Yamaha PM2000 external PSU caps

[Ike Zimbel]

If the lights have been flickering, and you've lost everything on those channels, the issue is the power supply wiring to those channels. I can't recall if the power supply busses across the same way that the audio busses, or if they ran separate wires to the backplane boards (or groups of 4 boards...). Either way, that's where to look. BTW, the "staples" are just pieces of bus wire, they just happen to have been bent to closely resemble a staple in size.

 

[JW]

Every time I move my pm2k I like to check the +/-24V rails reach all the way to track 1 before I plug any channels in. Have had a couple bad connections on the backplane. I think it was on GS that somebody said to simply replace the "resistor leg" connections or "staples" as it were, with flexible little wires. I will never do this because it would obviously be a legendary PITA. When you have your console where it's going to be for good, just re verify that the backplane is good and forget about it. It's strange you had to dig down into the pcb trace to get a good connection though. Usually just reflowing does the trick.

As for the JLM eq mod, I once did 24 channels of it. I sold that console, somehow wound up with a second, and decided not to do that mod on any of my current channels. The eq is pretty aggressive sounding, and the JLM mod doesn't really change that. It does widen the mid bands, but I've moved onto digital eq's and my 4 80b rack eqs.

Just FYI, but all incidents where I have had insane white noise and pops on channels have turned out to be opamps, the DOA's or the Hitachi IC's. It's usually easy to find by running program material through the channel, attach a crappy speaker with a capacitor inbetween, to the output of one opamp, then another until you find where it changes dramatically, comparing to a known working channel. You can narrow it down first with the input switch. The mic pre DOA clicks in around noon on the switch. You can hear if it's bad at the point. Similarly, if it's in the eq, you can usually get it to pop and fizz by arming the eq and adjusting the bands until you find the right IC.
Anyway, for anyone reading this in the future, they have been a problem for me, but aren't hard to find other than the fact that pops/noises are often intermittent.

For DOA replacement, I like the Hairball 990's and Pierre's APP992.

After working on this console off and on for almost 20 years, I have a bunch of opinions. But I think the best bang for the buck if someone were to do nothing else, is to pick a pair of program channels, upgrade both the IC opamp (pita) and the program DOA (to 990) and pick a pair of clean high headroom output transformers (originals are still pretty good though) This will take a bit of the blanket off.

Anybody with one of these consoles notice the very mild roll off? Starts around 1K and is down about -2dB at 18K.

 

[RoadrunnerOZ]

It's strange you had to dig down into the pcb trace to get a good connection though. Usually just reflowing does the trick.

The PCB tracks do erode over time if the console has been in a high humidity setting. I’ve 9/10 finished working on one, getting it going after being in storage in a damp garage with concrete floors, and reflowed every solder joint and junction on the backplane boards - some of the junctions I had to flat scrape back the print surface and bridge with new wires. Last issue I have is a random “pop” in the even number master/matrix outs - that’s going to be hard to track down as it only occurs randomly.

I can't recall if the power supply busses across the same way that the audio busses, or if they ran separate wires to the backplane boards (or groups of 4 boards...).

Continuous run across the backplane

 

[Ghaleon]

Finally getting around to this! Seems like theres a lot of issues around the middle of the backpane, so I'll be focusing on that. Scaping back the print surface and adding a touch more solder.

Also a nagging issue: Channel 22 has intermittent crackling/noise. Dosent matter if the channel is engaged or not, noise is present when any PRG button is selected. Post fader, noise is also on FB1, echo 1, FB3, FB4. Things sound clean pre-fader.

 

[JW]

Sounds like the second DOA. Intermittent crackling noise very common for a bad opamp.

 

[RoadrunnerOZ]

I’d be going over the board with an iron and also check switches for intermittent operation but sounds like IC10 - the NE80100.
Quick question - are FB2 and Echo 2 clean and all others noisy? You didn’t list them above as noisy but they should be if the 80100 (IC10) is generating the noise. They all share a common point after the 10Ω resistor following the 100uF cap on output from IC10

 

[Ghaleon]

Success with the backpane Will take a stab at the input modules next, cheers guys