Archive for the ‘Repair, alignment’ Category:

2019-11-26 My Radio As A Kid

from FB Comment Nov 26 I inherited old tube radios, I never had a boy’s radio, still don’t today. But I got a 2 transistor SupereX kit that I built. It was a crystal set with an earphone amplifier. Didn’t work very good because I lived a few miles from an AM transmitter and until

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2019-11-25 Fluke Meters, My Experiences

From conversation with Bill Sherman 2019 Nov 25 I had my new Fluke 75 for a year or so and one day I turned it to the off position but the display didn’t go off. I tried it a few times but the only way I could get it to go off was to remove

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2019-11-16 Fixing a Driver Transformer With An Open Primary

Also FB group Building Transistor Radios 2019-11-16 I was working on a Realtone 10 transistor AM radio that had a driver transformer with an open primary. I slit open the wrap and found the tiny fine wire on the right was loose so I soldered it to the heavy wire. But it was still open.

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2019-10-21 Testing Transistor In Circuit

From FB group Vintage Transistor Radios James Ault Adam Bernhardt Maurice Wright is right. The tester puts DC through the device and measures its current gain. But when it’s in circuit it is amplifying AC such as audio or RF, and that’s not what a typical tester does. Any experienced tech will tell you that

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2019-10-07 Zenith Royal 500H Troubleshooting

I got this from eBay, it doesn’t make any sound at all. It has a small crack in one corner but the case is otherwise okay. The screw on the bottom is corroded but the battery holder is in halfway decent shape. It needs a bit of cleaning, the metal is a bit tarnished but

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2019-09-09 Zenith Royal 475 Information

more text below Zenith Royal 475 ARF project & service info links: The Zenith factory schematic and PCB layout is located on page 185 of the Beitmans service literature which is freely available on-line: ** also posted to FB group vintage transistor radios Usually the capacitors are the problem. There are

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2019-06-11 Selenium Rectifier Burned Up, How To Replace

from FB group Vintage Transistor Radios Jun 12 Bob Kirsch has the right idea, but the single replacement diode *must* be rated for 400 V peak inverse voltage or more. A 1N4007 is cheap and readily available. I assume you’re in a country where the AC line voltage is 120 VAC, because the rectified DC

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2019-04-06 HP Transmission Test Set

from FB group Bell Telephone of… Apr 6 (I bought a transmission test set, TTS-4, photo at bottom.) Glenn Peters We had a HP 493something transmission test set for testing up to 56 kb/s lines. I remember seeing the symbols on the green screen, like a carriage return would look like a little ‘CR’. The

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2019-03-19 Radio Alignment Questions

From FB group Building Transistor Radios Mar 20 Bob Kirsch Any recommendation for doing a complete alignment? Documents? I used a HP sweep gen decades ago but I don’t have one now, just an old signal gen. I thought about building a sweep gen but I need to get a few parts. I have bought

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2019-01-27 Replacing Corroded Battery Contacts

From FB group Building Transistor Radios 2018-01-27 Many of the radios I’ve acquired were so corroded that I had to replace metal parts. I used tin can lids to make replacement battery holder contacts. The steel is springy enough to hold cells in place. Scissors can cut the steel, and it can be drilled and

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