Desperately need help on Raytheion model M-1602

[Bill Cahill]

This is an old project I started years ago, then, it went untoubhed for 18 years.
As it stands now, I've don a complte electrolytic re cap, replaced a number of off value resistors, and, bad tubes.
I get reception with audio, and, picture from cold start.
Vertical is still short, but, stable. I have horizontal discriminator issues.
But, that's not the worst of it.
After it's on a few min. the picture starts getting darker, and, shorter on right hands side.
Then audio volume goes down, and, picture turns negative, and, much darker.
Soon, my raster goes complletely dark, and, sound is very weak.
I removed the high voltage cage today in desperation. I felt the flyback. Core, and, hv donut were warm to the touch. Does this mean the flyback is failing, or, what? If not that, can anyone help me on what's going on here??
No wax has melted yet, but, I'm worried about flyback getting warm, and, the fact that raster completely dies out.
Please help, guys.
Thanks.
Bill Cahill

[Charlie]

It sounds like the B+ is slowly taking a dump as the set warms up... because you are experiencing audio, video, and HV problems altogether. If your B+ is going down, your flyback could start to get warm. Connect your meter to the B+ and watch it as your symptoms develop.

The electrolytics you installed... are they fresh stock? What kind of LV-rectifiers is it using?

[Sandy G]

Maybe its Haunted !

[snelson903]

Originally Posted by Sandy G

Maybe its Haunted !

youll have to call ghost adventure's and have zack run around your house . lol

[old_coot88]

Is there any whiff of scorched scent coming from the flyback? (Old servicing adage: "the nose knows.") Any sign of red plating in the H output tube?

[Sandy G]

Those stupid jackasses wouldn't know a ghost if one came up & went "Boo !" at 'em....And what's the deal w/the guy's HAIR ? Didn't his mommy ever show him what a hairbrush is for ?!? Him & that Giorgio Tsoukalos character on "Ancient Aliens"....Sheesh !

[earlyfilm]

By its model number I assume that you have a 1950 or 1951 16 inch set.

The only schematic for Raytheon from that era that I have is the M-1612B or 16AY28 chassis.

Lets think about this problem one step at a time.

Originally Posted by Bill Cahill

I get reception with audio, and, picture from cold start.
Vertical is still short, but, stable.

If the vertical height is stable, that tells you that your B+ seems stable.

Originally Posted by Bill Cahill

I have horizontal discriminator issues.

But, that's not the worst of it.
After it's on a few min. the picture starts getting darker, and, shorter on right hands side.
Then audio volume goes down, and, picture turns negative, and, much darker.
Soon, my raster goes complletely dark, and, sound is very weak.

OK, this probably is not an high voltage issue, but lets eliminate that first.

Put a HV probe on the HV from a cold start and see if it drops.

If you don't have a HV probe, use a plastic ruler and a grounded jumper and measure the length of HV spark to determine if the HV is dropping.

A horizontal sync issue might lower the HV a little but probably not over 20%.

(The reason for eliminating HV issues first is, depending on how the set gets its keying signal, sometimes an AGC issue can be traced to a corrupted keying signal due high voltage sweep issues. This probably would not happen on the M-1612B chassis as the schematic indicates that Raytheon gets the keying info from the video amp which is typical of the era.)

Correction: Oops! Had a disconnect between the brain and fingers. The keying pulse comes from a winding on the flyback while the reference pulse comes from video amp.

Now let us get to the issue of:

Originally Posted by Bill Cahill

. . . . audio volume goes down, and, picture turns negative . . . .

Your set is talking to you and screaming "AGC overload!"

First step turn out the lights and see if the any tube in the IF, tuner, vid sep, video amp, horiz sync and horiz osc start to glow purple when this happens.

If no result, recheck the tubes in those circuits for gas or grid shorts after they have warmed up in your checker for much longer than you did the first time.

If nothing is noticed, disable the AGC output and manually control the AGC with a battery and fader. This may better help you isolate the problem.

If you have a scope, check wave forms in AGC, horiz sync, horiz osc, and on AGC line.

Hope this helps.
James.

[Charlie]

I have a similar Raytheon, but with with the metal round crt... I think the 16AP4. Mine had a lot of tired parts, but the thing I remember most was the 3 resistors in the IF section... each IF stage had a resistor in the same spot (can't remember at the moment what it was) and each one had gone way up in value the same way causing a very weak signal.

The tuner is built like a tank... you have to have a really good grip to crank that knob, and when each channel "clunks" by, you can feel it in the floorboards!

Re-capping this chassis is pretty easy... plenty of wide open spaces under the chassis to work with.

Curious... you said you started this project 18 years ago.... is that when you changed those lytics? Or did you change them very recently?

[snelson903]

Originally Posted by Sandy G

Those stupid jackasses wouldn't know a ghost if one came up & went "Boo !" at 'em....And what's the deal w/the guy's HAIR ? Didn't his mommy ever show him what a hairbrush is for ?!? Him & that Giorgio Tsoukalos character on "Ancient Aliens"....Sheesh !

i know me and my wife laugh at that guys hair everytime we see it ,its like he was in a explosion or something and zak cant make up his mind what dew to were,its probley who's ever is incharge of that they think its in style or what hollywood thinks is . lol

[cwmoser]

Charlie, I too have a Raytheon that uses the 16AP4.
I need to pull my chassis and check the resistors in the IF.
Thanks for the heads up.

These Raytheon portholes have pretty neat chassis layouts. Its the easiest chassis I have ever recapped.

Carl

Originally Posted by Charlie

I have a similar Raytheon, but with with the metal round crt... I think the 16AP4. Mine had a lot of tired parts, but the thing I remember most was the 3 resistors in the IF section... each IF stage had a resistor in the same spot (can't remember at the moment what it was) and each one had gone way up in value the same way causing a very weak signal.

[Bill Cahill]

Darned! I'm not getting e mail notices from this site.

Here's the scoop.
First, it was a total recap 18 years ago, including electrolytics.
At the time I re started it a couple of days ago I found my electrolytics had gone south. Some were oozing, and, bulged.
I re replaced electrolytics.
Just discovered this morning, two things...
1 a low voltage electrolytic on the vertical osc. had openned up.
2 I had missed the 10 mf 160 volt capacitor going to damper for boost.
That cap was also bulged, and, electrolyte had oozed out.
I will be replacing those today.
I will also probably re replace the cathode bypass on vert. output.

Thanks. I'll look into those I F resistors. I'm noticing now that some channesl are somewhat snowy, and, that's on cable.
With that bad damper cap I'm sure it wasn't helping matters any....

Vert. started out full two days ago, but, was working its' way down hill.
It's now over two inches short on the bottom.

No, i think it's 1949. I'll look at sams on it to see when it was produced.
And, model is C-1602. It's in the same sam's at the M-1601.
I'll be back on the set this morning, and, will let you know the results.

And, though not that much, the power supply voltage had been dropping a little.
Thanks, guys.
Bill Cahill

[Bill Cahill]

By the way... ON scope. I have one, but, still don't know how to use it.
On the hv probe, I have one, but, didn't think of checking hv on this set. If I had, I might have been elnlightenned that something else was going on.
Stupid me..................
One of my sprague orange drops had also gone bad, and, I re replaced it two days ago.
It was quite leaky.
Hmmmmmmmmmmmmmm.
Bill Cahill

I also had tubes failing almost everywhere, and, apparently had missed one while originally working on set.

Reason for all those years. Life. I was working in a high pressure job.
At that time my gull bladder failed, and, I had major health issues for a year while they were messing around trying to find the problem,a dn, kept telling me that though it had a dark spot, men don't get bad gull bladders.
8 months, and, one week later the surgeon removed it.
It took a year to recover from that.
16 years ago I had to have surgery for chataracts in both eyes.
Then 15 years ago I had to have laser surger for glaucoma.
Then, I lost my job, and, was doing volunteer work.
Eight years ago volunteer work ended, and, I started getting hip problems.
I'm now on forced retirement.
Oh, boy, has this been a fun life!
Not complainnig, but, just felt you needed to know why this project, and, manny others were put on back burner for years.
Bill Cahill

[Bill Cahill]

Well, my luck ran out.
I re replaced the two electroytics.
Started trying set. For a brief moment I saw a picture come on. I had full vertical height, and, width was nearly full. I had variac set at almost 90 volts.
Suddenly, I heard a Pop, and, raster went out. Set started making noises I didn't like.
I shut it down, and, examined parts. Couldn't find anything.
I slowly brought variac back up.
Iwas getting very low B+ at that point.
I heard another pop, and, sizzling. I quickly turned it off.
I smelled around, and, didn't like odor.
I put chassis back on its' bottom, and, pulled hv cage. Instantly I was rewarded with some smoke, and, the acrid smell of burnt transformer.
The smoke stopped, and, I smelled around. The flyback is toast.
It is history!
Now, my entire house smells like a burned transformer.
Flyback is cooked!
Oh, 589^%T##%#T%T$#!!!

Anybody got a good flyback for this set?
Until then, I've pulled all tubes out.
It's a special transformer.
Bill Cahill

[Spinning Head]

Sorry to hear that; major bummer.

[Bill Cahill]

Thanks. I made a confirmation by semtlling around, again, and, flyback is definately it. To confirm it I put my ohmmeter accross hv winding. It is bunred open.
Apparently, that's why the flyback was getting hot yesterday.
I guess that permanently ends that project!!!!
My house still smells like buned transformer.
Bill Cahill