PM1000 Capacitor List for re-cap project - look ok?

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PM1000 Capacitor List for re-cap project - look ok?

Post by Recycled_Brains » Thu Apr 15, 2021 9:56 am

Hey all,

I know this PM1000 shit has been the focus of a zillion threads online, but I can't seem to find a more detailed list of suitable cap values to use as replacements for stock values.

Would any of you who know more than me about this stuff be willing to double check my list and see if everything looks ok? Most of them are direct replacement values, but for some I couldn't find matching voltage ratings so I want to make sure I'm not gonna fuck something up.

Here is a link to my Google Sheet (hopefully it makes sense) - https://docs.google.com/spreadsheets/d/ ... sp=sharing

Also open to suggestions for values to alter the EQ into something more useable. I'm new to this desk, but the EQ is not great as-is, IMO.

In my BOM on Mouser, I selected WIMA MKS for tant replacements, Nichicon UKA series for electrolytics.
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Re: PM1000 Capacitor List for re-cap project - look ok?

Post by digitaldrummer » Thu Apr 15, 2021 10:38 am

I still have everything here -- https://digitaldrummer.net/pm1000
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Re: PM1000 Capacitor List for re-cap project - look ok?

Post by digitaldrummer » Thu Apr 15, 2021 10:45 am

UKA's look good. different than I used but they keep changing models all of the time. For voltage, just make sure you choose something equal or higher. So if it says 50V, and you get 100V, then no problem as long as the physical size is not too big for the location. You are replacing 30+ year old caps so in most cases the new caps will be much smaller diameter (or shorter).

Mike
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Re: PM1000 Capacitor List for re-cap project - look ok?

Post by Recycled_Brains » Thu Apr 15, 2021 10:50 am

EDIT: you answered my question while I was typing this. Thank you!
digitaldrummer wrote:
Thu Apr 15, 2021 10:38 am
I still have everything here -- https://digitaldrummer.net/pm1000
That's what I've been working off (thank you). My concern is just that in some instances, the voltage rating of several of the caps that I found is higher than what is on your chart.

For example, the tantalums are all 35v according to your chart. A bunch of folks, including you IIRC suggest replacing those with WIMA MKS. I was only able to find those rated at 63v at the correct capacitances. I want to make sure that that is an OK substitution.
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Re: PM1000 Capacitor List for re-cap project - look ok?

Post by Recycled_Brains » Thu Apr 15, 2021 10:52 am

digitaldrummer wrote:
Thu Apr 15, 2021 10:45 am
UKA's look good. different than I used but they keep changing models all of the time. For voltage, just make sure you choose something equal or higher. So if it says 50V, and you get 100V, then no problem as long as the physical size is not too big for the location. You are replacing 30+ year old caps so in most cases the new caps will be much smaller diameter (or shorter).

Mike
Thanks man. I've been staring at your website for a few days now! ha. Good shit.
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Re: PM1000 Capacitor List for re-cap project - look ok?

Post by digitaldrummer » Thu Apr 15, 2021 10:56 am

Wima is good and I have also used the Panasonic ECW Poly caps - something like -- https://www.mouser.com/ProductDetail/Pa ... GX8w%3D%3D
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Re: PM1000 Capacitor List for re-cap project - look ok?

Post by The Scum » Thu Apr 15, 2021 1:09 pm

I've got a similar set of lists somewhere. I'll track them down tonight and doublecheck yours.

The unmentioned parameter is lead spacing - that's the critical thing to doublecheck.

There's one of those tant caps that's really under valued (coupling cap coming out of the fader buffer?) and about the biggest benefit you can get is from upping the value.

If you can't find exact voltages, get the next larger voltage, but don't go crazy. Putting a 63V in for a 50V is fine, putting a 200V for it is non-ideal. Electrolytic caps need DC bias in the neighborhood of their rating to reach their rated capacitance, and higher voltage caps are typically larger than lower voltages ones for the same value.

I also had some notes about updating the transistors to newer Toshiba/Hitachi ones.

There are some Jim Williams threads floating around (here and at the purple board), but it takes a lot of reading & interpretation to get anything actionable.

I've played with revoicing the midrange EQ, but don't have a solid recommendation. There are people who swap caps to put them at frequencies that are listed on a 1073, but they don't do anything to match the bandwidths of the 1073, which is where the magic is. The PM1000 midrange Q's are really narrow, the 1073 are really broad.
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Re: PM1000 Capacitor List for re-cap project - look ok?

Post by Recycled_Brains » Thu Apr 15, 2021 7:09 pm

The Scum wrote:
Thu Apr 15, 2021 1:09 pm
I've got a similar set of lists somewhere. I'll track them down tonight and doublecheck yours.

The unmentioned parameter is lead spacing - that's the critical thing to doublecheck.

There's one of those tant caps that's really under valued (coupling cap coming out of the fader buffer?) and about the biggest benefit you can get is from upping the value.

If you can't find exact voltages, get the next larger voltage, but don't go crazy. Putting a 63V in for a 50V is fine, putting a 200V for it is non-ideal. Electrolytic caps need DC bias in the neighborhood of their rating to reach their rated capacitance, and higher voltage caps are typically larger than lower voltages ones for the same value.

I also had some notes about updating the transistors to newer Toshiba/Hitachi ones.

There are some Jim Williams threads floating around (here and at the purple board), but it takes a lot of reading & interpretation to get anything actionable.

I've played with revoicing the midrange EQ, but don't have a solid recommendation. There are people who swap caps to put them at frequencies that are listed on a 1073, but they don't do anything to match the bandwidths of the 1073, which is where the magic is. The PM1000 midrange Q's are really narrow, the 1073 are really broad.
Thank you! This is good stuff. I did not think about lead spacing too deeply, so I appreciate that. I read SO many threads everywhere. I bookmarked a lot of it and read through them a few times and took notes of certain simpler mod ideas. Seems like C37 is the infamous one. Bump it to 220 or 330.

Jim Williams likes swapping the transistors. I'm not looking to clean up the sound too much. I dig it. I just want to make the more sensible improvements and make it more reliable. The power supply already had an overhaul, so that's nice.
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Re: PM1000 Capacitor List for re-cap project - look ok?

Post by digitaldrummer » Fri Apr 16, 2021 6:24 am

if you do end up replacing any transistors, it gets a bit tricky because the packaging has changed, so you have to rotate them and twist the legs a bit so they match the right holes - if not then you will let out the magic smoke).

also, go easy on the solder iron heat (as much as you can) when de-soldering or you may lift the solder pads. the boards are also 30+ years old.
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Re: PM1000 Capacitor List for re-cap project - look ok?

Post by The Scum » Sat Apr 17, 2021 11:13 am

I'm not finding the notes I used to generate mt BOMs, but I've got my assembly sheets to check against.

I see the following:

7x 47/50
2x 47/35

5x 33/25 - you have 4

5x .47/63 - you have 4 - originally tantalum, I swapped to 1.0 panasonic film caps.
1x 1/35 - tantalum, swapped to film
1x 3.3/35 - tantalum, swapped to film. the 3.3 film cap is giant, but there's plenty of space over there.

2x 3.3/25 - I had to swap to 50V

4x 4.7/50 - swapped 50V for both 25V and 35V

2x 100/6.3 - missing on your list
1x 10/35 - missing on your list

I also put little film caps (0.1u? 0.01u?) in parallel with the 47/50's.

C37 is indeed the troublesome one - originally 33/25 - swap to larger value (100, 220, 330, etc) if possible.

Transistor swaps - I used Hitachi 2sa1084's and 2sc3329 (Hitachi, Toshiba respectively). Pinouts match the originals (Both are ECB). Either came from BDent, or Futurlec.
Swapping transistors lowers the noise floor, it doesn't change the distortion characteristics much.

A couple tricks I used: I'd count out one strip worth of caps into compartments on a muffin pan, then go through the strip and put a dot of dollar-store fingernail polish on every component to be swapped. Helped me keep track as I went - I shouldn't be removing parts without the dot, and shouldn't have any dots left when I was done.

Also, to keep from lifting PCB traces, it's typically better to work hotter & faster - lingering heat is what does the damage. Get a flux pen to help make the solder flow more quickly.
Last edited by The Scum on Sat Apr 17, 2021 11:56 am, edited 1 time in total.
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Re: PM1000 Capacitor List for re-cap project - look ok?

Post by The Scum » Sat Apr 17, 2021 11:44 am

Also, find yourself a source of the little screws that hold the backplate on the modules (M3?). You will strip a number of them in the process.
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Re: PM1000 Capacitor List for re-cap project - look ok?

Post by digitaldrummer » Sat Apr 17, 2021 3:12 pm

if you need any screws, knobs, etc. I still have tons of that stuff.
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Re: PM1000 Capacitor List for re-cap project - look ok?

Post by The Scum » Sat Apr 17, 2021 3:35 pm

I seem to recall you sent me a care package with some of that stuff years ago!

I could always use a few more of the male 28-pin connectors, to make service harnesses...
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Re: PM1000 Capacitor List for re-cap project - look ok?

Post by Recycled_Brains » Sat Apr 17, 2021 3:42 pm

You guys rule!

Thank you. I really appreciate it.

I'll keep you posted.
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Re: PM1000 Capacitor List for re-cap project - look ok?

Post by Recycled_Brains » Tue May 11, 2021 12:00 pm

Got one channel done (bttm). I did a very un-scientific A/B between it and a stock module. Just played a riff over and over, used a splitter to send to each channel, gain matched, etc. The difference isn't terribly subtle. EQ seems like it's probably a lot better. More clarity, but still pretty dark and hairy sounding. Looking forward to doing more comparisons

I'm going to do 7 channels more over the next few weeks.

Image
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