Input2
New Member
Heathkit AA-151 Heathkit has always been my favorite maybe it is because I built my first Heathkit way back in 1966, so I have a real soft spot for Heathkit.
Just finished rebuilding this amp with all new resistors and capacitors,everything is pretty well straight forward except wiring in the new E-caps which are 30-30uf at 350 volts and 60-25uf at 500-450 volts.
When wiring in the new individual E-caps the only place to mount then is underneath the chassis and with the longer path to ground from the Negative of side of the E-cap , hum can be a problem again. Refusing to believe that, only with the help of a friend and a trusty Heathkit IT-12, I could pick up the hum noise from the 18 gauge wire that was first used, changing all the wire to number 14 gauge solved the problem.
Remember that when recapping this type of high gain amp, or you will pull your hair out, like I did.
I find that when rebuilding vintage equipment, replace all the capacitors and resistors, don't waste time testing old resistors as most would be out of spec by 30 percent and even more when the unit is working.
Defiantly replace the Electrolytic caps to make it safe to use , don't try to form them up, I never had any luck with that in amplifiers and why chance burning out the power transformer.
As far as the amp goes in performance, it sounds beautiful and smooth with zero hum, but is a bit light on power as to what I am use to.
Hope you all like vintage equipment like the AA-151, there are many posts on different forums about the AA-151 and it's performance.
The last picture should have been first, it shows how I am cleaning most vintage equipment to remove years of grim, tar from smoking enviroment. Just be careful not to get water in the transformers and pots.
