Schumacher Power Transformer Screws- Replace All?

[baconbadge]

Howdy folks,
Working on a ‘67 Fender Deluxe Reverb and one of the mounting screws on the power transformer is broken off. The original screws are magnetic, and I’ve got four stainless steel replacements, which are not magnetic. Is it fine to just replace the one, or is it better practice to replace all four to keep everything symmetrical in light of eddy currents and what not?
Insanely yours,
Keith

 

[Nyjblbob]

I doubt you would hear any difference at all. Most, if not all, PT's are held by steel bolts.

 

[gadget73]

do they look different? Thats what would bother me.

 

[egellings]

If appearance is paramount, then replace all bolts if an exact replacement is not available. If not, any similar bolt will work, and the xfmr performance will not be changed in any way. What I have seen is that the bolts have plastic or cardboard sleeves on them to prevent any possibility of problems. Good way to check is to measure primary current with all secondaries floating, both with sleeved and un-sleeved bolts. If un-sleeved bolts cause more current than sleeved ones do, then you know what to do-sleeve them.

 

[Tom Bavis]

If two bolts have continuity at both end bells, they form a shorted turn that intercepts a small amount of flux in the core - the flux will induce AC current. Bolts may heat up; the transformer will draw more current. Insulate at one or both ends with shoulder washers. If you can't save the sleeve from the old bolt, use shrink sleeving (no voltage to speak of).

 

[baconbadge]

Yup, they've got these cardboard sleeves to insulate them from the laminations (rolling shutter artifacts with my bench light). Only screws I can get locally are Phillips, which stick out like the proverbial sore thumb against the originals, which is buggin me. I guess I'll replace them all so it doesn't look strange. I just get nervous messing around with it too much. Feels like that first twist that loosens the bolt is like opening the Pharaoh's tomb or something.

 

[crispycircuit]

Heat shrink tubbing will work great as a sub.