1980 deluxe electric mistress-ways to reduce noise / hum??

[bobster]

hi folks-
i have recently got a deluxe EM from about 1980 in mint condition. works good enough but a bit noisy and hums especially with other pedals eg gain / distortions around it.
are there any simple ways for a techie numbskull like me to help reduce this.?
i would try shielding the transformer or something like that but i dont know what to do or where to start!?
any help appreciated
cheers bob

[bobster]

bumpo!

[sjaltenb]

Hmmm...this circuit is famous for being poorly designed.

In a few days I will have mine hooked up in my multiFX board with an external power supply/transformer. I will let you know what the results are. Basically I removed the 12v regulator and i am simply going to "plug in" my external power to where the onboard regulator output to.

I'll let you know! 

[Cliff Schecht]

hi folks-
i have recently got a deluxe EM from about 1980 in mint condition. works good enough but a bit noisy and hums especially with other pedals eg gain / distortions around it.
are there any simple ways for a techie numbskull like me to help reduce this.?
i would try shielding the transformer or something like that but i dont know what to do or where to start!?
any help appreciated
cheers bob

Start by replacing all of your electrolytic capacitors. These are used for decoupling the power supply voltage (meaning they couple anything other than DC to ground) and work great for this, but they eventually go bad (10 years or so for most cheapo parts). When they go bad, the noise coming in through your power adapter goes right into your circuit and subsequently, your signal. In this case, anything other than pure DC is noise and is bad.

[cpm]

i've got an older EM (not deluxe)
Its also a bit noisy, from the LFO, it make all kinds of "fssh" and "swops".

My first take will be replacing electrolyitcs too, but what about all the aother caps. They are all greenies, would there be any improvement changing them all into the plastic box type?
Also a couple of 4558, maybe some TL072 would be nice too?

[MarcoMike]

Please don't get rid of all that mojo!!! electrolitics are those supposed to die in a couple of decades... but I had some 30years old pedals with internal transformer that were still dead silent!
the greenies should be allright, leave them... and in my opinion the same applies to ICs.

back to the first post, what kind of noise do you hear? if it's AC hum maybe just try to remove the transformer and hook DC to the "power input" (a proper voltage...)

I wouldn't destroy the pedal to make it sound nicer...

[StephenGiles]

I found using batteries was quieter.

[bobster]

hi folks , thanks for replies

the noise im getting is definitely a hum . im not worried about a bit of hiss and swoosh but the grumbling hum sounds bad.
the guts are spotless and signal is strong especially with effect on [ no volume loss to dry sig ] so i feel electro caps will most likely be ok.
its maybe a grounding / design issue but im not savvy enough to work it out.
if anyone could tell me where the regulator is etc and how i could hook batteries up to it instead [ or a wall wart ] then that would be cooooooool.
thanks - bob

[StephenGiles]

Well, that was EH in the 1980s. There should be a 78L15v regulator which looks like a transistor. Didn't someone replace that with a 7815 regulator (watch pin out) which pushes out more current? From memory, the 78L15 runs quite hot. It could be defective after 25 years+.