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Sony C37p-

Out of service since the last hammering from a drumstick crushed the grill, and tore the capsule membrane.

I forced out the grill a bit to free up some room and replaced the capsule (sony still sells them). Reskinning is about as expensive as the new one.
Sounds great!

Recapped and tested a couple Altec 539a power supplies (for 195 mic).

EApreq prepwork.

Discovered one of our ATR 1/4" 2-track repro heads is cooked. There was goofiness with adjusting the azimuth and the sensitivity was low. Looking at the actual head, I could see at the top and bottom, the gap was widening ("opening up"). Now to hunt for a replacement. Spares are getting harder to come by.

JSP recapped another set of Altec 195 supplies.

-Elesewhere-

Universal Audio LA-3 reissue-

Gain reduction meter showing maximum attenuation, with no signal present. Compression function, working however.

T4b not working. Swapped it with a companion unit, and all was good. UA's customer service was nonexistent on the phone or online. They had a chat bot who wouldn't stop asking me what OS I was trying to run my real world LA-3. Brian Fox had a spare I bought off him. Thanks.


ITI MEP 230 stereo EQ-

Broken power switch, and low frequency shelf select switch.
No other notes about whether or not it worked. The insides look pretty rough. There are 10 epoxy-encased mystery amps or amps and filters, and the power supply caps are original. These things are notoriously buggy.

Replaced the two switches and powered it up. On the bench, everything seems to be functioning, except the mid band on the left channel did nothing. No listening tests yet.

Studer A820MCH Mkii-

JSP recapped all NRS Control boards (240 bipolar caps).


EAPreq (2-chan rack version) construction.

Finished two EApreqs.

AKG 451E -

No low end.

JSP recapped all the Repro, Record and HF Driver Boards on the Studer A820MCH MKII

Studer A820MCH mkII-

Channel 22 pops when switching between Sync and Repro monitoring.

Swapped Channel 22's Repro/Sync Amplifier and NRS Control boards with two separate channels to narrow it down to the Repro/Sync Amp. Traced the problem to a faulty SD214 MOSFET switch on the Repro/Sync Amplifier board. The the switching control voltage should measure from -15 to +15 volts at the gate. This one was locked at roughy 8 volts in either mode. I'd tell you the location on the schematic, but we don't have the repro half of the Repro/Sync Amplifier 1.820.810 schematic. This was the latest version of the board built to allow sync and repro playback simultaneously. If anyone's got it, please share. I have the complete machine document scans Studer provided before they closed, this isn't in there. If you were looking at the older repro amp board schematic 1.820.710 the part would be IC 6.

Channel 9's Repro and Sync output is dead for the first 10 minutes or so, after power up, then works fine thereafter

Problem follows the Repro Sync Amplifier (1.820.810) had had some sloppy repair work with burned pads and traces. A jumper was not fully soldered to a ruptured trace it was meant to mend. I pulled it, and ran a more direct jumper, bypassing the trace entirely. The location of this was just after the Sync/Repro signal switch buffer amplifier. Betwen IC101 and C109 on this odd board. IC14 and C35 on a regular 1.820.710 board.

Ampex ATR #1 (transfer suite).

Replaced 1/4" 2 track repro head with a Flux Magnetics guy.
Adjusted tape lifters.

Ampex ATR #1 -

Timer roller surface (aluminum) has a sharp divot, appears to have been dinged with something.

Replaced with an Athan roller. So clean and new!


Josephson C700 S/N 001 -

Buzzing, low, swooshing sound on omni capsule output.

One of the output legs broke free of the amplifier pcb. WTF? Re-soldered, now is normal (great).


Lomo 19a13-

No output.

Busted wire on the mic end cable connector.

While testing, the stereo PSU measured a pretty low Filament voltage (4.15vdc). I like to target 5.5v with these mics. The design is an aftermarket deal using two separate LM317s (one for each mic) configured in such a way that ramped up the voltage slowly as the filament warms up. It's fixed, so I'll play around with the resistors to get what I want later.

Done

Ampex ATR #4 -

Right meter not working, showing randomly lower levels.

Exercised VU/PPM switch, connectors, no joy.
Exercised R21 (meter level calibration), joy.


Ampex ATR #1-

Cork pad protecting the supply side tension arm inner limit fell off. Glued it back.


Flying Faders-

Channel 24's fader doesn't sense touch, and thinks it's always at the bottom of it's travel (can't be linked or grouped).

Tested on the bench and the logic state of the touch wouldn't switch. Swapped a couple of chips related to it with no success. Discovered no continuity between the knob and associated pin on the connector from the fader. Opened the fader up and discovered the wiper wire for the "touch" track that was origially soldered to the frame of the knob broke loose. Resoldered. All is right again.