Aleph3 recap

[Dukja]

I just got a Aleph 3 to push a very inefficient headphone (HE-6), so not much room effect in my sonic impression. Up to now I am very happy with the large soundstage and accurate focusing from the 3. However, I wish the mid/upper bass may be tighten up and has some more impact. Also, I wouldn't mind if the midrange get more body.

From what I read here, it seems replacing those 8x 22k caps may help (also consider these original caps really approach its age limit). I have some questions as a newbie here (although I have EE training and did some vintage amp recapping) and appreciate your help.

I opened up the case and found some MOSFET boards attached to the heatsinks have L shape solid wire connected to the PCB with 8 caps. I'd like to know the good procedure to separate them and replace the caps without damaging boards.

Also, I read people use caps with larger capacitance (>22k uF) as upgrade. What is the good value to use if I want to improve in the above mentioned aspect.

Thanks!

 

[Dukja]

No one worked on their Pass Lab Aleph 3 (not the DIY ones)? or is it ?

I read a post from Nelson in 2009 claiming none of the 3 need recap yet. Will two more years change it?

 

[Zen Mod]

hard to say without checking them with ESR meter

regarding other question(s) , well - I didn't worked on original Aleph

 

[Dukja]

Hotter is worse?

Last night I have another listen with Aleph 3. I found out that when the amp was not fully warm up (may be first 1 hr), the sound actually was nicer. After the amp is totally heat up to about 120~130F. I found the high became thinner, midrange recessed, and bass became softer and weaker. So I wonder if this is the sign of any component showing their age? On the other hand, this could be my preamp. So, I'll need to start them at different time to test. Thanks for your insight!

 

[Dukja]

OK, I had more listen with Aleph 3 at hot (~120 F) and moderate temperature (~100F) and could not get firm conclusion that hotter was worse again. So maybe that was just me being picky and play volume was not the same. I also take a good look at the internal of Aleph 3. It seems that I just have to desolder all the while L shape connections (16x) from the MOSFET boards in order to free the PSU board. Anyone could offer a better idea? Also, I couldn't find any internal photos of Pass Lab Aleph3 with Google. Is it OK to post some here for people to give suggestions? Or I am at the wrong place to ask such question? Thanks for any help!

 

[Zen Mod]

post pics ;

or wait that Papa answer on your question

 

[Dukja]

Thanks a lot for the reply. I'll post some photo when I get home and wait for Papa's help if such trivial thing ever catch his eye.

 

[Dukja]

Here is the internal shot:

An externally hosted image should be here but it was not working when we last tested it.

Those L-shaped connecting wire (actually 14 of them) are the ones that I plan to desolder in order to get to the back side of those 22k caps. One thing strike me about Aleph 3 was how compact it has been designed. This "3D" construction make short signal path and use all surface and volume effectively. However, it seems to make fiddling inside a little bit hard (at least for a newbie like me).

Any good idea to replace those caps?

BTW, are those small electrolytic caps on the MOSFET boards the so-called coupling caps? I guess that it is also a good idea to replace those, right?

Thanks!

 

[imix500]

Is it just me or do a few of those caps look bulged?

 

[Dukja]

I think it may be due to optical distortion since I took the shot at rather close distance.

Here is another one with slightly different angle and with more pixels to inspect.

An externally hosted image should be here but it was not working when we last tested it.

I try to feel the top of the cap and them seems to be rather flat to me. But on a second look the middle one at the bottom row does seem to be bulged if we use the plastic wrap around the top of the cap as a guide.

Any more trained eyes would help?

Thanks!

 

[Zen Mod]

just de-solder these L bridges from cap pcb and pull then gently upwards

after that - clean these pads with solder sucker , to prepare them for easier and proper later soldering

use stronger soldering equipment (say 60W) with screwdriver shaped tip - you need more power and fast heat transfer

while re-caping main caps , replace all small ones too

use Elna Silmics - Papa like them

 

[Dukja]

OK, I guess there is no way out. I just have to desolder those connections. Usually I use a good soldapullt to suck out solder and I do have a temp controlled solder station.

I found some Panasonic ones at digikey but have no luck on Elna Silmics one. Anyone could help?

Thanks!

 

[Zen Mod]

I resume that you'll find some 220uF/50V easy

you can also use 470uF/50V instead of 220uF

instead of 50 you can use 63V

there are numerous vendors on-line for Silmics

 

[Dukja]

OK, I guess that you meant
1. using Panasonic or whatever for the 22k uF ones
2. using Silmics for the small 220 uF caps

Is that right?

The 22k uF Silmic caps were the ones that I cannot find quickly. Will the 22k uF Panasonic ones @ digikey work alright? Those are quite affordable ($7~10).

 

[Zen Mod]

sorry , I wasn't clear in first place ....

off course that I meant at Silmics for those little ones

big ones - in PSU - use whatever you find appropriate .

Panasonics are good enough for First Watt , so I resume that they're good for you too

if possible - put 33mF instead of 22mF ones

re-solder all suspicious solder joints , especially those for NTC - they're visibly old in picture ; clean legs of NTC ( or of any other suspicious part) with razor prior to soldering

 

[Dukja]

ZM:

Thanks for the kind help. I have some more questions:

if possible - put 33mF instead of 22mF ones

Did you mean "replace 220 microFarads with 330 microFarads if possible?" What is the advantage of using 330 or 470 instead of 220 uF?

re-solder all suspicious solder joints , especially those for NTC - they're visibly old in picture ; clean legs of NTC ( or of any other suspicious part) with razor prior to soldering

Is the NTC gray disk looking one? How can you tell the solder joint old (since they are visible from the back side)? Just try to make sure I do the right one.

Also, when people say retouch the solder, do they usually suck out the old one and put on the new solder? or simply reflow the solder? I'll try to retouch as much as possible.

Thanks!!

 

[Zen Mod]

ZM:



Did you mean "replace 220 microFarads with 330 microFarads if possible?" What is the advantage of using 330 or 470 instead of 220 uF?

nope ;

I wrote that for main reservoir caps ;
use 33 instead of 22 ;
mF means miliFarads , so 33mF is 33.000uF ( as microFarads)

ZM:


Is the NTC gray disk looking one? How can you tell the solder joint old (since they are visible from the back side)? Just try to make sure I do the right one.

yes ; darkened area around their legs is telling me that solder joints are cooked with time

......
Also, when people say retouch the solder, do they usually suck out the old one and put on the new solder? or simply reflow the solder? I'll try to retouch as much as possible.

Thanks!!

retouch usually means - just reflow solder joints

I'm saying re-solder , meaning - suck out old solder , clean legs of parts either with razor blade or sandpaper , and solder them back .

if you're not fluent with that work - make as much photos you can , mark positive poles of caps on pcb with red dot etc.
lack of experience can be compensated with patience and care

 

[6L6]

I wrote that for main reservoir caps ;
use 33 instead of 22 ;
mF means miliFarads , so 33mF is 33.000uF ( as microFarads)

I'm going to jump in here and be the 'universal translator' (Like Star Trek!!)

In American electronics terminology, the "33mF is 33.000uF" needs to have the decimal changed to a comma.

Meaning the same thing, Europeans write 33.000uf and Americans write 33,000uf. Both say 33Kuf.

Anyway, the illustrious Zen Mod is suggesting that you replace the 22,000uf filter caps with 33,000uf filter caps. Or bigger, if there is a part that has more capacitance and a similar size.

Here is a link to the Panasonic TS-HA series caps. http://www.panasonic.com/industrial/components/pdf/pic_ts-ha_dne.pdf There is something in there that will work.

Measure your caps with the metric side of your rule. Panasonic cap dimensions are listed in mm. The important dimensions are lead spacing, height and diameter.

 

[Zen Mod]

.....
Meaning the same thing, Europeans write 33.000uf and Americans write 33,000uf. Both say 33Kuf.
.....

meaning that Americans are equally dumb as Europeans , just in opposite direction

so , 6L6 , you're Babelfishing Babelfisherman

 

[6L6]

meaning that Americans are equally dumb as Europeans , just in opposite direction

Well said!!! You understand exactly!