Vintage Johnson Viking II CDC Civil defense Transmitter shorted power supply troubleshooting Part 2

Part 2. In this video I am testing the transmitters power transformers and DC supplies. The 350vdc power supply has a short. Tracing it became quite a feat. After a few hours of chasing my tail around, I discovered the short was a simple fix. Had I performed a better initial inspection, this would have been discovered, saving me time + frustration. Good to keep in mind. If someone else has been in there before you, there may be some surprises awaiting! I have the power supplies tested. Next step will be rebuilding the audio section. Change the interstage transformer, wax caps, bad resistors, etc. This will be covered in part 3. If you want to support D-lab, see: / dlab_electronics

[@letsreasonthisout2898]

"This will probably remove the short..."....ok, THIS will probably remove the short..."...Ah ha....I found the short, this will remove it..."...🤣 I love how Terry has zero hesitation to reveal his stumbles along the way to placing a GREAT transmitter back on the air. I have the CDC, and AB2RA worked with me to get it back in top "broadcast quality" audio. The CDC is an absolute gem of a transmitter, and is well worth putting back on the air for the AM nets...as is any Viking II. Love the passion Terry...keep them tubes glowing!

[@hobbiesrus]

Nice work, Terry. How frustrating!

[@WECB640]

I love these mystery repairs. 73 OM

[@voxpathfinder15r]

Thanks for posting this content, I don’t take your efforts to show us this stuff for granted

[@mackfisher4487]

Thanks for keeping those old rigs on the air, and supporting amateurs with your technical skills.

[@russellhltn1396]

Third time was a charm. Glad it was all it took.

[@tomk1tl39]

Your are an amazing troubleshooter . . .👍👍

[@jonpardue]

Good mystery to solve on this one! Way to stick with it.

[@LouinVB]

I have the same TENMA 72-1095 Variable Isolation Transformer Variac. Nice unit.

[@alexdeleon7135]

I knew this trilogy was going to suspenseful. Terry, your process of elimination is commendable. Not only is it logical, but it affirms the reason for the hourly fees that sometimes incur with having to perform detective work. Documenting your expedition also provides the owner proof for the necessary exploratory surgery; before assessment of parts, as well as reassembly. I am still flummoxed after watching part 1; as to why there is no copper shielding in this "factory built" Viking II. Is that something you've encountered before this case? I await part III with great eagerness.

[@neutralobservation9418]

Wow. Pretty cool.

[@mikefinn2101]

Great find Terry well done nice you showed all of this great learning experience thanks 73s wb7qxu

[@daviddahlgren9603]

Yes , I did go into my radio room and take a peek down into my Viking II . . . Since mine is not a CDC, it's less congested . Nice catch d-lab !

[@phillipalexander5389]

Your supposed to replace a couple of resistors. 🚜🚛✌️

[@HughYedda-y8i]

Schuster Ramp

[@neutralobservation9418]

Is this a "Barn Find" CDC??

[@d-labelectronics]

Nope, a customer unit. Looks like a barn find.

[@F_Tim1961]

@@d-labelectronics here's an idea that the Customer can consider. THere are a plethora of AD 9850 and 51 DDC oscillators available that will tune the entire ham band. THey can't drive the buffer amp that exists in this unit because they put out only 500 uW or so but as a sine wave . However with a single Transistor amp based on 3866 or similar this cam be brought up to 15 mW or so . l normally this will drive in place of a crystal. (easily) . Thus the whole analogue osc can be replaced by something stable and modern and with a rotary control. The Toroid king in FL sells such an amplifier for around twelve dollars un built. Even better is the concept of injecting a couple of watts of AM or DSB into the SSB in port that some Johnson Vikings have. THat's to say all the amplification past this port is linear. Possibly this model does not have that capacity.

[@charlesclark3840]

Why would they use non-insulated wire for those wires, where if they managed to touch the chassis they would short? It does not seem wise (says the know-nothing commenter who has never made a point to point wired anything).

[@d-labelectronics]

Normally the wire is a thicker gage, not as easily bent, Yes, I agree some insulative tubing would have been nice

[@zebschreiber7357]

It's not uncommon in older stuff. But I just fixed a Kenwood ts-529s that had an insulated wire rubbed through the insulation making contact with a terminal on a pot and wouldn't transmit. Couldn't believe that it rubbed through the insulation on that radio. Maybe it was in a vehicle at some point? Who knows. It also had a cold solder on the sidetone board. That's what I was looking at when I spotted the wire.