Replacing Tubes

[Guest]

Hello again. I have the original tubes in my L-112. It was missing the 12au7 in the percussion (which i took one from the vibrato unit to fill...have to have the vibrato tabs down for everything to work)</P>


What will I gain from retubing specifically? There is some hum. I need to get deoxit and spray it in the tube sockets I know for one. I don't know if any caps need replacing. I recently oiled everything and the tone is solid. Will new tubes help protect the rest of the electronics as I have read elsewhere?</P>


I need to know if it will be worth the 120 buck to retube the whole thing or if I should just get one more 12au7 and do the deoxit thing?</P>


Thanks so much.</P>

[bremar]

Re: Replacing Tubes



I wouldn't change any tubes unless I knew they were bad. Just buy a 12au7 for now. </p>

The hum could be a bad tube, or it could be filter caps, or it could be something else. It's probably the caps, but you might as well test the tubes first since that's easier. You can take them all out and take them to a guitar amp guy to test. While you're there, see how much he wants to recap your organ amp.</p>

Of course, cleaning your tube sockets and tube pins is always a good start. Spray a tiny bit of DeOxit in the socket, then put the tube in and out a couple times.</p>

I should let someone smarter weigh in on this, but from what I understand, if a tube goes bad, it shouldn't harm anything else in the organ, but if a filter cap completely fails, it may harm the output transformer.</p>

Good luck.</p>

[Guest]

Re: Replacing Tubes



thanks! i have a friend who i just remembered may have a tube tester...as he builds stereo amps (macintosh etc) totally spaced this out. he probably has a tube i could use too. </P>


otherwise i will be buying some deoxit tonight or other elctric spray if i cannot find deoxit</P>

[Guest]

Re: Replacing Tubes

I agree about not replacing the tubes yet. Go ahead and test them but you typically see them last longer than guitar amps because the design doesn't drive them as hard as say the EL84 tubes in a Vox AC30. Heat is the biggest enemy to a tube's lifespan.

[Clarion]

Re: Replacing Tubes



[quote user="drums"] What will I gain from retubing specifically? There is some hum. I need to get deoxit and spray it in the tube sockets I know for one. I don't know if any caps need replacing. I recently oiled everything and the tone is solid. Will new tubes help protect the rest of the electronics as I have read elsewhere.[/quote]</P>


New tubes won't offer you any benefit. Basiscally, either they work or they don't, although they do tend to fade away; and may not work in some applications as they get older. Old tubes do not cause hum! Although it may happen in rare instances where the cathode shorts to the filament.</P>


Hammond had the propensity to create some rather crappy power supplies. And for the sake of thefew extra farthings and thefew extra microfards necessary to create ahum-free power supply; they opted for the elcheapo approach. [:O]Adding one or two 100 mfd capacitors across the high voltage output of the power supply is likely to offer signicant gains in hum reduction!</P>


Been there. Done that!</P>