[Eliot Ness]

It will never be perfect - or original - but I feel this has turned out well.

Maybe not perfect or original, but the grille turned out great and you literally saved this radio from the trash.  What a great story you'll have when finished with this beauty from the 1936 Zenith lineup. 

[Paul Philco322]

For a curbside find right! It was only original when 1st bot, maybe not even perfect then, always a bad day or two on the ol' assembly line. Nice work, good rescue.

Paul

[EdHolland]

Thanks again. I agree this one was a really fortunate find, and very close to being a total loss. It seemed very unpromising at first, especially while lying there all sad at the kerbside waiting for the end. But the more I looked, and have worked on it, the more I could see it being a success. Being not so familiar with Zenith, It was a surprise to find that this is quite a collectable radio, and fun to learn about something new.

John - Yes, I do enjoy the story of saving things like this, and in some ways having that behind it makes it a lot more appealing to me than if I'd found or bought a "pristine" working set. There's a lot of value in the journey.

[mikethedruid]

I absolutely agree, Ed. I never buy sets which have already been "restored." That is not my hobby, never has been. Ever since I was a kid it is the thrill of taking an old set which no longer works, diagnosing the problem, and bringing it back to life. Back in the old days I could often find these sets actually being thrown away on trash day, or be given them by friends and neighbors who knew of my hobby. So, still today, I don't buy sets somebody has already restored. I buy the ones which are sold for "parts or restoration." The sad thing is, some people see the prices the restored sets are selling for, and set the price for their unrestored set the same. It gets maddening.

[klondike98]

I'm like you mike, I like to take the unrestored, sometimes basket case, radios and make them work and look decent again. Sometimes they come out looking and working really good, other times they are just better than they were when I started.

[MrFixr55]

Great Thread. Ed, great job on the cabinet. I am not good at wood but love fixing electronics.

Like Mike the Druid and most on this forum, I learned electronics as a kid from books and from radios and TVs given to me by neighbors or from that great German-Italian store Offthestreetini. I parlayed that and my formal college education in Clinical Lab Technology into a 41 year career as a Field Engineer, 39 with a major manufacturer of Automated Laboratory instrumentation. So this hobby prepared me for a great career

[EdHolland]

Lots of other odd-jobs in the way between me and the radio bench this weekend, but I did make a little progress on the chassis. One thing I haven't done in previous restorations is restuffing the paper caps, but for some reason this radio seemed to inspire me to make the effort. That required a trip to the hardware store to buy more hot-glue sticks, but it is only a 5 minute walk away. Then, I had to repair the heat gun - it was always curious that the only setting was "Flaming hot" and the reason was that the temperature dial on the back of the case had broken. The 3" diameter wheel operates a small pcb mount potentiometer via a flimsy plastic spindle. Reglued the spindle back on to the wheel and we were away.

After those diversions, the first two caps were removed, deconstructed, and new film caps placed inside the old paper tubes. In doing this, I realised that several of the caps are replacements, and that they have been tacked in to place in haphazard fashion. Two of the solder joints just fell apart, with component wires barely tacked on to their the terminals.

I hope to make much more progress next weekend. This set shouldn't take all that long to recap.

Ed

[Arran]

Ed;
  If you mean those ones that look like Cornell-Dubilier "Tiger" capacitors, I'm not familiar with whom supplied Brand Z with their paper caps, but if those are replacements I think they may be pre war ones. Philco seemed to like Sprague, I think when they moved away from the Bakelite block style to the tubular ones, that was whom produced them.
Regards
Arran

[EdHolland]

Arran, yes, it was the "Tiger" types to which I was referring. At least one of these was lazily tacked in (fell off its connection point) and what looks to be a more modern sleeving had been used to insulate the wire lead. In other locations, there are still Zenith branded caps, presumaby factory originals. It's all part of the radio's story.

[EdHolland]

Nothing really picture worthy, but I restuffed all the paper caps today. The chassis looks almost as I found it

On the way round, I found a number of repairs that were badly soldered or just tacked-on, and I have one "mystery cap" that has both ends connected to terminals that eventually lead to the chassis. That mystery ought to be easy enough to solve, as there is only one 0.05 uF capacitor that connects into the front end circuits.

On to the electrolytics next weekend!

[EdHolland]

The auction site turned up a very nice condition speaker of the correct type for this radio. Initial bidding was around the $90 mark, reasonable shipping and all was quiet until the last minutes and seconds. I declined to follow the frenzy - the final sale price was $255!

I'll admit that the unit appeared to be in very good condition, but this was far too rich for my blood and went well over the budget I had decided. If the rest of the radio was in more original shape (knobs, tube shields, grill cloth yadda, yadda,) it might have made sense, especially if I were looking to sell it on.

Meanwhile, I have something that will work.

/Ed

[EdHolland]

Some circuit sleuthing today. The cap which had both ends grounded was the first thing on the list. Found on the circuit diagram C2 is the only 0.05 uF component associated with the frequency changer & antenna coils. One end should be grounded. Check. At the other end, a connection to the secondary of the antenna transformer. Check. Connection also to the bandswitch. Check. But... there was a wire leading from the bandswitch back to the chassis. This looked like an addition - poorly soldered on top of another solder spot. For now I have lifted, but not removed the wire.

Nothing more to do there until live testing, so it was on to the PSU filters. The first, 8 + 8 uF was a Mallory replacement, with colour coded flying leads. I found that the top of the can popped off, and after some work with the heat gun, the internals, set in pitch, were released. I snipped off the wires, and resoldered these to new 450V caps, heat shrink over the connections, and threaded everything back through in to the can, including the grommet through which the wires passed originally. The top of the can popped back in to place, and the result is very satisfactory. There was a bit of a struggle making room in the "eyes' of the solder tags for the wires to pass through. Just one last cap to tackle.

More, I hope, tomorrow,

Ed

[EdHolland]

A little more today. The 10 uf cap in the tail of the power supply was originally a large Dublier can, which had been replaced by a Mallory axial soldered directly to the Candohm.

I removed the large can from the chassis, cut it open and removed the cardboard cartridge which filled it. This thing was overkill for a filter on the negative bias end of the PSU - 10 uf at 600V! Zenith service sheet calls for a 10 uf at 25 V... I added long cloth covered wires to a 10 uf 450V electrolytic which will do the job nicely, and hot-glued this into the lower part of the casing. I made a new rubber grommet for the wire exit point. The cut edges of the can matched very nicely after facing them with a large flat file. A card sleeve was made and glued in to the upper piece, with about 1/2" extending from the open edge. Once the glue had dried, I added glue to the lower part of the can and the card, and placed it over he other part of the can containing the new cap. t looks good

[EdHolland]

I made up a harness for the speaker, sorted out what was transformer and field coil from the wires on the speaker and spliced the two together. At the other end, a 5 pin plug was connected. I made some last checks and got ready for testing. The usual procedure - no tubes, "dim bulb" tester was an instant pass. I checked voltages on the transformer secondary and all was well. No noises save a smooth and very feint hum. Then all the valves/tubes except the rectifier. The bulb lit up, then faded to very dim - All good. After that I put the 5Y3 in it's socket, with a meter connected to B+ and applied power.. Voltage came up, and there were some sputtering sounds from the loudspeaker - Life! Crackly bit there. Quite a bit of crackling. More crackling if the bandswitch was operated. All good signs. Although there was not an antenna connected at this point, I tried tuning on the MW band anyway, and found a station. Excellent.

The terrible garage antenna was hooked up and more stations could be found, but there was still a lot of intermittent crackling and not much volume at all. I tried powering without the bulb, but although there was static, no stations resulted. There was also still the issue of crackling, so I turned it off, and removed each valve, cleaned pins and sockets, and cleaned the bandswitch. Things came back better, but still crackly, and still better on reduced power, so I turned the chassis over, and started poking carefully with an insulated stick to see if the crackle could be provoked. As various parts were prodded, there was not much response, but all of a sudden, it went dead...

OK, time to consult the voltage chart... and I already had a suspicion which turned out to be valid. The 11 KOhm section of the candohm, which is the bulk of the resistance between the HT and the rest of the chain had opened. Temporarily, I added a 1W, 12K resistor across the tags, and life was restored. After cleaning the bandswitch, there was more life evident on the SW bands, and I caught snippets of a broadcast station, and the WWV Time Signal - I think 10 MHz, but without the dial, hard to say.

Last of all, the signal generator was tuned up to 252.5 KHz and the IF transformers were aligned. They were quite a bit off-peak, and this obviously brought sensitivity up considerably.

So, a good day on the radio bench

[mikethedruid]

So far so good, great progress ! Now time for the dial, and a thorough alignment. Keep up the good work !