I got this ts18 chassis and no pic at all no matter what I do and the sound I get very little at max volume, could this be a result of a bad 1n34 diode? I adjusted the adjusters along the IF tubes but put them back when It made no difference for sound or a hint of a pic.

Could be. Or a bad tube or an open IF transformer or problem with the video amp.

Where is the IF transformer? All tubes check perfect. The video amp would give very low audio?

There are several IF transformers - they are what you referred to as the 'adjusters'. The audio is pulled off right after the video amp.

There are several dog bone type capacitors in this chassis, can they be replaced with Micas of the same value or just use ceramic disc. There is 100pf and 250pf in the verticle section. I know the price for Micas are more then disc but will they perform the same.

Those tubular ceramic capacitors are very stable and reliable. Much better than cheapo ceramic disc caps. I wouldn't replace them until you've eliminated any other source of trouble. If you do, replace with either mica or C0G type ceramic.

Ok this one is for bandersen , still have very little audio and no picture at all so I was wondering if having 2 .001 ceramic caps in the horiz circuit rather then the right ones would be responsible for the loss of video and audio. These caps came with the chassis.

No they wouldn't. Could be the diode you asked about earlier or issues with the tuner or IF.

Also, these sets were preset to receive only eight out of 12 channels. Could be you are feeding it one it wasn't preset for. How are you feeding a signal into it? Can you try other channels ?

This chassis I had bought and was listed as a working chassis but you know things have to be gone over because it didn't work but is has been recapped and looks ok. So I'm using the same signal as I use with my other Motorola tabletops. And I have it on channel 3 with the matching transformer and tried another thinking the trans was bad but no different. I kind of did an audible check on those if transformers and I used a digital Volt ohm diode check and they all beeped as if they were not open that's really the only way I thought was a good way to check them.

Your set might not be adjusted to receive channel 3. Can you feed it a signal on channel 4 ?

Well I changed it to 4 and that channel don't even have Alittle sound , only 3. So I may have to adjust all those trans and hope I can get it, of course after I try another 1n34 that I got from another chassis ? I have the tv signal hooked to the ant screws on the back.

Ok well I kind of used wire clips with another 1n34 no difference. So I don't know but am I now to screw around with these IF adjustments until I get something or is there something I should watch out for?

Ok well I kind of used wire clips with another 1n34 no difference. So I don't know but am I now to screw around with these IF adjustments until I get something or is there something I should watch out for?
Dude,
The video IF adjustments are factory pre-set to give the correct video bandpass, and the settings are hyper-critical. They should never, ever be screwed with. If you do, you'll introduce ringing and/or smearing-out of fine detail in the pic that's next to impossible to correct without a full instrument alignment.
You can generally get away with tweaking the sound IFs a bit, but never the videos

Any ones I did move I put right back so I'm at a stand still as to why the sound is low and no video.

:worried:Yikes.

Have you checked tube bias voltages against the schematic, swapped RF/IF tubes cleaned sockets, checked for open coils etc.?

I would never, ever turn the IF transformers, unless you know that somebody had previously turned them. And then, you had best be prepared for a full sweep alignment. This set sounds like it needs a careful and systematic troubleshooting.

Did swap tubes and I do think someone played with the transformers as there is shiny spots that show where the screws were. I use a digital vom in diode test to see if there were any opens in the coils and checked the connections of the coils and they are in place.

Well I think what's next is checking resistors in the If section because I'm sure if one resistor in the right place along the IF is bad I'll get the same result. I do have sound on channel 3 so it's not that far off and when I say turning the IF trans I meant half turn then right back I do know better then to turn them at random and then a full alignment will be needed and I don't want that to be the case since I don't have the means to do that correctly .

You know, for a reasonably small investment, you could have yourself a B&K 1077 Analyst. Those things come in really handy when you get into these "I don't know where I've lost my signal" situations.

One thing that comes to mind: you put a new diode in parallel with the original detector (which confirms it ain't open), but did you test the resistance of the old diode both directions to confirm it is not shorted?

If it's shorted it could explain both symptoms you have.

Tuning RF/IF coils should always wait until it's last resort time, and all components have been tested.

Tuning RF/IF coils should always wait until it's last resort time, and all components have been tested.
And even then, turning of the video IFs should never happen unless one is equipped with a sweep genny and 'scope and knows how to do alignment, AND there's clear-cut evidence of misalignment (ringing and/or smearing of fine detail in the pic), and subbing the IF tubes doesn't fix it.

And even then, turning of the video IFs should never happen unless one is equipped with a sweep genny and 'scope and knows how to do alignment, AND there's clear-cut evidence of misalignment (ringing and/or smearing of fine detail in the pic), and subbing the IF tubes doesn't fix it.

Agreed. Though some service prints give data for a sweep-less peaking alignment using a simple sine-wave generator, some adjustments like traps are meant to be peaked to a frequency and can be set the same way.

I remember one guy here who properly aligned a Dumont by eye....I would not try or recomend that, but MAN was it ever impressive....

I clipped one leg of the diode and checked it for shorts and got no beep either way on that 1n34. Would I even get an ohms reading from that diode? I did check voltages on the 12at7 and pin 1 128 Vic and says it should be 107 Vic , pin 4 41 vac, 38 vac pin 5 41 vac, I get no ac except 236 Vdc , and pin 6 is to be 215 Vdc, I get- 1.0 Vdc . V6 a 6au6 pin 5 215 Vdc I get 87 Vdc and pin 6 232 Vdc I get 171 Vdc. It's wacky... Well I check the 1n34 for any ohms and got nothing either side with one leg off and also check the spare I got and that one had no ohms either.

I wonder if this is something to do with the contrast control being as it acts like a tuner to much one way and sound and pic is gone. The pot measures good but there are several caps on this pot...

You need a meter that has a diode check setting. It won't conduct unless it is forward biased, and then it will conduct in one direction only if it is good.

I do have a digital diode check and get nothing either side of it including ohms nothing either side of the diode.

Sounds dead to me. PM me your address again and I can drop a good one in the mail for you.

are these 1n34 diodes supposed to give a reading in ohms or diode check because i have another one from another set and get nothing from that one either unless that second one i got is bad as well. i know some diodes wont get readings so i dont know about these. the replacements are nte109 IIRC ?

I don't know what meter you are using, but my Fluke gives me the voltage drop of the diode. For example, a germanium diode will read approx 0.3v when forward biased and OL (over limit) when reverse biased. If you use an analog VOM, it will give a resistance reading when forward biased and read infinity when reverse biased.

i have a new dvom and is very sensitive and has diode check along with resistance and i get absolutely no reading whatsoever either side of either diode, i thought i would get something, well i guess if they were good and i do trust my dvom but i get nothing,lol...

I am dropping 6 of them in the mail to you tomorrow. I tested them good. Let's see how your meter tests them.

Ok upon taking the old 1n34 diode out I made sure of where the line is on the diode and put the new one with the line in the same position, facing down so I now have strong loud and super clear audio but no picture although I have several caps coming to change yet because it looks like a possible vert and horiz problem. But I reversed the diode and tried it that way and it was the same don't know what the difference is but maybe I would see it once I get video. Reason I reveresed the diode because I read a thread on another site that indicated that these diodes sometimes won't work unless they are reveresed from the original ones position. So I put the diode back the same way the old one came out then finish up with the other areas in question then see the result.

Ok well I'm stumped , put the diode, 1n34, in and changed the caps I had to and I have plenty of sound but not a picture to speak of, not even a hint of one. If the sound comes off of the video output tube then I would think I'm missing something in the video put section. Any good hints I could follow?

Do you have a raster ? Check the contrast control.

I have a raster and the contrast control really don't make much difference as far as showing a hint of a pic.

I checked the IF tube resistances and all were near perfect except for v3 and v4 both 2-7 both tubes should be 82 ohms on the same 2 pins but I'm getting 208 ohms on v4 and v3 144 ohms. I checked the resistances on v 1 to v 6 the video output tube. If the audio comes off the video out tube so strong and clear then the video should be there somewhere.

Video is coupled to the CRT cathode through a .05 mfd cap. That cap could be bad or there's a bad connection to the CRT cathode (pin 2).

Also, the brightness control sets the voltage on the cathode. Is the brightness control working ?

Well I was hoping that was it but took one leg off that cap and it's not a .05 but rather .047 that should be ok and it tested perfect. Also checked the cathode wire from the 470 resistor up to the crt and that's good to. The brightness control works ok.

The voltages are perfect at the video output tube.

If it's not too difficult, try reversing the 1N34 end for end. I know some of the older diodes were marked opposite from a modern one.

Ok it was very difficult to even get a picture at all but lucky I did because the coil at the ant input was burned and no matter what I adjusted, the IF coils I could not get it clear picture. So I changed that coil and all the adjusting paid off in the long run because here is the result after changing the coil. Sorry it loaded this way.

Here is the coil, don't know what happened so maybe someone slipped and shorted it out. Note the wax got hot.