What's this symptomatic of?

[Franz]

Let's say you have a combo sporting integrated circuits, and the every C on it plays at a low volume (but isn't dead), what is that symptomatic of? Something small like a loose wire, or something major like a dead oscillator?

Now let's say JUST ONE note is quiet...is that the same problem, or just a dirty contact?

Thanks!

[karl]

Hello Franz,

To start out, clean all the key contacts first.
What kind of combo are we talking about? There are many different ways to answer this question.

Of the Ones with IC's in it:
The early ones use a set of master oscillators for all the high notes with divide down integrated circuits, to generate each octave. If all the C notes play, but are a lower volume than the rest. ( but are still a C note ) The oscillator works but something is pulling down the signal to each note. possibly a bypass capacitor in the signal chain. A low volume note would indicate a problem with one of the divide down circuits. This could be an old capacitor, a bad solder joint, loose wire or a dirty contact.

Newer units may have a large integrated circuit which handles all of the above mentioned functions. This Integrated circuit could be failed and that would be a hard chip to find. On the other hand this could be bad solder joints, loose wires, dirty contacts, etc.

Best Regards
Karl

[mtwallet]

let us know what kinda organ is this

if all the C's are low, I would check the transistor of the 1st division

if only one C is quiet, I'd check the key itself and its wires, and then the division concerned by this note

[Franz]

Wurlitzer 7300 ....I'm a real idiot with electronics. So let me know if something I could feasibly fix myself, i.e. clean something or reattach something obvious.

Thanks a ton guys!

[fleshtonejm]

I've had that issue with my continental: all C's (coincidently) were getting very quiet after a couple of hours of rehearsal, until they went quiet all the time.
A transistor had blown, don't ask me where on the tone generator, I wouldn't know. I've had it fixed by this old guy who used to be a techy back in the 70's;

[Franz]

I'm getting the impression this could be serious, especially without the part.

And now I've got issues with my Mini Compact. Dratts!

Anyways, thanks everyone for your help.

[Rod MPS]

I think that we will always have issues like these with 30-40 year old instruments. Things go bad over time even when thy are well cared for. Many of these instruments were exposed to the most destructive force in nature back in the 60's... teenagers! Bounced and banged in and out of car trunks and vans, soaked in beer and coated with tobacco smoke, eventually left to rot in a dank basement or garage for decades.

It is a wonder that any of these things still work!

[fleshtonejm]

soaked in beer and coated with tobacco smoke,

Well, I must say this is description fits me pretty well, except for the smoke part since I dont smoke.

oh, I'm not a teenager any longer, well on my ID that is... ;D

[arch]

Rod, I agree. Just reading some of Karl's post have help me trouble shoot that Kustom. It not only was beat up (in road cases), beer spillt on it. ( brown thick stuff under the keys). I played a place in in a basement setting where the cold water feed was right above where me and the bass amp were. The more people, the more condensation on the pipe. It would get so bad that i would get shocked through the water on the keys.
I read all the post at work , but the filter will not let me log in. And I seldom have time to get on line at home.
Love the site.
Arch