The AU-X1 is, like, so hot right now.

Cheers Hyperion - that helps a lot.

Any advice on whether these are referred to in the SM as PC or MC? My understanding is that the blag flags may be polystyrene, is that the case?
 
There is no short cut for this amp, you only get one chance, you will need to dismantle the amp, remove the front, get all those Black Silver Mica capacitors out of that amp. Whilst your in there you might as well just recap it all...
Make a list and go for it, as tempting as it is to fire it up, I wouldn't. I would get your parts ordered and go through it in one go.....
They aren't the easiest of things to pull apart so you only want to be doing it once.

I used Silver Mica caps in place of the black flags, 300-500V range, not the cheapest either, you'll spend about $250NZ on parts, there are a lot of caps in that amp...

Look at whats in the amp, forget the schematic, I never even used it to be honest....

@Ronito6 they use those fusible resistors in that part of the circuit as current protection for the bias circuit. I think perhaps they should have used something a little more heavy duty there, but hard to know how far to let the current run away in the bias circuit before the resistors need to open up.....go too high and you might be in trouble, not enough and the resistors burn up......I suspect they went on the cautious side given the instability of this amp in the early days....but who knows....
 
.....go too high and you might be in trouble, not enough and the resistors burn up......

I used ½ watt metal film replacements for those resistors but put them up off the board on ceramic beads, they have been fine - no signs of trouble.

And agree wholeheartedly your comments regarding SM & Schematic indications of parts - just visually audit your own amp is best. ;)

Silver Mica is a perfectly good choice for replacing the Black Flags which are Polystyrene (according to AK member ConradH's research). However, I used Ceramic C0G/NPO MLCC types with good results. There have been some discussions about the relative merits of either choice, all I can say is that either works well, but 'Ceramic C0G/NPO' is much cheaper. I also like the fact that the ceramics are really tiny, when you are dealing with capacitance as low as 3pf the physical size of the Black Flag (or its replacement) could give rise to 'strays' or unwanted 'pickup' - just my personal view on that last point.
 
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Never been in the X1 however (pinging John) are there any of those annoying green chicklet low value bi-polar caps that give us headaches in the lower x1x series?
-Lee
 
Never been in the X1 however (pinging John) are there any of those annoying green chicklet low value bi-polar caps that give us headaches in the lower x1x series?
-Lee
I don't remember seeing any, capacitors of those values will either be Polystyrene, Polypropylene or Polyester, the last 2 likely being of the red or orange 'chicklet' variety. :)
 
Note well that not all Polystyrenes in the amp are Black Flags.
Yes, noted - I see the traditional polystyrene types in there too.

Thanks for the help peeps.

I think Kevzep is right, I need to don scuba gear this weekend and dive into this bastard to do a black flag full stocktake - yikes......
 
The black flags are in the signal path. You will find them on the cards that populate the 2772 phono motherboard,the the 2775 driver boards, and the flat amp board.

Working on the X1 is a massive task. But why climb mountains...eh?

Thinking about it now, we look forward to basically :
  • a replacement of possibly iffy diodes like the VD1212s or MV03s
  • a replacement of all electrolyics
  • a finding and replacing noisy or just tired transistors
  • a replacing of all relays
  • a cleaning or reconditioning of switches and volume pots
  • RCA jack cleaning or replacement
  • new speaker posts(?)
  • lights replacement
  • and my most hated of all because the solution literally really, really, stinks and is messy ...glue elimination.
Worth it!
 
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2772 phono motherboard,the the 2775 driver boards, and the flat amp board
Thanks Ronito. This helps a lot.

I know it sounds like a lot of work, but I think I will do things in 2 passes here - the first pass, replace all black flags & VD1212's & MV03's, and fuse resistors. Then test the amp. Then upgrade the caps.

How will I know if the small relays are giving me trouble? I have seen posts where people have replaced these.
 
Thanks Ronito. This helps a lot.

I know it sounds like a lot of work, but I think I will do things in 2 passes here - the first pass, replace all black flags & VD1212's & MV03's, and fuse resistors. Then test the amp. Then upgrade the caps.

How will I know if the small relays are giving me trouble? I have seen posts where people have replaced these.

You will hear a low tone / hum suddenly while playing a record. But if you tap or gently press one of the small signal relays with a chopstick or a long trimmer pot adjustment tool, the hum will stop temporarily.

That is how I sussed out the issue. The direct method.
 
Thanks Ronito. This helps a lot.

I know it sounds like a lot of work, but I think I will do things in 2 passes here - the first pass, replace all black flags & VD1212's & MV03's, and fuse resistors. Then test the amp. Then upgrade the caps.

How will I know if the small relays are giving me trouble
? I have seen posts where people have replaced these.

One or the other channel may randomly drop out......I am going to have to do the relays in the X1 I did, they have started to play up...
 
OK - progress report -

I have gone thru and replaced most of the black flags with ceramics and silver micas - I got whatever was in stock for the values I needed.

I have paused at replacing fuse resistors on the F2778 Regulated power supply board. Note that R's 09-12 are stated as being 1/4W 330ohm fusibles in the SM. I checked them all - they seem to be 560ohm, and dont appear to be the usual colour for being fusibles...... Note also that other places where fusibles are meant to be are just wire links (R's 21, 22 & 61, 62).

I'm wondering if these R's 9-12 are even fusibles - the ones I pulled all have the values they are marked at. Should I reinstate these in the PCB or replace with new 1/2watt metal oxide 560ohm 1/2 watt types?

thanks!

IMG_1534.jpg
 
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They don't look like fusibles to me - but now you have them out - you may just as well fit new if you have them on hand

Yep, cool - it will be easier at least doing that, than trying to stuff those stubby leads back into the holes.

So thats interesting, if these arent fusibles, that means of the 8 fusibles that the SM says are in the regulated board, there are actually none. In my board anyway. I certainly cant see any other resistors that look like fusibles in that board.
 
I certainly cant see any other resistors that look like fusibles in that board.
I didn't see any on that board, I did change a few resistors due to 'glue damage' but as far as I can recall, apart from a couple of value changes (described in my thread) to allow correct setting of the PSU voltages that was all I did resistor-wise on the PSU. ;)
 
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OK - I'm done with checking for fusibles - replacing the two on the poweramp module boards, replacing all MV12 and VD1212's with 2 x 1N4148, every single bastard black flag has been pulled and replaced with silver mica or the ceramics Hyperion recommended.

The amp is now back together, apart from extracting the poweramp modules - its actually pretty straightforward pulling this amp apart.....

Re: safe powering up - will a 100W bulb in the DBT work OK? I ask as I had a Pioneer M22 and I suspect that the inrush current circuit in that amp prevented the amp from ever coming out of protection (ie: it needed more current to do so).

This X1 also has an inrush current circuit. Would a 100 or 150W bulb be enough to ensure that (if all is well), the amp will come out protection?

What did others use when testing this amp?
 
Hmmmm, it didnt go terribly......it also didnt go great either.

The only bulb I have is 100W - tried that, its glowing half bright. The relay at the back of the main power supply board clicks in a few seconds later. The powersupply I have then drops from 100V to 70VAC on its meter, so nothing appears to be dragging the voltage right down.

Problem is absolutely no sound. I take it the speaker relays are meant to click depending on speaker selection? Nada there.

The bulb is half glowing bright. I think perhaps there isnt enough current to make the amp work properly? I tried two 60W bulbs in series however Im not sure if that represents a 120W load, or just confirms that I dont really understand electricity that well.......

Tried to set DC offset at speaker terminals however of course, I wouldnt have been getting a proper reading if the speaker relays werent engaged. I also tried to set Bias between the two outside pins pictured. The amount went up and down a bit between say 0 and 13mV, then both sides went down to zero.

I'm going to replace VR 1 and 2 in the power amp boards, then work out where to take the DC offset reading from pre-relay, then try again once the trimmers arrive in a few days.......

Im really not looking forward to having to work on (and take voltage readings) these power amp modules. I havent actually figured out yet how it would be possible to do this - except by running some extended connection leads from the rest of the amplifier to each module? yikes

IMG_1535.jpg
 
Looks like you haven't worked on the Driver modules yet - failure to be able to set bias (or DC offset) is very likely to be 2 x 390 Ohm resistors per driver that are probably fusibles - because they seem to take a beating and go near enough open - mine were up in the ~200K area. :)

These are R36 & R37 (near TR13 & TR14). ;)
 
Can you explain how you have your power supply set up?
I plugged my variac into the DBT which is plugged into 230V, then plugged the 120V transformer into the variac.
This way the load on the 230V light bulb is correct. You do not want the 230V bulb on the 100V supply.
Then I can turn the Variac down to 200V, then the transformer being a 2:1, brings the voltage down to 100V.

70V is too low, its probably not coming out of protection for that reason.

Do you have the front panel on so you can see the power indicator LED, that will flash until the unit comes out of protection.
 
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