cad equitek e-100 battery supply

Hi everyone,

i made a cheap buy, but unfortunately the mic has some problems on battery power. anyone who knows this model is familiar with the use of 2 9V batteries..... i think that the diode on the small battery pcb has blown.

anyone here who owns this mic and could tell me what type of diode is used?
cause on the circuit diagram in the manual, the diode is not shown.

tia and regards
christoph

i'm not shure if it's the battery supply, but the microphone has a high noise level and crackles and pops when engaged...

regards
cri

It been a few years from when I fixed two of them. IIRC it is based on the Schoeps circuit but uses a Electric(sp) capsule. I would guess the batterys are bad they were two 9 volt NiCad that are trickle charged when the microphone was on phantom.


First try two new batterys

Next if it is still making noise that it apart and check it

Check the diode with a meter in diode mode.

The distance from the back of the capsule to the back metal grill is small and sometimes the metal gets bent enought to touch the center wire

Check for bad connections

Get back to us if this does not help.

thanks gus...

the first thing i did when i got the mic was replacing the batteries - there i found out that the former owner used standard, non rechargable alkalines and tried to charge them with phantom power - the alkalines were even open at the back!
-but new batteries didn't change anything ( i tried rechargable and new alkalines)
-the diode is definitley not conducting (the meter shows 763 in diode mode and approximately 20MOhm in resistance mode (but it's a cheap one, so i'm not shure if i can trust it..))
-the grill is not bent and does not touch anything

0.763V would be a proper forward voltage for a diode. Check your meter with a known-good diode of some sort.

Isn't there a switch in that mic to disable the battery supply? I had a problem with my e100 not passing audio and flipping that switch fixed that.

Kirk

jep there is a switch - but the mic is functioning properly, only with cracks and popples coming through. i already tried to jumper the phantom supply (which is internally possible) to run it from batteries alone, but without luck.

i'm really at my wit's end, the connecter everything seems to be alright....

regards
cri

You might have a problem with the capsule connection - if dirty and/or if the moisture coating is compromised it could have weird pops. Does it get worse with humidity?

hi morbo,

nope - the mic was always stored safely in the original case, and i checked the few connections with a meter - they should be fine....

any other suggestions?
christoph

Replace all the electrolytic caps? Drastic, but that's the next usual source of problems in audio circuits.

http://www.americanmusical.com/manuals/cad/e100_manual.pdf

this is the manual where you can find the shematic of the microphone - wich caps should i try to replace?

thanks
christoph

Is the microphone in the PDF the model you own? The older ones I worked on were transistor no ICs.

Jep - this is my model, and it should be the "older" one - cause the newer "equitek²" series has the "auto-power-off" jumper between the two batteries...

regards
cri

Are the batterys charging? Most 9V nicad are amde of 6 cells with about 1.2V unloaded voltage so If you check the battery out of the microphone it should be >7.2 volts

What do you have for voltages at V18 and V0 using V9 as the ref point. Do this the batterys charged

Do you have a 9V nicad charger if so charge the batterys outside and then install them and see what happens.

Check the connections again it sound like a bad one at the capsule if the battery section is working.

I think that even the original E100s used op-amps - mine does, anyway. The opamp was even part of the product description and marketing.

Regarding capacitors, offhand I don't know exactly which ones. I'd replace all the ones that are aluminum electrolytic, and I'd double-check all connections and solder traces. Did you check for bad solder joints?

hey,

i hope i have found the problem this time - i started to check all the connections again, and there! while i was removing the pcb one lead from the capsule broke off.... now everything seems fine - i will do some test recordings the next days to be shure.....

thanks people!
christoph