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I have a Hickok 534A tube tester with a busted bias pot that I picked up a few years back. I finally found a replacement so I think it's time to get this puppy going. Information on this exact model seems scarce. There are links to the schematics I’m referencing here and also here. I can’t get a direct link to the individual schematics. There is only a schematic for a 534, no 534A. Hopefully it's close enough. As a side note, the 532 appears to be the same but without the VOM.
I've seen it mentioned that Hickok began using a fuse lamp in series with the wiper of the bias pot ( R7 ) because they were prone to blowing out and that it's a good idea to add this. You can see one in the 533 manual, last page.
Is it really as simple as adding a #49 lamp in series with the wiper? The 533 also has two 500 ohm resistors added (R29 & 30). Are these necessary as well? Does adding these affect the way the bias control works? I think both models use the same 3k pot.
I've seen it mentioned that Hickok began using a fuse lamp in series with the wiper of the bias pot ( R7 ) because they were prone to blowing out and that it's a good idea to add this. You can see one in the 533 manual, last page.
Is it really as simple as adding a #49 lamp in series with the wiper? The 533 also has two 500 ohm resistors added (R29 & 30). Are these necessary as well? Does adding these affect the way the bias control works? I think both models use the same 3k pot.
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