1961 Coronado Capri
 

The zenith I worked on earlier in the year has a bad CRT, so I tucked that away and am going to try to get this one running 1st. Its a 17"B&W, chassis #TV2-9402H. Sams set 553, folder 1. I'm still a rookie at this so please bear with me.
This is full of bumble bees, but there arent a terrible amount of parts in it. Its a hot chassis set. Im adding a few pictures and have a few questions;
1. The crt back side is peeling. Is this going to be an issue and is there anything I can do about it? Hot chassis is one of my concerns with that.
2. The flyback has one crack. The pic looks like 2 but there is only the one. Should this be coated somehow or should I just go ahead and try it after I recap? I did try a slow power up with no results except squeeling from the speaker.
3. If you notice anything else on the chassis feel free to comment. It has a 20W resistor way over tolerance so I know that needs replacing too. The CRT tests good, at least with the tester I bought. I do have a schematic. I also have isolation transformer. I can add pics of if needed. Thanks!

It's a Wells-Gardner built set. A decent set, for an inexpensive model.
The 20 watt resistor is probably OK. The resistance is probably high, because the set doesn't have a UHF tuner. It's a heater dropping resistor. It's either good or bad, they don't increase in value. You mentioned, the tubes light!
I would be more concerned about the high-value electrolytic, as the set doesn't use a voltage doubler. Then you could start recapping in stages.

Wow, that is one of the cheapest built portables I've seen....I'm surprised that it only seems to use three sections of lytic.

You can clean the flaking aquadag off the back of the CRT (taking note of what the original border of it was), mask the areas it does not belong off, and re-coat it with "Slip-Plate" (spelling?) or "Areodag".

I have not had arcing/corona issues with cracked tires in monochrome TV so I usually get the set working before worrying about the tire.....YMMV.

I'm glad to hear it is a somewhat decent quality. The 20W tests at 330 and is supposed to be 36 ohms. this wont matter? Yes, it has a 200 and a 250uf electro's. They'll be one of the first things replaced. I think they will both be replaced with 220's unless thats a problem.
Can the chassis safely be started without the CRT, speaker, etc not hooked up? Too test voltages. The less times I have to pull it apart the safer the crt neck will be.
Thank you for the reply.

I have a couple coronado radio's too. Its a common brand here. I've seen radios that had more parts than this TV.

Could I slip a piece of intertube between the tube and metal to keep it from arching? At least until its working. Sorry but I cobble a lot of old cars and cant help but think like that LOL

That resistance can't be that high! The tubes wouldn't light up. You can run the set without the CRT, but the yoke has to be connected. 220's are probably enough capacitance. :thmbsp:

What does the Sams say about the resistor ??
Looks like it goes to the rectifier. If so normally its
a 5.6 ohm 5 watt fusable or there abouts. Also
its a wire wound & I have NEVER seen one change value
only open. If it is open change the rectifier too.

For testing you can pull the chassis & yoke then put
the HV lead in a glass jar. OR get a test CRT. OR get
test sockets that plug in between the tube & socket.

The dag thats flaking needs to be fixed. It acts as one side
of a cap along with the inside coating & needs to be grounded.

Last thought is BEFORE a recap get a picture on the set.
Many reasons why........

73 Zeno:smoke:

He did say he brought it up on a variac and only got squealing from the speaker.....If it powers up like that he will have to replace caps to get a picture on it....Maybe go a few caps at a time and test the set after each 1-3 caps, but if it ain't showing a picture with all those bad plastic caps in it there is NO way it will get better with all those caps there.

Im including a pic of that part of the schematic. It has a 5.6 ohm fuseable installed (R57) and that is fine. Its the other one (R58) that tests so high. I circled them in red.

Thanks again for the advise. I will recoat the CRT, clean sockets and tubes, put in new electros and see what happens. (maybe other things that I spot) All the tubes did light up when I had it powered, but several were bad so I will replace those too. I guess I will just put it all back together before trying it. It wasnt t too bad to take out, I just worry about the neck.

Edit: electric M, I posted before seeing your last post. I dont mind switching the caps if I need too. They are all bumble bees so I figured there may be bad ones anyway.

You could probably get away with gluing aluminum foil to the glass to replace the flaking stuff. Avoid the high voltage connection and the yoke area. And be sure the foil is connected to the set's ground.
http://www.videokarma.org/attachment...1&d=1449335140

You'll need to replace the usual wax caps, bumblebees and electrolytics.

Being a rookie on tv's, I probably better not try the tin foil as I may damage something or do it wrong. I painted for a living many years and understand that. Is this the correct slip plate product? There are a couple varieties and this one has a G on the end. http://www.ebay.com/itm/SLIP-PLATE-3...4AAOSwnipWYodd

At the very least, I'll test the bumble bees and replace the bad ones, after it being suggested now a couple times. Maybe I'll just do them all as its good experience anyways. Thanks!

Don't bother testing them, they're all bad.

I forgot to mention that you have to jumper the CRT socket, pins 1&12 to get the tubes to light, without the CRT in the circuit.
Regarding the heater dropping resistor, what kind of meter are you using?
The reading is off, by a factor of 10. The resistor looks original, with a W-G part number. As before, the tubes wouldn't lite, if the resistor is 330 ohms, instead of 33 to 36 ohms.

It may be an error in Sams. If its a say 33 ohm & you add
a zero its a 330 ohm..........

For now just check for APX 95 vac on pin 7 of tube V7.
You do not want to put a 33 ohm in if its a 330 ohm.
NOT good for the filaments............

Why get a pix first ?
1) to be sure you got a good CRT. Even if it tests good it still can be bad
& visa versa.
2) check to see that all MAJOR parts are OK. Even 40 yrs ago
you couldnt get some of this stuff.
3) you learn by troubleshooting NOT shot-gunning
4)re-caps need to be done a few at a time followed by a test.
If you do something wrong its easier to find if you just gotta
look at a few things. Nothing worse than finding a self induced
problem. Sends techs running if its "been somewhere else"
& never fixed. And you never get the truth out of the
customer !!

good luck
Zeno:smoke:

This works great for coating the CRT.

http://www.amazon.com/MG-Chemicals-C...+Chemicals+838

Tinfoil can come loose and short out the chassis.

The flyback isn't bad enough that I would mess with it, you risk more damage by tinkering with it.

33 or 36ohms has to be right! 36 ohmsX 600ma=21.6 drop. 21.6+95=117volts, approx. :thmbsp:

Wow, thanks all for the suggestions and the web link. I'll digest it overnight and try to answer as well as I can tomorrow. I'll try to read that 33/330? resistor outside in the sunlight too as it is faded. Again, thank you.

You are right. Over my schematic reading, I realized that publications from SAMS are often wrong. So now I am wary of what there are sometimes in the schemas. nothing better than a regular of repair of TVs to give you the real stuff, the real values of each piece...

I couldnt read the resistor well until I took pictures of it, then it shows them fairly well except for the last number. Top row A43(K or X) 402. Bottom is W.G.33 and the last one could be a 4. You may be correct about the sam being wrong. It tested at 356 this morning with a DVM. So for now Im guessing i should use it?
I'll order the coating product mentioned. Thanks again!

I looked the schematic in Beitmans. The heater string is the same as in Sams, showing a 36 ohm, 20 resistor. Ohm's law proves that the resistor has to be a value between 30 and 40 ohms, otherwise the tubes wouldn't lite at all.
Is your meter auto-ranging or it doesn't display the decimal point.
Your earlier posts, mentioned that the tubes lit, when you brought it up on line, but all you got was a squeal, which indicated possible bad electrolytics.

There's a quick & dirty way of measuring 'Gravel Gerties' of unknown value. :smoke: Crack it in two at the halfway point and measure the side that still has continuity, and multiply by two.

330 ohms at .6 amps would drop 198 volts

Great tip !! 40yrs in the biz & I never heard it. I tip
my hat 2 U.

Oh BTW we called them bricks up here.....

73 Zeno:smoke:

My meter has a 200 setting, then the next is 2000. It goes past the 200 setting (displays 1), and when I set it to 2000, it displays .356

Every tube lit up that I could see, with one in the can that I couldnt see.

I am lost about the cracking one in two idea.

OK, I dug out my analog meter and hooked a 330 ohm resistor to it and calibrated it to that. When I put the resistor in question on it, its reading about 68 with the analog meter. I didnt stop there. If I move the ends around the resistance changes... so I hooked it to the DVM and moved it around and it changes on that one too, (flexing the ends some) so there must be something wrong with the resistor. Should I just go ahead and get a new 36 ohm resistor and replace it? Then I'd know it was right.

That's only if the resistor is open and needs replacing, and you want to determine the original value. Obviously you don't want to cracka resistor that has continuity.

Don't feel bad bro. I had never heard of the 'aspirin trick' for stripping fine wire until recently.

There might be a loose internal connection in the resistor, or poor contact with the meter leads.
For now, just jumper in the 'lytics and see what the set will do. If the tubes light up OK, proceed further.
BTW, the HV rectifier is the only tube that is not part of the series string. It receives it's filament voltage from the winding on the flyback on a properly working horizontal output stage.

I will try the above after my tube replacements and parts arrive, and will post back. Thanks!

My aqua dag coating is supposed to arrive today so Ive been outside scraping the old coating off, which went pretty good. Almost all of it has been removed but I have a question. in the picture I am including, I circled a small amount of dag which is closest to the neck. There is some other type of coating, which doesnt look like dag, above the part circled. Is there an electric connection between the two areas or are they isolated from each other somehow? EDIT: Now that the sun broke from the clouds I can see that its on the inside of the tube so I answered my own question and feel dumb, LOL

The dag above the circle is INSIDE the CRT vacuum (so no need to try removing it). They would paint it inside the neck after the phosphor is applied and before aluminization (you can see some of the aluminization in areas where the dag brush did not completely coat the glass) to improve conduction in key places.

It went real well scraping, masking and coating it. I ended out scraping the whole thing clean. Now if the other parts would just arrive!

Success! I changed the electros, a reg cap and a resistor that were in areas I had to solder anyway, plus some tubes.

The bottom half is brighter than the top half (the picture was not moving when I took it). My brightness will go much higher when I turn that control. Volume sounds ok. I only ran it a couple minutes.

Will start recapping, but how do I get rid of the 2 parts on the screen? (There is a curtain reflection on the top half)

Also, can I safely pull the chassis back, laying it down, to get at the picture tube button hole to safely discharge it? Can anything on the chassis bite me when I do that? theres no other way to get at it as you can see.

Congrats fixmeplease ! ;).. now you need to continue.. ( for a better result, i would change all caps and resistor ( paper and wax if the TV has them..)Even if some caps look like good , sooner or later they will ... POUFFFF ! :D

Yes, all the bumble bees are gonna go bye bye.

The yoke also plugs into the chassis. Is that safe to touch? (off and unplugged of course) I dont want to get zapped. Plus my other questions. Thanks guys for all the help.

Turn it off and wait a minute or two...The can lytics (which are the only thing other than the CRT that can hold charge) should discharge in that time. Once the cans have had a chance to discharge themselves, pull the chassis (the yoke may need to come off with it) back until the HV cable is taught or the HV connector is easy to get at (whichever comes first), and discharge the CRT.

Is it safe to unplug the yoke? it has a tube like connection into the chassis and the wires are real short. That would leave the yoke on the CRT. Thanks!

If the yoke unplugs from the chassis, then is it perfectly safe to unplug (also safe if soldered on, but more of a pain to remove and reconnect properly).....Just don't power it up with the yoke disconnected....Pull the HO tube cap if it's series string heaters (if parallel pull the H and V output tubes) and you need to run it without the yoke.

If you have a test CRT and a spare yoke it will probably work safely with any similar era yoke.

Thanks! I'll give it a go again tomorrow, replacing a few caps at a time.

I got it recapped today, plus found several resistors out of tolerance, one by a lot, which was on the vert linearity control (a 3.9Meg that tested almost 10M). The TV has a mostly full screen picture now, great sound, but the vertical hold is hard to keep still, so I will have to deoxit that control and see if it helps. But Im done for today. I may have more questions but not tonight. Thanks!