Yet another transformer question outta me... I bought an X100B locally last week, serial number around 14000. One of the output transformers was shorted - unit was inexpensive based on this known issue. I have a 400, serial number about 59000, that is rusty crusty and incomplete to scavenge some output transformers from. Both these units are PP 7868 based, so it should work right? That's what I thought, so I installed one last night and voila! it works. I mentioned this in Tim's KX100 thread and Larry mentioned the impedance of the X transformers is higher than the early ones. I started reading Dave's long post on the topic of X vs non-X 400 transformers and now I'm confused. What if any circuit modifications do I need to do in order to use these AX type 400 transformers in the X100B. I can see the voltages are bit higher in the 400, but should this matter? It reads like I ought to install Dave's EFB(tm) in the X100B to use the AX 400 transformers, or find another to use. I have a pair of 500B units I can use. Below in order (in the style of Dave): 1. X100B 10001 - 19999 output section. 2. 400 48001 and on output section 3 - 6. the unit in question. Looks pretty good, but when I got it one of the two piece knobs was destroyed, all brights were off something else entirely that fit poorly, had some sort of toy jewel glued over the light hole -the glue residue from which was all over the face plate and a ton of work to remove, three of the switches were from some other unit - I replaced these the night before last. Just started cleaning up the chassis as can be seen. Lots of caps have been replaced, so it should give years of service once it's together and set up.