PM2000 rebuild, part 2

September 26, 2014 -Finally got the capacitors swapped out. Turned out to be about 800 of them. Yamaha decided to use a very aggressive epoxy to hold them on. Each one had to be loosened with a dental pick before I could desolder. Next step was to perform surgery with a Dremel tool on the spare headphone PCB. I need just the small part to convert the mono CUE and TB output into a stereo Control Room output. Lastly I’m ordering parts and trying to figure out where to fit this Midas AD/DA FireWire circuit board. It’s a little bigger than I suspected.

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September 30, 2014 – So I spent a few days polishing my knobs. Sorted out the cracked and damaged ones. Glad I have a bunch of spares. I have swapped most of the capacitors and LEDs. Today I decided to take a break and work on a shielded case to mount the FireWire card under the meter bridge. I striped a pair of channel frames down to bare metal and cut them into a mating rectangle, reusing existing screw holes and brackets. Marked off where to weld them and proceeded to make a bunch of quite ugly welds. I hate welding. They cleaned up ok but didn’t break. A little jb weld to fill the crevices should finish them nicely. The brackets fit the holes with a little tweaking. I’ll wrap the back and side with aluminum tomorrow, then mount everything in the console. And possibly work out the power supply requirements.

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October 8, 2014 – The headphone amp contained the last few capacitors that needed replacing. Then it was time to do some testing. I need to verify that the OPA604 opamp swap works without oscillation or distortion. While prepping for that, I decided that the even after recapping, the stock headphone amp was too noisy. Quite a lot of hiss. So I decided to mock up a replacement using a pair of Texas Instruments INA217 Instrumentation Amplifiers. While I was at it, I made a stereo unity buffer for the monitor controller and a power supply for the Midas circuit board. +/-18vdc, +5vdc & +3.3vdc with regulation and filtration. Lots of solder today.

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October 9, 2014 – Finally got some serious testing done. Among other things that worked out well, the OPA604 opamp swap was a success. I used Rightmark Audio Analyzer to monitor a 1kHz sine wave in both Oscilloscope and RTA modes. As I increased gain beyond clipping, there was less high frequency distortion as compared to stock. As you can see on the screen display the green numbers are the new opamp, the red numbers are the old opamp. Then I played some music thru them and it’s a noticeable improvement in tonality and detail. I can’t wait to mod all of the summing busses. Ordering parts tonite. I finished building and tuning the power supply for the Midas. It’s ready for a case. Then I figured out I could modify one of the 11 position gain switches to be used as a control room source selector. Since it was a live mixing console, there were very limited monitoring options. In order to use it in a recording studio, you need to be able to monitor any of the output busses. That’s 4 stereo Program busses, 4 stereo Matrix busses, 1 Cue bus and 2 stereo Tape Returns. There’s just enough room beside the meters to fit the controls.

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25 Comments Add yours

  1. Barry Milholen says:

    Pretty awesome stuff going on here. Impressive!!!!

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  2. Craig says:

    the BB OPA604 says max 18v…is this ok to place in the pm2k?

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    1. flyingeyepro says:

      The Texas Instruments site lists the max power as +/-24vdc. I’ve got 18 of them installed so far with no issues. Lower noise and better detail.

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      1. Craig says:

        Thanks so much….do you feel the adapter board is necessary on the HA1457? I’ve seen a pm700 mod that used an opa134 and just used heat shrink on the leads and soldered direct to the PCB. Sorry to bug you but man, you’ve done one hell of a job on your console! We have recapped the whole board and PSU, my son has built me 2 hairball audios DOA’s and I’m looking to further improve the board. If you had to do over, would you still use the 604? I see there are 8 HA1457 per input channel… (3 on the eq), did you consider replacing any of these?

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      2. flyingeyepro says:

        I thought of using wire and heatshrink,but the PCBs I found on eBay are extremely cheap and make assembly faster. Also, the power supply bypass caps (0.1uf) are needed. I verified that the OpAmp will oscillate if they are not installed very close to the OPA604. I do intend on replacing all the OpAmps in a pair of channels as soon as time allows. I’ll post more pictures asap.

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      3. Craig says:

        That would be great and thanks for posting…I have the 32ch as well, that means about 180 opa604’s or $400! Ouch… It sounds like it’d be worth it thou. Check out this link https://www.gearslutz.com/board/low-end-theory/373941-yamaha-pm700-direct-outs.html?highlight=opa134

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  3. Juan says:

    Wow this is amazing!!! Great work! I have one as well and would like to replace the lightbulb on each channel. Could you let me know which ones you used and where I can buy them? Any info would be greatly appreciated thank you!

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    1. flyingeyepro says:

      I purchased 5mm soft white LEDs off of ebay. They come with a current limiting resistor, I ordered mine with the correct value for 12VDC. There are many LEDs to choose from. After removing the original bulb, I also removed the large 1W resistor behind the switch. I rearranged the wires on the PCB to allow the incoming voltage to pass thru the channel switch. One modification I found necessary was that the 5mm LED is a little too small for the bulb grommet. A short piece of heat shrink tubing solved the problem. I changed the Meter bulbs also and eliminated on of the voltage rails. All of my LEDs run on 12VDC. If you use the stock power supply, the Channel On bulb voltage is 16VDC and the Meter bulb voltage is 10VDC, requiring 2 different resistor values.

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  4. Juan says:

    Thank you very much. This was very helpful, I have replaced a few LEDs so far!! It’s working great.

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  5. Jon says:

    Hey,
    What a great blog about the PM2K. I thought I’d share the following info if you haven’t come across it. The mid eq’s on the PM2000 can be improved considerably using the following mod kit:
    http://www.jlmaudio.com/shop/index.php?_a=viewProd&productId=60

    Unfortunately it gets a little expensive if you’re doing the whole board. So I ordered one of these and cloned it, sourcing the parts myself and actually hack sawing up a bunch of radio shack perf boards to mount them on. A very useful and noticeable improvement with the fully inductive (and wider) mid bands.

    Also, I ended up sacrificing two of my program outs to put this guy in there. It’s a recreation of an API summing buss. It sounds pretty stellar. The originals aren’t too bad either though. http://classicapi.com/catalog/product_info.php?cPath=22_46&products_id=403

    Anyway, I have a couple questions too. I’d definitely be interested in trying to replace the old chip IC’s. I think first you made a mockup of the adaptor boards, but then ended up buying some off ebay? Do you have a link to those? Also, I think you might be able to bypass some of the DC blocking caps, now that you have the modern opamps in there. Though, my understanding at that point is not enough to know which ones.

    Also, do you know if those opa chips draw more current? I’m trying to figure out how to do this without having to build a new power supply (which I’ve actually already done with two gigantic Power One power supplies, but they’re physical humming is too audible and I went back to the original power supply, which didn’t really seem much different in sound anyway, but maybe I’m crazy)

    One of the great things about this board is pushing the input a bit by turning the input switch up a couple clicks which you’ve probably already noticed. However, in the context of a mix (at least on my board) that is also when some sources (more sustained ones) start developing that nasty crackly distortion that I’m hoping the IC upgrade remedies at least to some degree.

    Anyway, way to go on all your hard work!

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    1. flyingeyepro says:

      Thank you. I have heard of the JLM mod. I’ve built a similar circuit on perfboard. It’s a great sounding mod I built mine with all shielded inductors and poly film caps.
      I’m glad to see someone installed the CAPI summing boards. Which DOAs did you choose? I also love his direct out transformers. Great sounding at a great price.
      Concerning the OPA604, the typical current draw is 5.3mA while the HA1457 draws 4.7mA. Both values are measured while passing a pink noise just below clipping, averaged. But most only varied by 0.2mA. I doubt the increased current draw would be an issue to a stock power supply, unless you replaced them all. In which case, an Acopian power supply would be a good upgrade. I noticed the Pgm bus upgrade had a more impressive effect than upgrading an input channel. I ended up using a tiny SOIC to DIP adapter, cut a couple traces and soldered in a header. I paid $0.15 each for the PCBs on eBay. There are multiple sellers. JLM and Brown Dog both sell adapter board too.
      I tried bypassing some of the caps, but I actually prefer the sound that resulted from replacing them with nice electrolytics. If money was no object, I would replace all of the electrolytic and tantalum capacitor with high quality bipolar caps like Nichicon Muse BP.
      Concerning your crackling noise. If you trace the signal path thru the mic preamp, you’ll notice that the first five positions of the gain switch (+4 thru -20) bypass the NE80200 discrete opamp, going directly to the first HA1457. The two opamps will distort differently.

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  6. Jon says:

    For the ACA summing buss, I’ve swapped in and out the DIY Melcor’s and 2520’s. I have two of each in there right now. I think I may go back to only 2520’s though. They sound pretty similar to my ears though.

    I’m guessing that first non-discrete IC that you’re talking about (IC2) would probably be the most crucial one in the input strip to try swapping out?

    I spent awhile looking for these mysterious .15 cent adapter boards on ebay, with no luck. hmmmm. . . .

    Concerning chip replacement, it also occurred to me that the mid band JLM mods bypass the two IC’s in the mids? Or maybe not. I’ll have to go check that. Actually it makes more sense that they wouldn’t because the passive eq needs amplification right?
    But if they did, there would be plenty power all around for the opa604’s if I pulled them. Just talking out loud here.

    Funny you mention Nichicon Muse caps. That’s what I’ve used in mine. I did that right away, so I don’t really have anything to compare them with. Nichicon HE’s and PW’s are good too, for the polarized caps. I just tried replacing all the tants in one channel with electrolytics and wima polyester MK2 caps for anything 1uF and below. I think I might go ahead and go whole hog on that mod. Seems to sound a little better.

    Anyway, thanks for the info!

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  7. Jon says:

    Okay,
    Don’t know if you’re still checking replies to this blog, but I’ve been looking for a long time for the little adaptor boards for the SIP opamps. I see them ranging from at the cheapest (about $1.20) to around $2.50 on ebay. Added up, this gets pretty expensive, plus the cost of the 604.
    If you could share who you got them from at .40 cents a pop I’d love to hear about it.

    I did do some direct wiring of a opa604 to IC2, the input opamp, and yes, it’s different and better, I think. I’d like to do a whole channel, but it was a pain in the butt without the adapter board.

    ?????

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      1. Jon says:

        Ah,
        Okay, I can see how those would work, though they don’t exactly have anything to do with the SIP footprint. You have them at a 90 degree angle to the PCB? Just wiring your own leads from both sides of the board?

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      2. flyingeyepro says:

        Yep, two jumpers and you’re in business. I can’t tell if the psu bypass caps are necessary, I add them because they’re easy and cheap.

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  8. Gwen says:

    Hi guys, what a nice blog about the PM2000 !
    I’m just starting a rebuild on mine,
    Did you try to swap the IC1 & IC1O NE80200/80100 for any other references ? thanks
    Gwen

    Like

    1. flyingeyepro says:

      Hi Gwen, I have tried a few opamps. The NE80200 swap has a more drastic impact on the tone. But since it’s only used over about half of the gain range, swapping the next opamp in line, IC2 (HA1457), should be considered. My favorite input channel combo was the Hairball DIY-990 for IC1 and TI OPA604 for IC2.
      I find that swapping the Program or Matrix DOAs have some impact but no where near as much as swapping the Program summing HA1457.

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      1. Gwen says:

        Hi, thank you for your reply. I will definetly consider these Hairball DIY-990 ! About this IC2 swap, i gonna follow your instructions about how to adapt TI OPA604,
        What about this NE80100, what’s the difference with the NE80200 and the equivalence for swap ?
        thank you

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      2. flyingeyepro says:

        Concerning the HA1457-OPA604 swap. You can also make an adapter using the DIP version of the opamp and some breadboard, it will be a little larger and require a little more soldering.
        The specs for the Yamaha DOAs were never published, but from my experience, the NE80100 was designed for higher gain, low noise (like mic preamps), while the NE80200 was designed to drive 600 ohm output transformers. Most DOAs fall in one of these two categories.

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  9. Gwen says:

    Tanks again for your help man,
    Do you have any experience with swaping the output transfos with new references ?
    JLM actually proposes a transfo ref JLM111DC, i was wondering about how significant it would be …

    Like

    1. flyingeyepro says:

      An output transformer swap is usually audible. The stock xmfr is a decent copy of the API xmfr, but certainly not flat or transparent. I would try swapping only a pair and see if you like. The EA 2503 from Classicapi.com sounds very good and are reasonably priced.

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  10. How can I contact you? the work you do is amazing!

    Like

  11. Juan Maldonado says:

    Hello, hope you are well. I am wondering if you are willing to sell some parts? I am need of 6 black input fader caps, 6 red master fader caps, and 3 eq knobs for the gain and frequency selectors. Are you willing to sell me these parts? if so, how much? Thank you in advance.

    Like

  12. flyingeyepro says:

    Hey Juan, email me. Flyingeyepro at Gmail.com

    Like

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