X-AS100 upgrade

[eightdigitword]

Currently upgrading both my power amps, thought i'd share the pics, progress and findings.







X-AS100 (x2) Power Amp upgrade plans:
Copper bus bar fitted to phono input/output shared signal L&R
Transformer output is 40v AC + 80v AC to amp, bigger transformer (1KVA 240 x2 40)?
0.22uf MKT 'X2' cap used at mains input on PSU
Re-wire PSU cable to amp cable, thicker cable, twisted pair
Bypass PSU electrolytics with polypropylene type: 0.01uf Vishay MKP1837, LH: C101, C102, RH: C1, C2
Check PSU caps ESR, replace if needed, = 0.03-0.06 ESR from stock PSU caps, surprising from big Jobbycons
PSU electrolytics x4, 6800uf 63v. LH: C101, C102, RH: C1, C2. board can take 50mm dia x 55 tall: Nichicon KG Gold Tune TYPE I 10000uf 63v audio will fit nicely. 31mm height available underside of PCB for more caps if need be, same 50mm dia limit.
MF recommend to bypass (shunt) all audio path electrolytics with high grade polypropylene. Good idea?? - I'm not sure
C3: 10uf 50v NP -ELNA NP
C103: 10uf 50v NP -above
C5: 100uf 16v NP -Nichicon ES type
C105: 100uf 16v NP -above
C9: 1uf 63v - Audio cap, panasonic EB or possible PP film still to check DC on board at this location
C109: 1uf 63v -above
C10: 100uf 63v -Fitted ELNA SILMAC II 63v, going to test with Nichicon KZ also - input de-coupling, signal to earth
C110: 100uf 63v above
C11: 100uf 63v -above
C111: 100uf 63v -above
C19: 220uf 10v -ELNA Cerafine
C119: 220uf 10v -above
Replace BR with Schottky diodes RS: 395-2487 or fast recovery diodes RS: 688-2293 (15ns recovery) 
Clean board with isopropenol
Replace polyester PSU and supply 'bypass?' caps with high grade polystyrene or polypropylene in large capacitance (wima)
C8 - 104J 250v - Replace with 0.1uf 100v Wima
C20, C21, C22 : 104J 250v - Replace with 0.1uf 100v AC Wima
C120, C121, C122 :104J 250v - Replace with 0.1uf 100v AC Wima
Replace polyester plastic film caps at output with polystyrene K71-4: C18: 0.22uf, C118: 0.22uf
Pure copper noise nulling 'belly band' screen fitted to mains transformer, copper tape. soldered and earthed
Replace internal hookup cables with twist pair. 0.7 mm fine silver (99.99% pure) with teflon screen
Twist mains wires and fit a screen using foil tape and heat shrink
Refurbish sockets, check for wear, replace anyway!
Replace ceramic with polystyrenes
C7: 47pf - NOS 47pf 63V POLYSTYRENE FILM & FOIL CAPACITORS - STYROFLEX CAPACITOR KS - heat sink when fitting
C107: 47pf - NOS 47pf 63V POLYSTYRENE FILM & FOIL CAPACITORS - STYROFLEX CAPACITOR KS - heat sink when fitting
Hot glue fix polystyrenes to reduce vibration
Adjust bias to each side
X4 Fuses: F6.3A L 250v removed & polished

slowly working my way through the list, changing bit by bit and listening for a day or so, longer if burn in time is needed. so far sound is improved (i wont go into BS). Surprising improvement came from the copper band fitted round my toroidal transformers in each of my PSU enclosures. I've got 6 sat about a meter away from my hi-fi, i fitted them all with (20mm) copper bands at the same time and was surprised to hear more bass come through than before. This was cheap so i gave it a bash, nothing to loose, probably wouldn't have believe someone if they had told me, bit 'snake oily'. The band must go completely around the toroid and be soldered to to itself, I ran i cable from it (soldered) to the earth pin on my IEC socket. 

[dem0nicf0rces]

Im a proud owner of a secondhand X-AS100 and ever since i bought it the right channel led turned off earlier when i switched it off but it worked just fine.
Inspired by this thread i decided to open up my X-as100 and since i,v recapped the X-10D and a pair of xa 50 s earlier i supposed this wouldn,t be a problem either.
When i opened the unit my attention was drawn to the ,in my unit charred, R 27 4.7 Ohm resistor.
I,m wondering if anyone on this forum would like to help me and could point a probable cause (other than exessive heat) of this burned resistor ?
Also i have some leftover 50 Volt 8200 uF Panasonic capacitors would those qualify to replace the original 6800 uF 63 V  PSU caps ?

[eightdigitword]

old post, i know. posting anyway in case he gets a msg or some other dude is thinking the same thing.

1. sounds like a blown LED, easy to swap.

2. R27 too hot, could look at setting the bias on that side:
www.diyaudio.com/forums/solid-state/303890-sap15-biasing-power-amp.html
otherwise could just be age or something happened to that load, short/speaker melt down, voltage connected across outputs Feck knows

3. 50 Volt capacitors will not do in this location. original is 63v, always fit same or bigger for power cap voltage. Fyi: supply after BR and filter is 55V so you need at least 63v

[chertseyb]

Hi eightdigitword.

I realise that your original post is 6 years old now, but I see that you still have a presence in these hallowed forums, and I owndered if you are able to give your impressions of the work you proposed/carried out in the original post.

Given that my two X-AS100 power amps are now c.20 years old, I feel its time for a DIY ‘update’ (I’ll reserve the word ‘upgrade’ when I can hear the results).

Your outline is really helpful guidance on what to attempt and what parts to consider. In your post you said that many things were still to be tried. Did you come to any conclusons about what was worthwhile?

I’m planning to change all hook up wires, capacitors and diode, but am also wondering about resistors, having seen information (albeit for different amplifiers) claiming improvements in some areas by using e.g. Vishey Mills MRA5.

I am also intrigued by your findings with the band around the toroidal transformer in the PSU. I don’t suppose you have a picture from when you did the work?

Anyway, thank for posting the original details, and I will be grateful for anything you can add on your experience.

[eightdigitword]

ill get pics up on the PSU upgrade. this is where its at in power amps (my conclusion), the transistors usually cannot be upgraded as the entire board is designed for the intended chips and amount of. the output stage is fixed in its design. some fancy caps can improve a little here. I fitted expensive Elna, then tried nicion muse, i preffered the muse, may have been a better day who knows. all the other tweeks are fun but offer little in improvement. In general a good amp should sound of nothing, saying this sounds like that is piffle. no colour should be added. sound in sound out identical only bigger signal.

at 20 years old it is due a re-cap and will benefit hugely from this alone without question. all those caps will have dried out.

on the PSU, big caps are expensive as are toriod TF, the toroid supplied is pretty good (125va per sec, 250va per channel, 500va per TF), the caps are a tad under size due to cost and space. yours are old, so just replacing will be good. or fitting bigger PS caps will help but you too will be stuck like MF was on size. I looked at fitting underneath, above horizontally, mullions of wee ones. in the end the only sensible thing was a separate enclosure. this is a big improvement to the amp, given you need two the cost in the end (£400-500) means a better set of power amps could have been bought (?). I did it anyway and love my amps. go daft, go big fit 50,000 - 100,000uf per channel. Being the dobber i am, i will also buy new torroids for them at some point. this will likely be the biggest improvement to be had (stupidly its the last thing for me to do) i'll be buying these:
airlinktransformers.com/product/chassis-mounting-toroidal-transformer-standard-range-cm0500236
x4 will be rerquired - £200 total

if not making a seperate PS, otehrwise leave the TF as is and just replace the PS caps in the unit.

Some think that the bigger the power transformer, the better, while others maintain that, because audio programme is not continuous, voltage headroom and ample capacitance gives better dynamic performance at reasonable cost. The truth probably lies somewhere in between.

Resistor upgrades....I'm not convinced in this, Japanese hand wound in a vacuum... if you can be arsed it wont do any harm provided you are careful with the board. I fitted fancy ones on the output. sounded the same to me. for the rest of the res, personally i wouldn't bother as there are too many and i cant see how it could improve things. if any looked scorched they should be swapped. the application of the res is whats important, some amps it is more important than others.

changing hook up wires, provided they are thick enough is all you need. at 20 yr s old they will be a bit tatty and oxidized by now. new ones will spruce things up inside! same awg or bigger, dont get $$$$ silly stuff its a waste of money. I mentioned silver..teflon..thats nonsense.

Bridge rec upgrades, I swing between fast diodes are BS and not (in this application). At the moment i have swappable BR boards in my separate PS enclosures. they are standard BR and sound amazing. I intend to make fast diode boards and measure / listen. i'd leave the diodes alone if i was me.

with the copper band round the TF. I copied MF, they offered this in the upgrade service they used to abuse people with. My last property had tons of noise in the mains. the band seemed to help. as did a mains cond i built later on. the same things did nothing at a mates house and at my new house. its cheap and easy so why not. i'll look for pics.

so.....to restore/ tweek a bit:
replace all caps.
leave resistors unless scorched
leave BR diodes (IMO)
fit new wires as they will look nice
clean the board with isopropanol
clean/replace phono connectors
inspect every solder joint and repair if crap
try bypass caps on PS caps

to improve the unit:
consider PSU enclosure with massive cap bank, also consider new TF

[eightdigitword]

s1175.photobucket.com/user/eightdigitword/library/XAS100%20PSU?page=1

[PinkFloyd]

s1175.photobucket.com/user/eightdigitword/slideshow/XAS100%20PSU

[PinkFloyd]

[PinkFloyd]

You can hotlink the photos to the forum eightdigit...... just a couple of examples ^ just copy the IMG code for each image and paste them in when you're making a post here.

For example:



As simple as that mate

All the best,

Mike.

[chertseyb]

Thank you eightdigitword for the reply and additional detail, pics and advice (and thank to Mike for getting the picture links working).

That is an impressive power supply unit.

I am still getting organised for my update. I've ordered capacitors in various flavours (ELNA, Nichicon, Panasonic and WIMA mostly) and will set about replacing the original components and adding by-pass to the big ones. I must admit that I have been seduced by silver internal wiring and will give it a go. Not expecting huge gains but it will look nice.

I've not planned to tackle the outboard PSU in this occasion, but may try the copper band as its a relatively easy thing to do.

Don't know when I can get the work started, but will post pics and results here in due course.

I would not have contemplated doing this without the info and advice here so thanks again to everyone.

[nando]

First: do whatever you like doing.
But I can’t see the necessity to replace wiring. Copper or silver cannot change anything electrons do when they go throught them.

[eightdigitword]

May 1, 2019 14:47:02 GMT chertseyb said:

Thank you eightdigitword for the reply and additional detail, pics and advice (and thank to Mike for getting the picture links working).

That is an impressive power supply unit.

I am still getting organised for my update. I've ordered capacitors in various flavours (ELNA, Nichicon, Panasonic and WIMA mostly) and will set about replacing the original components and adding by-pass to the big ones. I must admit that I have been seduced by silver internal wiring and will give it a go. Not expecting huge gains but it will look nice.

I've not planned to tackle the outboard PSU in this occasion, but may try the copper band as its a relatively easy thing to do.

Don't know when I can get the work started, but will post pics and results here in due course.

I would not have contemplated doing this without the info and advice here so thanks again to everyone.

Splendid.

Post if you have any questions at all.

Take your time, don't rush it.

Take tons of pics/notes to check where stuff was and polarity of caps.

Try to change bits in small groups then listen. Not changing too much at a time. 1. So that you can hear if/any improvements and 2. If it stops working you will know where to look.

Have fun.