Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: LooseChange on July 05, 2010, 04:21:16 pm

Title: Hammond M100 Ao29 on the bench
Post by: LooseChange on July 05, 2010, 04:21:16 pm

I have the chassis on the bench.
http://www.hammondb3organ.net/schematics/hammond/organs/m100/m100.php?command=display&template=1&image=http://www.hammondb3organ.net/schematics/hammond/organs/m100/schem_R.JPG&descpath=/var/www/hammondb3organ.net/schematics/hammond/organs/m100/desc/schem_R.txt&directory=/var/www/hammondb3organ.net/schematics/hammond/organs/m100 (http://www.hammondb3organ.net/schematics/hammond/organs/m100/m100.php?command=display&template=1&image=http://www.hammondb3organ.net/schematics/hammond/organs/m100/schem_R.JPG&descpath=/var/www/hammondb3organ.net/schematics/hammond/organs/m100/desc/schem_R.txt&directory=/var/www/hammondb3organ.net/schematics/hammond/organs/m100)
All new tubes. Did a power supply filter cap change.
The PT gets hot quickly. Too hot to touch. The B+ is a bit low.  All this before and after the cap job.
I measureed the AC curent at 1.8 amps.
What could be wrong?

Title: Re: Hammond M100 Ao29 on the bench
Post by: FYL on July 05, 2010, 05:07:21 pm

Shorted turns in the PT maybe. Does the PT still get hot with an unloaded secondary?

Title: Re: Hammond M100 Ao29 on the bench
Post by: LooseChange on July 06, 2010, 05:01:51 am

Yes... Unloaded still hot.  Got to find a replacement.
It's been a transformer market at the shop lately.

Title: Re: Hammond M100 Ao29 on the bench
Post by: LooseChange on July 06, 2010, 05:17:58 am

Okay... recommndations for the PT??
320-0-320 on the HV
5v-3A filament
6.3v with center tap (what amperage?)

Title: Re: Hammond M100 Ao29 on the bench
Post by: Dave on July 06, 2010, 07:11:29 am

Look on Fleabay. They are there all the time. M-100 series, M-3, and L-100 series will all fit and work fine.
Possible exception.... some early M3's had a physically larger PT but it was grey in color so if you see an M3 PT that is black you'll be good to go.

Dave

Title: Re: Hammond M100 Ao29 on the bench
Post by: FYL on July 06, 2010, 09:12:20 am

Quote

Okay... recommndations for the PT??

According to my docs the AO29 is supposed to use a H-AO-22111-1 power transformer spec'ed at 355-0-355V unloaded and 320-0-320V @ 150mA, 5V @ 3A, 6.3V @ 4A. But I'm no Hammond expert and can't vouch for this info.

Finding a spare is quite easy: there are many cannibalized amps and spares floating around.