COLUMBUS model 90 Made in New Zealand in 1945. Part 1 

Interesting repair so far 👍 Those roosters though 🤣

That is a beast Don, it would have been expensive set to buy. Good that Ron was able to supply a new transformer so quickly, hopefully mounting it 90 degrees from original doesn't create any problems. Steve is a good bloke, I have had quite a bit of interaction with him, he has been a bit quiet lately YT wise. The field coil resistance does sound a bit low, I wonder if that caused the TX to overheat? I will be happy to rewind it if that is the case, Bermuda sounds nice this time of year 😉😄

Nice start, Don (and thanks for making me blush - there are plenty of things I don't know about Kiwi radios...). Replacing those transformers can be a frustrating task, due to the way the wiring is packed in. They were never wax-impregnated when Radio Corp made them, and I think one of the failure modes is the windings loosening up, then humming and vibrating, leading to shorts and then eventual failure. And it sounds like the speaker field coil has shorted - it should be 1500 ohms. Possibly taken out by the failing power TX. They can be re-wound, although I don't remember the wire gauge offhand. Something fine. Those 10" Radio Corp speakers sound fabulous, so it is definitely worth fixing. I'll see if I have a spare field coil here - although I don't think so. Not intact, anyway. Oh, and those soldered-in upright can caps will be tropicalised 0.1uF paper caps - they can be easily desoldered from the holder and then replaced with something that isn't oily and sticky. The nice thing with them (and possibly why they were done that way) is that they provide a solid tie point in the chassis. And I suspect that Solar cap is a replacement - they either made their own caps (which will be labelled Radio Corp NZ) or they typically used Ducon and Hunts in that era (although in the post-war shortages, they (like everyone) used what they could get). Their own caps were being used in military contracts through the war as well, and can be found in military ZC1 transceivers, among other sets. And that set should have 2 dial lights, someone has removed one - and yes, there is a very low resistance often used in-line with the dial lights, or a tap on the 6.3V winding - reducing the dial light voltage by about 10% vastly improved lamp life. I'm very much looking forward to part 2 🙂 Cheers, Steve

Excellent start Don. love the side kick to Dave Tipton I'm sure he would help you if you needed it. Come on on you viewers give a thumbs up it helps promote these selective channels we all love about vintage radio & amps.

Looks like a nice start. I'm glad Steve came to the rescue. I just subscribed to his channel, but as it's past my bedtime, I'll be checking it out in the morning. Looking forward to the next installment......

You certainly have a lively neighborhood, Don, with the roosters and motorbikes and all!😉

Sorry to read about the field coil Don-a collab with Dave beckons I think, as various Columbus radio parts crisscross Australia! I can't imagine a HT short causing a failure of the transformer primary AND the field coil, so I'd be putting them down to isolated failures, but no doubt you'll check all that. Great to see you back after your break.

AT THE 27:52 MARK, LIKE SHANGO 066 WOULD SAY **BAKED!!**

Good work, Don! Power transformer primary failures are relatively rare, in my experience. Usually it’s the HV (aka HT) secondary that goes. Glad you got a replacement. You’re on your way. Funny to see a radio on your or David Tipton’s channel without an Aussie “stationized” dial. Just markings in kilohertz….what a concept! ;-)

Really enjoyed this one and looking forward to seeing the next instalment. Thank you so much for your kindness in sharing

Thanx so much for doing this Don - I wish I had one to play with/fix. Re. the transformer, if the laminations are the same size as the original, it should be possible to use the bells off the old one (after cleaning the soot out first) to make the Philips one look a bit more original. Also, that bare wire trapped between the bell & the laminations would likely connect to an electrostatic shield between the primary & first secondary. It would naturally be earthed.

The Can below the magic eye is an inductor part of the negative feedback tone control circuit. The field coil is around 1500 ohms. Beware doing an IF alignment, these Radios had a wide IF bandwidth and the description of the lineup is in the manual. These Radios had Jansen designed electrodynamic speakers and together with the wide IF and negative feedback tone control, they sound fantastic for AM.

Lookin really good from the USA Donnie Boy! Good thing you had some backup from Perth.😊

I REALLY enjoy 😉 your radio videos 📹. I thought the "moo" sound was your desoldering iron or something 🤔. Your friend, Jeff.

Nice work Don, so glad you also managed to find an original nob to replace the missing one. Good luck with part two, I'm sure you will concor this beast as it looks like a pretty good Looking one aswell. Cheers.

Crispy.

Love the Roosters

Great work. This was the radio equivalent of a heart transplant. Well done.

! Good thing NZ is full of spare knobs Looking good Don ❤😂🎉😊😊😊

3:40 A New Zealand radio? *No chups!* LOL😁

34:00 Careful of the censors, Don! Hearing *fowl* language here! LOL😁

Hi Don, Nice to see you back. the electrolytics may be PCB filled. the fluid has a fresh odor and is somewhat sticky. the direction of the laminations probably should match the old transformer to reduce any hum that may be induced. Rich

WOW !! That primary looks horrible !!! I wonder what happened. Maybe there was a storm, lightning hit the mains and just destroyed the transformer ?

Possibilities are: Primary shorted to ground, Secondary winding's shorted and Rectifier Tube shorted.

Take care, that electrolytic may retain hundreds of volts hours later. It happened to me once a long time ago. I dropped the chassis when it bit me!

FYI: The ship logo is the Santa Maria, Christopher Columbus's ship. The story goes that William Marks, a Russian émigré escaping the communist rule in the mid 1920's, wanted to go to America, but ended up in New Zealand (there is a chapter in my book on Radio Corp NZ on this). The brand name was a tribute to his long-held dream, although he later travelled there buying parts and hiring staff and was said to have told his family that he was glad that fate had sent him to New Zealand in the end. The brand was actually originally used for exports to Australia (10 years before this set was made) - but they ceased exports in 1937, around the same time they set up Columbus Radio Centres across New Zealand, to retail the brand here. Your set wouldn't have been retailed there. Do you know its history? I'd guess it was most likely dragged across by a Kiwi moving or retiring to a warmer climate...

The forensic investigation of the old transformer shows how badly burnt up it got! The replacement one was checked for output and voltage. She's good! Solar caps usually are crap by now! I don't have a China made tester like that as it's not made to check a capacitor's ability to handle much higher voltages than the tester puts out. Must replace all wax paper and the electrolytic caps. Bury them in the bin. You're doing great Don and love the progress made so far. Steve from IL in the USA

6:40 Tubes out of position? It was likely difficult to put them back in their respective sockets, considering that they were hard up against one wall of the cabinet.

it's not shazzi. it's chassis not tchassis. as in champagne or chamois