Archive for Calrec

Calrec PQ 1161 Mic Pre & EQs

Posted in Repaired with tags , , , , , , , , , on September 29, 2013 by AnalogAudioRepair

I have always been interested in Calrec modules.  They are touted as being “as good as Neve”, “built to BBC specs”, and on and on.  Recently I found myself with a few modules on my bench from two different clients.  The first two were racked and powered but the second unit was noisy.  The other module came from a larger rack with 1181 and 1161 modules.  It had a different problem which I will get to later.  Besides the beautiful construction of these units, the first big thing I noticed was that the pair had all discrete amplifier cards, while the single unit had ICs (chips) on the cards!  It seems Calrec changed over at some point between the serial numbers in the 450 range and those in the 600 range.

The discrete amplifier cards are easy to pull out and swap for quick troubleshooting.  That was good because it allowed me to pinpoint the output amplifier as the noisy board.  Then probing with the oscilloscope tracked the noise down to the first transistor on the card.  Replaced the part, and it spec’ed just like the good channel again.

Thankfully the module with ICs had a much simpler problem, though one to watch out for!  These modules were sold with no light bulbs in the EQ and phase reverse switches.  The owner bought bulbs, put one in the EQ switch and watched smoke come pouring out!  Fearing the worst, he brought me the module.  Thankfully, there is a current limiting resistor which gave it’s life (and gave up the magic smoke) to save the day.  The problem was the way that the bulb socket mounts on the switch.  It is a plastic holder that straddles the switch and is soldered to the first pin on either side.  However, on this one module the other pins were not bent down for some reason (as they were on all the other modules) so pushing in the bulb caused it to short against the second pin!  Replacing the 100 ohm resistor and bending the pins was all it took to get things back to normal.

Image

Calrec PQ 1161 Preamp & EQ

Calrec PQ 1161 Preamp & EQ

Calrec chip amplifier cards B202/205/210

Calrec chip amplifier cards B202/205/210

Calrec chip amplifier cards B202/205/210

Calrec chip amplifier cards B202/205/210

Calrec discrete amplifier cards B202/205/210

Calrec discrete amplifier cards B202/205/210

Calrec discrete amplifier cards B202/205/210

Calrec discrete amplifier cards B202/205/210

Calrec discrete amplifier card B202/205/210 PCB Front

Calrec discrete amplifier card B202/205/210 PCB Front

Calrec discrete amplifier card B202/205/210 PCB Back

Calrec discrete amplifier card B202/205/210 PCB Back

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