On to the Mark III

Pretty much finished the ST70 except for a few minor issues and moving on to an ancient Mark III that has been sitting for a long, long time. I see that where the old wafer-like rectifier was located on the ST, in the Mark III there seems to be a black cube looking component approx. 3/4" x 1/2" and about 1" tall....I apologize can not post photo right now I have to get another photo server...but one side is connected to the black/red cloth lead to the tranny, other side to a 50mfd 150 electrolytic cap and a resistor going to a terminal strip. Is this yet another style of rectifier, which is replaced by the modern diode as noted in the ST fix? If so I will get one and take this thing out. Which direction should the diode be oriented, i.e., stripes towards red/black tranny side or other way around? You guys have been a valuable resource thanks. IA

Hey trying this photo link....Mark III
http://www.flickr.com/photos/77404494@N03/6947744090/

Hi --

The Red-Black wire from the power transformer goes to the Banded-End of a 1N4007 or UF4007 type diode. You can use 1N4005-6-7 types, I use the 4007 because I have them.

The other parts (Resistor and Capacitor) go to the other end of the diode.

There is a newer version of the Dynaco Mark III Assembly Manual somewhere on the web (I don't remember where I got mine from) that shows the stock dynaco parts connected to a 1N400x type diode instead of the traditional Selenium Rectifier --- try googling "Dynaco Mark III Assembly PDF" without the quotes.

Have fun,
Stew

Hi Bob ---

The version of the manual at tubes4hifi site is not what I was referring to.

Somewher in my "Web Travels" I downloaded a version of the manual that had Dynaco's Changes for the KT-88 tube and also showed a pictorial diagram (last page) with the Selenium Rectifier replaced by a 1N400x type diode.

Is there anyway to send you a copy of the newer manual so that it might be posted here? I don't have the capability to post pictures or documents somewhere else.

Please let me know,
Stew