ampex 350 output transformer

Hi guys ,
hope someone can help with this one.
I modded a ampex 350 tape electronics with some great success..it sounds fantastic but recently I've been through two output transformers
both blowing on the primary..can anyone shed some light on common causes why this would happen so I can start to rule some stuff out..
as you can appreciate I don't want to be blowing another one ...so I need a way of sorting this without having one in ...is that possible?

thanks
lance

You can sign onto the Ampex list and talk to the guys who really know this stuff (www.recordist.com). My understanding is that these transformers are having wire insulation failure problems after all of these years. Perhaps it is time to seek a replacement...

Exactley what do your mods involve. I have a 201 I use and would like to understand upgrade ideas...

thanks for that Kevin I'd forgotten about those guys..


as for mods upgrades mainly ...capacitor replacement...new valves..better rectification on the heaters...
I took a signal out of the pre back into the playback section did a bit of jiggery pokkery with some caps to ground to get rid of feedback loop issues and it works very well

thanks
lance

Lance, I don't know if you read the Narma interview, but he had a chassis that replaced the entire 350 electronics because the stock circuit had some issues, mainly distortion.

Maybe someone can find out what exactly he did to modify the orig Ampex circuit.