mdye
Active Member
I recently acquired a clean Dynaco SCA-35 amp that has the original Z565 OPTs with cloth leads. I haven't fired it up yet; I've just been taking some initial readings with a multimeter of the resistors, caps and transformers...looking for anything out of spec, etc.
I'm getting some interesting readings when measuring the DC resistance of both OPT's primaries (all readings are in ohms, measured from the B+ tap):
Transformer #1
Blue: 174
Green: 44
Blue/White: 201
Green/White: 51
Transformer #2
Blue: 375
Green: 92
Blue/White: 197
Green/White: 50
Transformer #1 seems to be in line with other people's measurements of the Z565 that I've found online. As you can see, Transformer #2 is reading a little more than twice as much resistance on one half of it's primary.
I know that DC resistance measurements are by no means the ultimate test of a transformer (unless you're getting readings that are badly off), but does it make sense that two identical, healthy transformers would give results like the above? Do I have something to be concerned about, or is this much ado about nothing?
I'm getting some interesting readings when measuring the DC resistance of both OPT's primaries (all readings are in ohms, measured from the B+ tap):
Transformer #1
Blue: 174
Green: 44
Blue/White: 201
Green/White: 51
Transformer #2
Blue: 375
Green: 92
Blue/White: 197
Green/White: 50
Transformer #1 seems to be in line with other people's measurements of the Z565 that I've found online. As you can see, Transformer #2 is reading a little more than twice as much resistance on one half of it's primary.
I know that DC resistance measurements are by no means the ultimate test of a transformer (unless you're getting readings that are badly off), but does it make sense that two identical, healthy transformers would give results like the above? Do I have something to be concerned about, or is this much ado about nothing?