I come across any others, I'll toss them in as well. I would think that at least one of them should do you good.

[Steve Hoffman]

Charles,

Love your Curtis Mathes!

[drh4683]

Great find! Those are great portables! The 15YC615 is from 68 and went to 69. Ive got both models that they made. Ive done a bit of work to both of them, and yes, Ive experienced tint range problems with one. Basically, the control was all the way in one direction to get a normal looking flesh tone. That was corrected by placing the tint control in the mid position, and adjusting the slug in the burst amp plate coil untill the flesh tone looked correct. Thats the simplest way. Mine also had a problem with the color killer circuit. Couldnt get the color to kill regardless of the setting. Turned out to be an open crystal diode in the killer circuit. Yes, the 15YC615 has a 6GH8 for the 3.58 osc./reactance. Check it for shorts! We cant say enough how bad the 6GH8 is! The most trouble prone tube ever!
As far as focus, these sets natrually have a soft picture, even when focus voltages are correct, and the crts are in great shape in mine. Dont feel bad about the picture, thats just the way they are. The latter models had an efficiancy coil in the horiz. circuit so you could adjust the regulation. On the earlier runs, adjusting the 21.5 kv is the only way to set the reg.
Here is the proper way to adjust hv on the 15YC615:
warm the set up for a few minutes
color all the way down
set up switch in "set up"
test the line voltage at the plug. For every volt less than 120volts, subtract 80volt from the HV reading. So, if you read 117 volt, you need to take off 240 volt (80volt x 3) from 21.5 kv, making an adjustment of 21.260 nessisary.

Your set may or may not have the efficicancy coil. You will see a shorting clip near the horiz. out tube. Remove it, insert a mA meter across those two terminals (0-300 mA scale) and adjust the efficiancy coil for minimum reading on meter. The coil is located behind the HV cage (tward the front of the TV) Easiest way of adjusting it is to remove the bottom cover and adjust.

Pictured is the burst amp plate coil, its just beneath the right side of the delay line in the photo. Adjust that for proper tint.

Next pics are the 2 portables with the 15YC615 chassis. These are the only two styles they made, so yours must look like one of these. The last one pictured is the one that gave me most trouble. Found that one on the curb 2 years ago. Main problem was a shorted filter cap, then it was downhill from there with problems. Now its fixed so it works pretty darn good now.

The other one (gold cabinet) worked when I found it, and needed nothing but tubes in various places.

[nasadowsk]

Mine looks like the firsat one you posted, only the door's gray, not white.

Hey, I adjusted a coil right near the 6GH8, between the tube and the chassis edge. I think that's the frequency coil, but it had an effect on the tint *shrug*. I spun *it* for good flesh tones and did well.

Trouble is, the core broke And, the coil just 'north' of the 6GH8, I twiddled first, thinking it was the burst amp plate. It didn't do anything to the picture at all. Hope it's something easy - 3.58 osc output?

I adjusted the HV by turning the brightness to nothing and setting for 21.5kv. Well, I gotta retouch the convergence so I'll recheck it.

The infamous 6GH8 was bad. You'd have to jiggle the tube to 'bump start' the 3.58mhz osc.

What's those coils around that tube do? I'm guessing one's the rough frequency, the other might be the output? Oh yeah, and can you zoom back slightly on the burst coil, I'm having a bit of trouble locating it (which way is the front and back) and I don't want to diddle the wrong coil again! I'm trying to ID all the coils in the burst / 3.58 mhz oscilator circuit, since that's where my big troubles are right now.

What point can I ground in there to let the oscillator run free? I grounded W, but that killed the color.