Lowfreq
Well-known member
Hey all,
I've had a pair of mc930s that I've used for the best part of a decade now, and one of them has started to lose volume compared to the other. I've attached a pic from tests of sending pink noise to the mics to show the difference.
They've been well looked after, with no real knocks that I can recall, and stored in a nice dry environment.
Tonewise, both mics still sound the same, so I don't know if I'm safe in assuming the capsule is still good.
I checked that I was getting signal on both pin 2 & 3 of the mic going into my preamps, thinking that I could've had a bad sold joint losing half of the balanced signal, but I'm still getting signal on both pin 2 & 3, but still considerably less than the good mic.
I even swapped the pcb into the other mic, and the problem followed the pcb.
I gave the connector to the capsule, and the hi impedance are a good clean with isopropyl, and that suddenly made the mic work again perfectly, but for only 10 minutes.
It then made a popping, rumbling sound and then I was back to where I started with low output on the mic again.
Maybe I could send it to be fixed somewhere, but here in New Zealand our options are limited (and expensive).
I have the service manual which has the schematic, but it looks like a lot of the parts they used are now obsolete.
I've built a few tube mics, but I haven't really dived into sdc or fets at all yet (let alone smd components), since what I already had worked until recently.
Has anyone dealt with one of these before? It's the working for 10 mins and then popping and rumbling back into a broken mic that's baffling me.
Steve
I've had a pair of mc930s that I've used for the best part of a decade now, and one of them has started to lose volume compared to the other. I've attached a pic from tests of sending pink noise to the mics to show the difference.
They've been well looked after, with no real knocks that I can recall, and stored in a nice dry environment.
Tonewise, both mics still sound the same, so I don't know if I'm safe in assuming the capsule is still good.
I checked that I was getting signal on both pin 2 & 3 of the mic going into my preamps, thinking that I could've had a bad sold joint losing half of the balanced signal, but I'm still getting signal on both pin 2 & 3, but still considerably less than the good mic.
I even swapped the pcb into the other mic, and the problem followed the pcb.
I gave the connector to the capsule, and the hi impedance are a good clean with isopropyl, and that suddenly made the mic work again perfectly, but for only 10 minutes.
It then made a popping, rumbling sound and then I was back to where I started with low output on the mic again.
Maybe I could send it to be fixed somewhere, but here in New Zealand our options are limited (and expensive).
I have the service manual which has the schematic, but it looks like a lot of the parts they used are now obsolete.
I've built a few tube mics, but I haven't really dived into sdc or fets at all yet (let alone smd components), since what I already had worked until recently.
Has anyone dealt with one of these before? It's the working for 10 mins and then popping and rumbling back into a broken mic that's baffling me.
Steve