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I tried replacing the 20 mFd capacitor with a 22 mFd, 160V capacitor purchased from Mouser. The voltage at the selenium rectifier cathode is 90.5 VDC and 1.04 VAC ripple as measured by the Fluke. Since there is 0.9V drop across the 33 ohm resistor, it appears that 27 mA current is flowing. The voltage at the selenium rectifier anode is 119.1 VAC. The transformer high voltage secondary voltage is 120 VAC. ![]() The voltage across the transformer primary is 118.3 VAC, which is house voltage. (See the schematic diagram per the above link.) Should I expect that a VTVM which is powered by house AC will be able to measure house AC voltage accurately, or is there some ground loop issue? I had hoped that the power transformer would isolate the VTVM circuitry from the AC line. However, when I tried measuring AC house voltage, the reading was way off. I used lab power supplies as the DC voltage source, and was able to calibrate DC voltage measurements fairly well. When I received it, I tried calibrating it using my Fluke 87 multimeter as the reference. REPLACING A SELENIUM RECTIFIER WITH A SILICON DIODE MANUAL(Here's a link that provides photos and the owner's manual including schematic diagram.) My dad recently gave me his Simpson 303 VTVM. pt.This question is for electronics old-timers. Can I do it justice? Nordmende Super 250-9 rest. #tuberadios #radiorestoration I got this one as a gift. ![]() Hope this helps you, but remember that high voltages are dangerous! His video is here, and I highly recommend you see it. I decided to try and test it, following the method that TRX Bench presented in a similar video. In my current project, I suspected an EL41 output tube to be faulty, but unfortunately did not have any others on hand. I normally just keep a few (known working) tubes on hand, and swap one in if I suspect a tube has failed. I believe they are too bulky and expensive for my limited needs. Is this EL41 any good? Electronics Old and New by M Caldeira | In my hobby restoring tube radios, I have so far resisted getting a tube tester. REPLACING A SELENIUM RECTIFIER WITH A SILICON DIODE HOW TOHow to test a tube without a Tube Tester. My goal for this stage of the process was to get the audio section restored and tested, and that is what is covered in this video. So, onwards as per my usual modus operandi: First the power supply, then the audio section. I was afraid the problem may have been the output tube, an EL41, which I had no replacement for, but fortunately that was not the case. 2 Electronics Old and New by M Caldeira | As was obvious from the first video, the audio level on this Nordmende Super 250-9 was disappointingly low. See also playlists on some other completed restoration projects. HowTo's: Various videos on some simple techniques and projects: REPLACING A SELENIUM RECTIFIER WITH A SILICON DIODE SERIESRESTORATION BUILDING BLOCKS: A series of videos showing detailed steps used the restoration process of tube equipment: ![]() _HUNDREDS OF OTHER VIDEOS TO CHOOSE FROM_ #tuberadios #antiqueradio #radiorestoration I got lucky, as I was testing this radio with the Dimbuld Tester in use, so it was a good reminder that you should not become complacent.Īnyway, it gets a little more exciting, so I won't complain. With tube radios, the results can be dangerous, or, as was the case here, you could blow things up. When you get quite experienced in this hobby, you can become a little careless. 3 #PCBWay# Electronics Old and New by M Caldeira | Only $5 for 10 PCBs and every new member get $5 bonus. This Dimwit was really saved by the Dimbulb Tester. You can also watch how I re-stuff the electrolytic filter capacitors of this radio here:Įnjoy, and comment if you so desire. ![]() This radio is the object of a series of videos on its restoration, which you can see here: I take you through my way of 're-stuffing' a selenium rectifier on a SABA Freiburg W2 with 4 silicon diodes. ©2022 Home About Privacy Replace Selenium rectifier with silicon diodes Electronics Old and New by M Caldeira | Tube radios from the 50s often have selenium rectifiers in the power supply, which may need to be replaced, preferably with a silicon diode bridge. ![]()
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