October 6, 2019 at 12:34 pm #15418urbanopolisParticipant
I am looking at the older Alice 62/3 mixer and I am curious about it’s inputs. It only has 1/4″ inputs? There is a hi/low toggle as well. Are there mic preamps in this or is this a transformer-less line mixer only?
It is unlike any of the other 62/3 mixer I have seen visually as well.
any help would be appreciated.
Attachments:You must be logged in to view attached files.October 7, 2019 at 8:41 am #16195Ted FletcherKeymaster
The very early ones, of which there were only a handful, were transformerless and I don’t have the circuit for that one.
The slightly later ones had a mic transformer and the switch just switched the transformer in and out.
Here’s the only circuit I have…..
Attachments:You must be logged in to view attached files.October 18, 2019 at 11:30 pm #16196grbgbrnrParticipant
I am the lucky auction winner for the above mentioned 62/3. I’m excited to restore it to it’s former glory but it looks like it’s going to take some work. The unit powers on and each channel passes signal. Both the left and right channels of the limiter work too. However, the signal cuts drastically if all the pan knobs are not at center and the majority of the pots cut in and out with movement.
I’ve read your other threads that mention cleaning the pots with wd-40 which I’ll try once I get it opened up. I assume all capacitors will need updating. You mentioned also somewhere about updating the power supply to a 24v single rail switching supply. Would you recommend one specifically? Is the board looking for 24v DC output? Any help is much appreciated. I can post more photos of the guts once I get started.
TysonOctober 19, 2019 at 8:37 am #16197Ted FletcherKeymaster
I can’t be absolutely sure, but I would expect that this one has mic transformers which switch into circuit with the ‘Hi/Lo’ switch.
Note that it is fitted with PPMs so it must have been originally intended for a broadcast application.
That model (the 62/3) was the mixer model immediately before the introduction of the 828 Mk1 and the circuitry is very similar; the mic amp circuit (shown on this ‘subject’ in an earlier post) uses the same transformer as all the later 828s.
I would NOT recommend replacing capacitors unless they are faulty; as I have said often, capacitors have extremely long lives unless they are subjected to high temperatures. Old valve equipment often needed ‘recapping’, but I rarely come across faulty electrolytics in equipment that runs at normal room temperatures.
As for power supplies, I don’t want to get into recommendations. When I am repairing/updating equipment I often use Chinese manufactured switch-mode supplies but it’s not that simple; these supplies are reliable and efficient, but they often produce awful interference radiation that is not simple to deal with. If you are not experienced in dealing with power supplies generally, then be wary.
I believe the 62/3 mixer needs just a single 22 or 24V DC supply.October 20, 2019 at 4:50 pm #16198grbgbrnrParticipant
Thank you for the reply. I got to spend more time with the board yesterday. I worked most of the knobs and faders back and forth and found they worked a bit better. One of the middle eq knobs is non responsive so I’m hoping it’s just a loose connection and one of the gain stage knobs goes either 0% or 100% so I’m wondering if there’s a short somewhere. Otherwise it’s sounding incredible. It sure sounds like there’s some transformer magic happening when the low impedance switch is engaged.
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