Lomo 19a9-

Dead. Power supply working...

Busted wire in the mic end of the mic cable. Reattached, and better strain-relieved.

Greg wrote: Wed May 29, 2024 12:40 pm Ampex ATR #4 -

Tape played off the end of the reel, and the tension rollers froze in the innermost position, causing the reel motors to spin full speed, and then the capstan motor took off at full speed. After powering down, Taylor discovered some blown up parts on the capstan servo board. Tried a spare, and things didn't work quite right still.

Not sure what the sequence of events is, but on the Capstan Servo card, the +12 volt regulator fried passing the "20 volt" rail on through to the +12 volt path. The TO-220 transistor blew apart! As did a 2n3904 and 2n3906. A22, a MC1458 dual op amp had a bulge and crack in it.
Replaced the following busted parts; Q, 8, Q16, Q17, A22, and VR1. The board will power up on the bench with no other obvious issues. I'll test in the machine later.

For now, I calibrated the tachometer gains in the spare board, and the capstan runs smoothly. This can be tested discretely, without the need to load tape by simply removing the Reel Servo board.

Discovered little shiny orange bits in the card cage, and found two tantalum capacitors on the Reel Servo board had detonated. These were bypass capacitors C40, C41, for the ±12 volt rails coming from the destroyed Capstan Servo board, suggesting the -12 volt rail was high for a moment. Replaced those. That board, with the spare capstan servo board is working well in the machine today.

Can I just post this on Gearspace for all of the threads titled "Thinking about switching to recording on tape"?

Neotek Elite -

Work on reswitched stereo input channel.

Work on EApreq500, the upcoming API500-format version of our preamp.


Hiwatt Custom 100

Dead

Blown fuse. That was easy.
Messed around loudly with it for a while to make sure.


Traynor YBA-1B "smoked" in session.

We'll see. Brian?

Both were being used with our Hiwatt 4x12 cabinet, which made me suspect a shorting input jack or some goofy speaker meltdown, but other than the jack being ever so slightly loose, nothing noticed. Sound was even out of each speaker. The Hiwatt amp impedance was set to 4Ω and the cabinet is 16Ω.

Greg wrote: Wed May 29, 2024 12:40 pm Ampex ATR #4 -

Tape played off the end of the reel, and the tension rollers froze in the innermost position, causing the reel motors to spin full speed, and then the capstan motor took off at full speed. After powering down, Taylor discovered some blown up parts on the capstan servo board. Tried a spare, and things didn't work quite right still.

Not sure what the sequence of events is, but on the Capstan Servo card, the +12 volt regulator fried passing the "20 volt" rail on through to the +12 volt path. The TO-220 transistor blew apart! As did a 2n3904 and 2n3906. A22, a MC1458 dual op amp had a bulge and crack in it.
Replaced the following busted parts; Q, 8, Q16, Q17, A22, and VR1. The board will power up on the bench with no other obvious issues. I'll test in the machine later.

For now, I calibrated the tachometer gains in the spare board, and the capstan runs smoothly. This can be tested discretely, without the need to load tape by simply removing the Reel Servo board.

Discovered little shiny orange bits in the card cage, and found two tantalum capacitors on the Reel Servo board had detonated. These were bypass capacitors C40, C41, for the ±12 volt rails coming from the destroyed Capstan Servo board, suggesting the -12 volt rail was high for a moment. Replaced those. That board, with the spare capstan servo board is working well in the machine today.

This is why tape is more fun than digital

Studer A820MCH #1245-

Deck-top controls froze, meter bridge, and LCD screens went dark.

Replaced MP Unit Master board with spare.
Later, erased RAM, checked battery, and upgraded to .25 with the reset modification (see 20.050.754.12). I don't think the reset mod fixed this, but it's supposed to be done on all the battery powered boards.
Reentered all the data lost in the process. Testing all day.

Studer A820MCH #1415-

Meter bridge goes dark, displays on the LCD "no communication panel audio".
Resetting would temporarily resolve the issue.

Tried swapping -
Master to Audio IF 820.756
Communication Controller 820.718

Later bug- Channels 15-17 switched from sync to repro on their own.

Exercised meter connection.

Sent some RCA mics off to Cole Picks

-Elsewhere-

Neotek SII (not ours)

I installed an trouble-shot a 28 channel Series II in a fancy spot in the Catskills. One channel had a problem with it's high frequency band EQ. The frequency select was way south of what it was supposed to be (10kHz was 2k...). Found some janky repairs including a resistor in the filter that was replaced with the wrong one.
Rewet a bunch of broken solder joints on the channel headers.

Neotek Elite (not ours).
Cleaned a number of mute buttons. You do this by carefully popping off the cap and taking the metal dome out, scrub the two contacts inside and the underside of the metal dome, carefully reinstall everything. I found a lightly magnetized flathead screwdriver is super handy for this.

Studer A820MCH (not ours)
Channel 19 occasionally loses its input.
Swapping cards, I found the problem followed the line amplifier. I found a barely touching solder joint for the "input" trim pot jumper (later models have input and output level trims on a faceplate). Cleaned, re-stripped and soldered the wire. All's good.

Ampex ATR (not ours)
Installed new fan
Removed, cleaned, lubricated, reinstalled and adjusted tape lifter arms. Tape lifter sleeves rotated to fresh surface.

Studer J37s 1" 4-tracks (two of them)
Replaced horribly Corroded XLRs with new Neutrik ones.
Preliminary check out of transport functions. I'll be seeing these again. Not looking forward to the calibration, as there's limited access to the amplifiers. This is apparently before they adopted the culture of making things easy to access, and a breeze to align.

-Still Elsewhere-

Studer B67 mono 1/4"-
Installed and aligned recently relapped heads.

Erase function not working, only erasing about 20dB worth of signal.

-Found the oscillator board's output measured around 20vac as opposed to the expected 50+ volts at the test points. Fault sourced to a shorted tantalum capacitor in the oscillator board (C5). Replaced that and the rest of the tantalums (C3, was the only original electrolytic, earlier replaced). Reinstalled and tested, readjusting the Bias and Erase jumpers to suitable ranges of operation. Machine fully calibrated.

Studer C37 1/4" 2-track-

Started replacing a bunch of old, stressed power supply parts (capacitors and rectifiers).

Finished 54 DI Boxes, thanks to Jon knocking them out the last several weeks. Several dozen left to go.

Finished 8 preamps. Thanks to Brian knocking out the board stuffing so well, it was smooth going.
Finalizing the little post card packing insert.

RCA 74Jr-

Low or distorted level.

This is the problem guy from before, but tested fine in the shop. Retightened ribbon hold down screws and poked around with it to try to get it to misbehave. It only worked.

Royer 121-

Distorted sounding.

Ribbon is stretched. Off to Royer...

Update: 8.28.24
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