Recapping - Can I substitute screw terminal for radial through hole?

[jdurango]

Recapping a Power One HDD15-5-A (schems attached) for a Sound Workshop Series 40 console. Several SW techs have recommended increasing capacitance on PSU caps by roughly 10x, which means stepping up to screw terminal caps, from the stock radial/through hole caps. There's plenty of room in the chassis to mount these in their own little area. But how would I run the wire back to their old home on the PCB? Is there some type of header or pin or adapter I should use? Or just shove the thickest gauge wire I can fit in there and solder it as cleanly as possible? Thanks fellas!!

 

[radardoug]

Ten times the cap??? Watch those diodes pop! You can do it, but in the process you are saying that the Power One engineers didn't know what they were doing. Very unlikely. On the other hand, if you are an experienced power supply designer, go for it.
Its like saying I can bore out my chevy motor and make it run better. Good luck with that!

 

[Khron]

Were they having trouble with ripple on the supply rails? Even so, not sure how much bulk filtering might help with that, if the load (where the issue crops up) is at a distance.

... But i see the supply rails are regulated, so adding extra capacitance in the C1/C2 positions won't help with anything, and in the C6/C11 positions it'll only put more intial stress on the pass-transistors as well, as power-up inrush (when capacitors are discharged, especially big ones, they act as short-circuits until they charge up).

Some added local filtering might potentially help, or even "just" refreshing the (possibly) ancient capacitors in there, but the initial idea is a bit of a "shotgun approach", at best. More like "ICBM approach", rather...

... Buuuuuut if you're having some sort of grounding issue that's causing hum, a 10-fold increase in power supply capacitance won't do squat for that. If anything, it might even make it potentially worse.

 

[Audio1Man]

“If it isn’t broke don’t try to fix it.”
My answer to randomly replace all capacitors with new ones is DON’T DO IT. Too many DIY are not qualified to know what needs to be replaced and when they do the device fails to work correctly after replacements.

As for 10x value for new caps the Rectifier, Switch, Connectors, PCB traces and Fuse are high on the failure list after doing this.

 

[pucho812]

“If it isn’t broke don’t try to fix it.”
My answer to randomly replace all capacitors with new ones is DON’T DO IT. Too many DIY are not qualified to know what needs to be replaced and when they do the device fails to work correctly after replacements.

As for 10x value for new caps the Rectifier, Switch, Connectors, PCB traces and Fuse are high on the failure list after doing this.

shotgunning parts is never the correct answer.  unless of course they all have failed. I am finishing up a recap on  set of electronics for a plate reverb. Long story short, every cap in the PSU measures as leaking and or dead according to my cap tester.  I know why they have failed as well, years of no preventative maintenance.

 

[Brian Roth]

There are no parts values in the schematic.  Out of curiosity, what are the values of the main filter caps?

 

[jdurango]

There are no parts values in the schematic.  Out of curiosity, what are the values of the main filter caps?

Main flter caps are 23000uF. Thanks Brian!

 

[Brian Roth]

What Voltage rating?  I'm guessing at least 25 VDC...probably higher.  Have you looked at "snap in" capacitors, which are basically a radial style with much shorter leads?  They might fit on the existing circuit board.  I see some possibilities at Mouser, but you'll need to check diameter/height/lead spacing.

Bri

 

[Khron]

Highly unlikely. Radial caps usually top out at 7.5mm pitch and 0.8mm(?) lead thickness, while snap-ins are 10mm pitch and need 2mm holes or so.

Granted, still easier to mount that screw-mount caps, but you'd still require some PCB "reworking" and creativity...

Have you looked at "snap in" capacitors, which are basically a radial style with much shorter leads?  They might fit on the existing circuit board.  I see some possibilities at Mouser, but you'll need to check diameter/height/lead spacing.

Bri

 

[CJ]

Nichicon makes some nice caps with solder lugs, KG series, audio grade, expensive,  good quality,  nice bass,

gonna need some clamps,

https://www.partsconnexion.com/capacitors-ele-nichicon-kg-series.html

 

[Brian Roth]

I am now wondering if PowerOne/etc. were actually using "snap-in" caps (which look pretty similar to radials).  I now that on some of their Big Dogs, like 5 VDC at 25 Amps, they were using screw terminal caps.  Those had clearance holes on the chassis beneath the PC board for clearance of  the screws.

Bri

 

[jdurango]

What Voltage rating?  I'm guessing at least 25 VDC...probably higher.  Have you looked at "snap in" capacitors, which are basically a radial style with much shorter leads?  They might fit on the existing circuit board.  I see some possibilities at Mouser, but you'll need to check diameter/height/lead spacing.

Bri

Sorry, spaced the voltage...23000 uF 35v. Thanks again! Snap in would work as long as the spacing is correct. The caps themselves are about 2.5" diameter, not sure on spacing. I could pull them out, but I'd rather have the new caps ordered and ready to pop in before I start pulling stuff apart as I'm doing other work on the console that requires it to be turned on.

 

[Khron]

At that value and voltage rating, odds are good it's already the snap-in variety. remains to be seen whether it's the two-legged kind, or some "fancier" 3-4 legged kind (for added mechanical security).

"Plain" leaded radials (at least modern ones) seem to top out around 4700uF at 35v.

 

[jdurango]

At that value and voltage rating, odds are good it's already the snap-in variety. remains to be seen whether it's the two-legged kind, or some "fancier" 3-4 legged kind (for added mechanical security).

"Plain" leaded radials (at least modern ones) seem to top out around 4700uF at 35v.

Gotcha! I'll see what I can come up with in the snap-in catalog! Thanks Khron! Much appreciated!

 

[jdurango]

Also, to reply to some of the other folks, this is not "shotgunning parts" to fix a specific problem. This is standard PM. You may not believe that recapping a 40+ year old piece of equipment is a wise investment to achieve the best operational reliability and sonic performance possible. That's fine, I do.

Also, I'm not second guessing the Power One designers. Power One didn't design this power supply specifically for the Series 40. Sound Workshop used these same generic Power One modules on a lot of their consoles, and the Series 40 happened to be one of the largest utilizing this PSU. Many original SW engineers have said SW cut costs by using smaller caps than were ideal in many parts of the circuitry, including the power supplies (as well as going with cheapo TT patchbays). Many SW techs and engineers in the SW Yahoo Group recommend upping the values on caps of these consoles, and many have reported great results after doing so.....although I agree that I can't think of a scenario where a 10x increase wouldn't be overkill.

The most compelling advocate of using the largest value caps possible (generally speaking) is Steve Hogan of Alpha Dog Audio and former VP of engineering @ Jensen who makes his case in the Sound Workshop group thusly:

"Let me explain how and why I choose the caps I choose to recap any piece of audio gear, including consoles.  The better you understand the “why” the easier the “how” will come to you.

1.  Every power supply electrolytic cap stores energy for use by the circuitry it services.  The bigger the cap, the more energy is available for low frequencies and the less crosstalk. The caps should be polarized (oriented correctly), and at least 25V.  Using 16V rated caps on Bipolar 16 Volt rails runs the caps too close to the edge for long, trouble-free life.  The higher voltage caps have less dissipation factor and sound better.  Use 105C high quality caps.  I like Panasonic FM or FC here.  Use 470uF if they fit, otherwise 220uF, and 100uF only if the larger values can’t be made to fit.

2.  Series audio coupling caps not associated with High-Pass EQ are there to eliminate DC offsets from stage to stage and to prevent clicks and pops when switching.

If you replace certain opamps with better ones with less DC offset, sometimes you can replace that cap with a jumper.  This is the best-sounding cap you can get (none).

Every cap in series with the audio causes a loss of Low Frequency magnitude and along with that, a phase shift that can easily affect the midrange clarity.  This is most easily seen by feeding a 20Hz square wave into the input and using a DC-coupled scope to monitor the waveform “before” and “after” each capacitor.  The tilt will increase “after” every cap.  The larger the value of the cap, the less additional tilt (phase shift) will be introduced into the chain. Ideally, at the end of the chain, the 20 Hz square wave will still look very square with less than 25% tilt.  In most consoles, the waveform is unrecognizeable as a square wave.  The tilt is so bad that it looks like a distorted sawtooth. Often, a 100Hz square wave has about the same amount of tilt that you should be getting from a 20Hz square wave.  100Hz should have virtually no tilt (less than 5%). You will often discover by using this “scope” method, that some caps are severely undersized, and those will show a big increase in tilt “after” compared to “before” the cap.  You will make a HUGE improvement by finding those “bottle-neck” caps and replacing them, even if you can’t afford to replace all the caps in the signal path.  Undersized caps that introduce excessive tilt to the 20Hz square wave also will be introducing excessive THD at the same time.

In audio gear using bipolar supplies the DC offsets are small and random in polarity.  Therefore audio coupling caps should be NON-POLAR.  Non-polar caps were not used originally because they cost more than polar caps and they are bigger physically.  They have lower THD than polarized caps used in this application.  I typically use 100uF/25v, 220uF/25V and 470uF/25V caps to recap 95% of audio gear.  The size is determined to minimize LF loss (20Hz square-wave tilt as discussed above).  The amount of loss is determined by the worst-case LOAD on the capacitor.  That’s why it is important to analyze the schematic carefully to determine the load on each cap in order to determine the correct value in each position in the circuit.  Caps that feed the pan-pots and lots of 10K aux send faders are usually bottleneck caps.  Remember that four 10K aux send faders present a 2.5K load to the cap.  Pan-pot circuits often go below 1K especially when rotated to one side.  470uF is required here to prevent massive low-frequency losses and resulting phase-shift.  I have used Panasonic SU mostly, but the green Nichicons are very good sounding.

My “rule-of-thumb” is:

Use 100uF for 10K or higher loads.

Use 220uF for loads from 3-5K to 10K

Use 470uF for loads from 600 to 3K.

Use multiple 470uF in parallel for loads less than 600 Ohms.

For mic inputs you should use 63V (not 50V) POLARIZED caps and you should make them not less than 220uF.  More is better.  Make sure your phantom circuitry is modified to handle modern, power-hungry transformerless mics, or they will be power-starved and sound BAD.



If you don’t read schematics well enough to determine the load on each cap, hire someone who does to help you figure out which cap is the correct one for each location in the circuit – it will pay off in spectacularly improved sound quality from your console.

IT is a LOT of work to properly recap any console. The cost of the best caps (Panasonic and Nichicon – Non-Polars where appropriate) over cheap Xicon crap is very small

compared to the many hours of labor required to properly remove and replace the caps.  Spend the money on a very good vacuum desoldering gun like the Denon.  It is expensive ($450.00), but you will be replacing hundreds of caps, and it makes the job almost pleasant compared to destroying your circuit boards with hand operated desoldering tools and solder wick.

Hopefully this tutorial will help clear up the massive confusion and internet mis-information that abounds out there about re-capping consoles.

Steve

Steven A. Hogan
The Sound Steward"

 

[radardoug]

So he is talking about changing audio coupling caps and supply bypasses. Nowhere does he suggest increasing the power supply caps from 23,000 uF to 230,000 uF. Thats almost 1/4 of a Farad!
Some of what he says makes sense, some doesn't.

 

[Steve Hogan]

I appreciate the long re-post of my tutorial on Console recapping.
After re-reading my post from many years ago, I still agree with what I wrote.  However ...
When I was speaking of power supply caps,  I was speaking of bulk ps decoupling  caps on each module,  not the main regulated power supply  feeding the console.  The console caps in the SW boards were notoriously undersized.

I would NOT recommend 10x increase in value for the bulk filter caps in your main power supplies.  When I hot-rod Open frame LM-723-based commercial power supplies, I typically would go 1.5x to  3x the original size.  Larger causes unintended consequences such as higher initial inrush (hard on the rectifiers), much shorter filter capacitor charge time and therefore much higher peak currents in the transformer-rectifier-caps-transformer loop.  These higher, shorter high current pulses can worsen IR drops in the supply pcb layout increasing ripple induced hum.  The transformer can put out more magnetic interference due to the increased pulsing currents.

The commercial LM-723 based power supplies  can be made to have better performance, but not by simply making the bulk caps bigger.    Often the 723 is overcompensated.  The fix is generally in fixing pcb layout issues and reworking the regulator circuitry.

 

[Khron]

... So it wasn't just my imagination, then.

Some of what he says makes sense, some doesn't.

And my earlier points have just been confirmed.

Were they having trouble with ripple on the supply rails? Even so, not sure how much bulk filtering might help with that, if the load (where the issue crops up) is at a distance.

... But i see the supply rails are regulated, so adding extra capacitance in the C1/C2 positions won't help with anything, and in the C6/C11 positions it'll only put more intial stress on the pass-transistors as well, as power-up inrush (when capacitors are discharged, especially big ones, they act as short-circuits until they charge up).

Some added local filtering might potentially help, or even "just" refreshing the (possibly) ancient capacitors in there, but the initial idea is a bit of a "shotgun approach", at best. More like "ICBM approach", rather...

... Buuuuuut if you're having some sort of grounding issue that's causing hum, a 10-fold increase in power supply capacitance won't do squat for that. If anything, it might even make it potentially worse.

When I was speaking of power supply caps,  I was speaking of bulk ps decoupling  caps on each module,  not the main regulated power supply  feeding the console.  The console caps in the SW boards were notoriously undersized.

I would NOT recommend 10x increase in value for the bulk filter caps in your main power supplies.  When hot-rod Open frame LM-723-based commercial power supplies, I typically would go 1.5x to  3x the original size.  Larger causes unintended consequences such as higher initial inrush (hard on the rectifiers), much shorter filter capacitor charge time and therefore much higher peak currents in the transformer-rectifier-caps-transformer loop.  These higher, shorter high current pulses can worsen IR drops in the supply pcb layout increasing ripple induced hum.  The transformer can put out more magnetic interference due to the increased pulsing currents.

 

[PRR]

...I'm not second guessing the Power One designers. Power One didn't design this power supply specifically for the Series 40. ....

Power One and Acopian fought tooth and nail for half a century competing for the power-brick market. (Didn't they merge, or both get swallowed-up?)

Yes, the original design was very sharp-pencil "right size", no fat on the bone. Gave good service powering factory gear for a couple of decades. Occasional replacement is part of the factory serviceman's job.

I can accept that these were just good enough for Sound Workshop when new, and could stand refreshing, and possibly upgrading, in fussy studio work. 2X-3X original cap value seems reasonable to me (it is what I often did; though I once treated a 80uFd Bogen to 470uFd...)

 

[jdurango]

I appreciate the long re-post of my tutorial on Console recapping.
After re-reading my post from many years ago, I still agree with what I wrote.  However ...
When I was speaking of power supply caps,  I was speaking of bulk ps decoupling  caps on each module,  not the main regulated power supply  feeding the console.  The console caps in the SW boards were notoriously undersized.

I would NOT recommend 10x increase in value for the bulk filter caps in your main power supplies.  When I hot-rod Open frame LM-723-based commercial power supplies, I typically would go 1.5x to  3x the original size.  Larger causes unintended consequences such as higher initial inrush (hard on the rectifiers), much shorter filter capacitor charge time and therefore much higher peak currents in the transformer-rectifier-caps-transformer loop.  These higher, shorter high current pulses can worsen IR drops in the supply pcb layout increasing ripple induced hum.  The transformer can put out more magnetic interference due to the increased pulsing currents.

The commercial LM-723 based power supplies  can be made to have better performance, but not by simply making the bulk caps bigger.    Often the 723 is overcompensated.  The fix is generally in fixing pcb layout issues and reworking the regulator circuitry.

Hey Steve, thanks for the reply! So just to clarify, you'd generally recommend:

- Up values 1.5-3x on the main recitifer caps in the PSU. So in my case, around 50,000-75,000uF.
- Much larger values (as big as one can reasonably fit?) on the decoupling caps in the channel strips/master section.
- Use quality polarized caps for decoupling duties, such as Panasonic FM.
- Use quality bipolar caps for coupling, such as Nichicon ES "Muse" or Panasonic SU. (What about values on these caps? Keep them the same? Up voltage? Capacitance?)

Any strategic places you'd recommend film caps for coupling without increase noise too much? Or film caps in parallel with lytic? Thanks Steve! Very much appreciated!!