Rewinding A Mains Transformer - Tek 585A - Part 7 - Final.
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- Опубліковано 11 вер 2024
- The mains transformer is re-built, installed in the Tektronix 585A valve oscilloscope & working.
In this episode I re-assemble & run some very high voltage insulation tests. One thing not covered is the noise issue: it was resolved. The tfmr is now quiet and running to spec.
Thanks for sticking with me through this long journey.
Apologies, cock up on the editing front, I'll re-edit & re upload ASAP.
WOW!!!!! I am SO impressed with your rewinding job. It was a real PITA sometimes, but just WOW! That was a huge, very fussy job. Congrats on a tremendous job well done.
Bless you, ta for the kind words. TFW.
Brilliant work Andy! It must be incredibly satisfying to realise the fruit of your labours and have a working scope again. Hats off to you sir!
Thanks you kindly old chap. I never thought I'd get the scope working again, it was a good buzz when I got a trace. TFW.
Great work, incredible patience and tenacity!
Thanks. Not so much patient but stubborn. TFW.
Transformers are varnished to reduce the hum from the core. Small transformers are typically dipped in varnish while large ones are vacuum impregnated with epoxy. Beware that the varnish and epoxy are not types available at your local hardware store.
The last few laminations are typically tapped in with a hammer...GENTLY! to make sure the stack is tight and full. There are no extra pieces of lamination in a recovered core.
Nice job.
Tek 585A is worth the effort, I have a Keithley 182 and a HP 3326A with fried transformers, too.
Currently in the process of converting the HP to dual ring transformer, much simpler than rewinding the original undersized transformer.
Thanks. Having hand wound several toroid tfmr's they are easier to wind than EI tfmr's, just take a bit longer. Good luck with getting your HP3326A going again. TFW.
Well done Andy 👏👏👏 : )
Thanks me duck : ) & TFW.
I recommend hand stacking the core with the E's first and then the I's. Be careful that one leg of an E does not get under the leg of another E. Use a lubricant like WD40 liberally to make the laminations slide together much easier and not get scratched.
Again, thanks for your input.
Good job.
Next up is output transformers then.
Someone came to my house years ago with a Vox AC30 guitar amp and there was nothing inside of it,-NOTHING! -So, I wound the mains and the O/P iron, bought the worst quality caps and resistors I could find, four EL84 valves and it sounded just like Paul McCartney and John Lennon,-success.
I'm also considering trying my hand at some output transformers these days.
The most important thing it seems, is NOT falling for the temptation of overdoing things.
Too much primary inductance and the stray capacitance will kill off the high end of the spectrum etc.
You said you preferred pencil, paper and a calculator instead of software, but the OPT_da-software can estimate bandwith along with all the other parameters. -In this way the software gives you a hint if you try to go overboard with things.
I'll be looking forward to watching your OP transformer winding attempts.
That's very impressive, building an AC30 from scratch. There's not many folk who have the time & patience to learn and to wind tfmr's & rebuild amplifiers etc.
Thanks for the advise about winding OPT's, you make an important point about not overdoing things & I'll give the software another go. TFW.
Commercially wound coils are wound with greater than hand tension on the wire to make the coils fit better. Even then rectangular shaped coils are hammered down in the core area because they tend to round off like footballs.......I worked 15yrs for a transformer mfgr.
Thanks, that's interesting info.