This 414 was my most involved and possibly most challenging repair to date. In the process, I decided that only the unusual repairs are worth chronicling. There’s not a lot to say about the typical clean and service jobs.
This machine was incredibly dirty when I received it, and the tape door was hanging off. The faders cut in and out. The Line/Mic 1/4″ in for channel 1 didn’t work, and neither did the Left XLR input. The Line/Mic 1/4″ input for channel 3 cut in and out.
Luckily, the door wasn’t broken and just needed to be reattached. That was a welcome relief. I found a burnt resistor (R101) on the channel 1 input, and one half of U101 (NJM2068LD) was blown based on voltage readings. I started looking around for a replacement or pull for U101, and pulled the resistor for R101 from a Porta 03 parts machine. I came across an NJM2068 in a SIP9 package and set out to find the datasheet for the pinout to see if I could make it work. I relied on the internet sleuthing of a friend to find it, and I was able to make it work. The SIP9 came from a Fostex X-26 parts machine that I have.
The fix for the channel 3 input was something entirely different, and a bit easier. The Jalco jack was cracked so the 1/4″ plug didn’t always make a solid connection. I swapped it out with a pull from the same X-26 that I got the NJM2068 from.
Like the channel 1 1/4″ input, the BALMIC board also had a blown op amp, U102. I can’t imagine what kind of signal sources the previous owner attempted to input into this poor machine. U102 on the BALMIC board is an NJM4565LD. I was able to pull a working one from a Porta 02 parts machine that someone had really mangled in an attempt at repairing before I received it, but that’s a different story. After replacing U102 on the BALMIC board, the Left XLR input worked again.
Wow and flutter was really low on this machine once I was done with it at .05% RMS. It was fully cleaned, calibrated, and tested as per my usual procedure. This machine sold on Reverb in 2 hours.