![]() Also modernĬaps have better sealing barriers and generally better quality and uniformity of theĬap. OneĬan argue that replacing all is a good idea, especially as you can often catch severalīad ones and not have to re-discover one by one their working state. Often damaging PCB so replacement prudent. Then if it stops working, there's only one component you could have messed up with - if you change 20 capacitors, and then it doesn't work, you've little clue where the issue might be.Įlectrolytics back in the day were pretty much all wet types, and the dielectric fluid Once you've got something old (like this) repaired, then (if you wish) you could change the capacitors - but do it one at a time - testing if it still works between each change. Fault finding isn't randomly testing components either, trace or inject signals, find the suspect area, then measure voltages - then you should be able to isolate which component might be at fault - THEN you can test it.īlindly changing capacitors, and randomly remove components for testing, is very like to cause more problems than you started with - and finding multiple added faults is far harder than finding one original one. I'm also not a big fan of blindly changing electrolytics - fault find first, and see what's wrong - if you should find a faulty electrolytic, change it then. I used it for many years, far faster and easier than digging a signal generator out This allows you to inject at audio, IF, or even RF, due to the harmonics of the squarewave. Personally, one of the first 'jobs' I was given when I started as an apprentice, was to build a signal injector - just a simple multivibrator, running at about 1KHz, and powered from a 1.5V AA battery. ![]() Either inject a signal at the top of the volume control, or monitor th signal there with an external audio amplifier, or a scope if you have one - even acrystal ear piece would work. You're also unlikely to be able to easily find replacements, Germanium transistors are like hens teeth!.įor repairing almost anything, you should almost always use the 'half-split' method, and for a radio the absolute obvious start point is the volume control. since the valve days, it's usually easier not to get confused over positive and negative - just check which battery terminal goes to chassis, and connect the relevent colour probe to that (so red is common for a positive earth system like this one).Īs is typical of this era of radio, the transistors are Germanium and PNP, NPN were still very rare at this point, and much more expensive - hence the almost universal use of PNP devices. ![]()
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