40-201 now has power - Printable Version
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RE: 40-201 now has power - morzh - 12-29-2013
What was the voltage and what was the cap's voltage rating (the one that kept popping)?
RE: 40-201 now has power - Joeztech - 12-30-2013
codefox1;
Thanks for that input. This is only temporary and the chassis work and alignment is now finished. The only thing remaining on the chassis that is an issue is the dial cord and that can be done with it sitting in a normal horizontal plane. I plan to order some new dial cord and some springs to try on the main pulley. The springs I have on there now are from ball point pens and do not have enough tension. The cord slips on the shaft of the tuning knob and does not turn most of the time. Once in a while it will catch and tune the radio. It is frustrating. I have some leads on those parts.
Have fun!
Joe
RE: 40-201 now has power - Joeztech - 12-30-2013
morzh;
It was rated for 300VDC and was just not adequate for what the rectifier was delivering to it before all the rest of the tubes warmed up. The original electrolytic was rated at 250VDC. I was having trouble finding a 25mFd at the voltage that I was looking for from my usual sources. I finally realized that electrolytics have such broad tolerances for capacitance that finding a 25mFd was really not so important. The main thing is to find one that has plenty of voltage handling capability. When I started looking at 20mFd electrolytics there were many available at much higher voltages and I chose one of those. Physically it was no larger than the lesser rated one I had used. It appears that tubesandmore.com has lots of units to choose from at very good prices. I plan to continue ordering from them unless something prevents.
The fact that the B+ voltage is high there before the other tubes warm up may be an indication that the audio tubes in particular need to be checked for adequate emission. If they are weak and do not have normal current, that could contribute to the voltage being high. I need to check the nominal B+ again and see how much it is after warm-up. If it is still too high compared to the voltages indicated on the schematic, then more checking needs to be done.
Joe
RE: 40-201 now has power - Joeztech - 12-31-2013
Yesterday I picked up a chassis mount fuse holder from RS in Sherman, TX and used the spot originally occupied by the phonograph jack to install it. I did have to carefully enlarge the hole slightly with some files. I installed a 1 amp quick-blow fuse and tried the radio several times. It works fine and the fuse does not blow. Now the radio is protected against catastrophic component failure.
Joe
RE: 40-201 now has power - jerryhawthorne - 12-31-2013
Great job Joe. Yesterday I stopped at RS I picked up one of their 4 packs of surface mount fuse holders to mount under the chassis, I guess I like them as I ran out of my first 4 pack! Your getting there!
Regards and happy new year, Jerry
RE: 40-201 now has power - Joeztech - 02-19-2014
I picked up a package of two fuse holders at RS recently. These are the types that mount flat to the chassis underneath or topside to allow a fuse to be clipped into them. I will be using these on some future restoration projects.
I received the variac with isolation transformer from Brenda today and want to say many thanks to her for sending it.
On the 15th this month I attended the Vintage Antique Radio & Phonograph Society meeting in Irving, TX. Bret Frohwein also came and brought the replacement pilot lamp lens for the 40-201. He had mentioned that there are some small slits near the front lens area that allow white light to escape around the barbs that help hold the lens in the cabinet. I used a file and filed down the barbs after first removing the lamp and series resistor that was inside. Then I did a single layer wrap just behind the lens using some Scotch red electrical tape to cover the small slits. This worked and the resulting installed lens does not emit any white light to detract from the overall appearance.
Many thanks go to Bret for his assistance.
Joe