Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: luthierwnc on March 04, 2024, 08:29:42 pm

Title: need an uncommon small, low-voltage power transformer
Post by: luthierwnc on March 04, 2024, 08:29:42 pm

Hi All,  I'm rebuilding a Premier Reverb 90 tank.  One secondary leg of the power transformer is about half of the other so it's time for another.  In its prime this should have put put about 0-140 volts into a half-wave rectifier.  FWBR is the standard for ones I've read were rehabbed. 

At any rate, I'm not having a lot of luck finding a replacement.  I've included a picture of the little guy.  It measures 1.93" tall by 1.65" long with 2" mounting hole centers.  There's plenty of room for something a little different.  I could live with a center-tapped version.  It drives a modest 12AX7 and a 6AQ5.  The filament is 3.15-0-3.15 VAC but 0-6.3 is fine too 

If anyone has some thoughts on where to get something in that voltage range, I'd love to hear about it.  Thanks, Skip

Title: Re: need an uncommon small, low-voltage power transformer
Post by: sluckey on March 04, 2024, 09:36:40 pm

I would use a Hammond 262D6 (https://www.hammfg.com/files/parts/pdf/262D6.pdf?t=1697661947) available from Hawk Electronics (https://www.hawkusa.com/search?search=262d6&field_current_stock=All&field_rohs_compliant=All&items_per_page=10) for $32.30.

Title: Re: need an uncommon small, low-voltage power transformer
Post by: luthierwnc on March 04, 2024, 09:43:29 pm

Thanks for the idea.  I appreciate it.  sh

Title: Re: need an uncommon small, low-voltage power transformer
Post by: sluckey on March 04, 2024, 09:59:25 pm

Quote from: luthierwnc on March 04, 2024, 08:29:42 pm

One secondary leg of the power transformer is about half of the other so it's time for another.

I don't understand what you mean. There are only two leads on the high voltage secondary. You should be measuring voltage ***BETWEEN*** those two leads. What does your meter say?

Title: Re: need an uncommon small, low-voltage power transformer
Post by: luthierwnc on March 05, 2024, 07:19:25 am

Ooops.  Thanks for catching that.  sh

Title: Re: need an uncommon small, low-voltage power transformer
Post by: sluckey on March 05, 2024, 07:52:56 am

Quote from: luthierwnc on March 05, 2024, 07:19:25 am

Ooops.  Thanks for catching that.  sh

So what voltage do you measure between those two wires?

Title: Re: need an uncommon small, low-voltage power transformer
Post by: PRR on March 05, 2024, 01:08:32 pm

Modified 90.

https://noisemikers.com/wp-content/uploads/2018/08/Premier-90-Reverb-Schematic_updated.jpg