July 4, 2019 at 11:44 am #11639
The Arvin 542T was designed to be manufactured and sold as an inexpensive radio for young families in the early 1950s. It’s a 4-tube superhet without an IF amplifier stage (12SA7/12SQ7/50A5/35Z5) and requires an external antenna. The 35Z5 operates with no dial lamp (with a reduced filament life?). Figure 1 shows the top of the chassis.
Figure 2 shows the original wiring. In keeping with my personal restoration philosophy of trying to return a radio to its factory look and performance, when I recapped the set I restuffed the wax paper capacitors using the simple technique of slitting them lengthwise, inserting new poly caps, and sealing the ends with brown hot glue. They’re reinstalled in the set with the slit oriented on the back side as shown in Figure 3.
I tried a different technique for restuffing the electrolytic filter cap and it worked quite well. Normally I would unsolder the wires, remove the cap from under the chassis, melt out the insides with a heat gun, put new electrolytics in the old paper tube with new wires, and replace the whole thing. This time, I tried leaving the original wires in place and cutting them off close to the old paper tube. I then attached the new electrolytics to the old wires under the chassis, inserted them in the original paper tube, secured them with a dab of hot glue, stuffed in some bits of paper towel, sealed the end with brown hot glue, and secured the mounting tab to the chassis. The sequence is shown in Figures 4, 5 and 6. The technique preserves the look of the old wiring.
I replaced the out of tolerance resistors with new carbon units, cleaned and lubricated the controls, and aligned the circuits. Next I’ll present some pictures of the cabinet.
Attachments:July 5, 2019 at 1:47 pm #11646Jean MarcotteForum Participant
Gary, why slit the wax paper capacitors? They are easy to empty using the heat gun and you can clean the outside at the same time when the wax melts. When I restuff them I use wax instead of glue for more original look. Nice job on that little Arvin.
JeanJuly 5, 2019 at 3:29 pm #11647
Hi Jean – thanks. I seem to switch back and forth between the two stuffing techniques depending mostly on the value of the radio. The technique of slitting the capacitors open is very fast, no mess, and, for some restorations, retains the original ‘dirty’ look of the original cap. For my more valuable radios, I use your technique and reuse the original wax on the ends. I leave the guts from the old caps in a bag inside the radio for posterity.
For the filter cap in this radio, I used your technique to melt out the insides after I had cut it off from the original wiring. But then I resorted to brown hot glue on the end instead of replacing the original wax!
BTW, do you have a way to replicate the integrated ceramic package containing the resistors and coupling capacitor between the first audio and output stage? Looking closely at the pictures, you will see that I had to replace it with discreet components. They often are good, but this one was the exception.
GaryJuly 8, 2019 at 6:37 am #11662Jean MarcotteForum Participant
Hi Gary, I never encountered a problem with those ceramic “couplates” I think they call them. I was lucky to find a bunch of them NOS in an auction but there are so many different kinds, mostly for TV use. I suppose a repro would be possible using modern ceramic discs and resistors. Another great challenge.I have never tried molding parts yet. Still a lot to learn.
JeanJuly 8, 2019 at 12:16 pm #11666
Sure is a lot out there – I’m still.learning!. Am toying with the idea of using SMT parts to fabricate a couplate if I ever run into another bad one.
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