Repairing broken X-Can V2

[tomco]

Hi Guys,

I picked up a modded X-Can V2 for €150 a few days ago on another forum. It worked fine for about a day, then one morning I woke up and the power was gone in the whole house.

After resetting the breaker I noticed the X-Can wasn't working. I replaced the PSU with a random 12V 1.5A unit I found in a drawer. Thankfully the LED lit up and I figured everything was fine, however I could only hear sound from the amp at the highest volume level (and even then it was whisper).

I took it apart and discovered the amp had been modded much more than I was told (supposed to be only the tubes), but by someone who clearly had never touched a soldering iron before!

Seriously, its a mess in there:

imageshack.us/g/96/imag0448jy.jpg/


Anyway, after reassembling I'm not even getting a whisper of sound. Still getting the lit LED though. Is it possible my PSU is insufficient?

Any tips or links on how to go about diagnosing the issue?

[elysion]

Send a PM to Mike (PinkFloyd) if the doesn't see your post within the next 1-2 days. He's the ultimate expert for X-Can's. I know no one that has more experience with these amps.

I've had a look at your pics. I see no blown caps, but I've noticed that there are no Jamicon caps inside (MF has sold the X-Can's with crappy Jamicon caps rated at 85 degrees C orginally). It looks like the amps was already modded.

Did you check that your PSU is really one for AC? DC would kill components inside the amp. Sorry for the stupid question, but that's a mistake that is quite common.

[tomco]

Thanks, nope its definitely an AC adapter from an external hard-drive.

Input: 100-240V, 50-60Hz, 0.5A max
Output: 12V, 1.5A
LPS

[Deleted]

Jun 4, 2012 1:17:05 GMT tomco said:

Thanks, nope its definitely an AC adapter from an external hard-drive.

Input: 100-240V, 50-60Hz, 0.5A max
Output: 12V, 1.5A
LPS

External adapters for HDDs are normally +12V DC and +5V DC, NOT A.C.

Alex

[XTRProf]

X-Can V2 needs a 12 VAC input and NOT a VDC 12V.

[XTRProf]

After looking at the pictures, I saw good Panasonic FC caps in it. So you are still good. Those brownish "tans" on the PCB is because of the overheating caused by the power transistors and tubes heat. This is due to the V2 NOT ventilated as well as the cheap poor PCB used and high usage by the original owner.

Check out my X-Can V2 thread for what I mean.

[Deleted]

Jun 4, 2012 1:17:05 GMT tomco said:

Thanks, nope its definitely an AC adapter from an external hard-drive.

Input: 100-240V, 50-60Hz, 0.5A max
Output: 12V, 1.5A
LPS

This is definitely a DC adapter.
It will switch on the LED on the amp and only the positive half of the amp will be 'working' and will have a too low voltage as well.

The adapter won't be weighing much either.
a 12V 1.5A AC transformer is relatively heavy in weight.

100-240V shows it is a wide range power supply.
They do ONLY exist for DC power supplies.
It just says 'AC adapter' on the label because it is connected to the mains which is AC.

I know of no HD's that have an AC 12V inlet.
As Alex has said they are usually 12V DC and the smaller ones 5V DC

Get yourself a 12V transformer.

It's highly likely the amp is still O.K. and only the ttrafo is defective.
I wouldn't mess with the amp untill you tried a proper AC power supply/trafo

[mrarroyo]

OP if you are in the USA you can pick a cheap correct power supply at: www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=167151

[Crispy]

Send a PM to Mike (PinkFloyd) if the doesn't see your post within the next 1-2 days. He's the ultimate expert for X-Can's. I know no one that has more experience with these amps.I've had a look at your pics. I see no blown caps, but I've noticed that there are no Jamicon caps inside (MF has sold the X-Can's with crappy Jamicon caps rated at 85 degrees C orginally). It looks like the amps was already modded.

Mike is your man to get your amp up and running again - he's the best.

I have also had a look at your photo's and I thought my soldering was bad

I do not have any electrical experience other than upgrading my XCan V2 - but looking at the soldering around the transistors this may well be where your problem lies??

[XTRProf]

Yeah, I agreed with Chris after relooking at the pictures. Redo those poor soldering even if they are not the problem as they may cause problem later as the PCBA copper trace is pretty bad and will lift with heat just like mine.

[tomco]

Thanks guys!
I'll try to get a replacement psu on ebay and then resolder anything dodgy, some of the traces are in bad condition so I might jump them.

Any idea what mods were done, anything left for me to add?
I know the caps have been changed, but it looks like the op amps have been swapped too.

[mrarroyo]

The V2 did not have op-amps only the V1.

[tomco]

Oops, sorry I had a few drinks on me.
MOSFET's not opamps!

[XTRProf]

Jun 5, 2012 12:20:10 GMT tomco said:

Oops, sorry I had a few drinks on me.
MOSFET's not opamps!

Really over drank? Not MOSFET but DARLINGTON transistors, darling .................... Tube/Transistor hybrid HA and not Tube/Mosfet HA as are the current hot favourite threads here in RG.

[tomco]

Well there you go, learn something new everyday.
I really must go over the schematic.

(is there such a thing as over drinking?)

[PinkFloyd]

Best thing to do with the transistors is to desolder the "blobs" and then scrape back the green coating on the tracks (with a sharp craft knife) to expose the bare copper underneath.... reflow with fresh solder and this will supplement the joint (flow onto the exposed copper) you could also get new transistiors and form the legs so they substitute the track (again, scraping back the track to the bare copper) and point to point them whilst also soldering them onto the good parts of exposed copper track.

The tracks are very weak and the heat from the transistors causes them to fall apart... this is quite common but the fix is easy.

Mike.

[tomco]

Thanks guys, I've sorted it now.

Picked up one of these tinyurl.com/cpczpf3 and resoldered the transistor like so:



Not the neatest job in the world (looking at the pic now I should probably have reinforced the middle pin better) but I had the idea of using some saturated desoldering braid to bridge the lifted traces which I think worked very well.

Cleaned up the rest of the board too, in all I sucked about a marble sized ball of excess solder off the PCB.

[XTRProf]

Great! So HA working now? Btw, use some deflux solvent or alcohol with a tooth brush to clean up the soldered area to make it look more like a professional jobby.

[tomco]

Yep, all working. Sounds great.
Thanks for tip, I'll clean up the board when I get around to changing the volume pot.