Hi
I recently purchased a X1 preamp from a USA dealer. Full disclaimer I had it shipped to Australia and had the voltage swapped to 240v which is a 5 minute job with the X1s multiple primary transformer. This unit has been recapped by Pass Labs in recent years so I didn't think much could go wrong. Upon plugging it in it instantly started to make a popping sound in the right channel when taken off mute. I haven't listened further as I don't want to hurt my speakers or amplifier, I just moved house and decided to give it another go but the noise remains. Outside of the popping sound it appears to work normally.
Any ideas on the potential issue and maybe some further checks I could do?
I recently purchased a X1 preamp from a USA dealer. Full disclaimer I had it shipped to Australia and had the voltage swapped to 240v which is a 5 minute job with the X1s multiple primary transformer. This unit has been recapped by Pass Labs in recent years so I didn't think much could go wrong. Upon plugging it in it instantly started to make a popping sound in the right channel when taken off mute. I haven't listened further as I don't want to hurt my speakers or amplifier, I just moved house and decided to give it another go but the noise remains. Outside of the popping sound it appears to work normally.
Any ideas on the potential issue and maybe some further checks I could do?
Bizarre.
Is this popping constant ?
Does it pop at a set rate, like once a second, or a variable speed ?
What happens when you change the volume ?
Does the volume of the popping go up and down with the volume ?
Is it just on the rca's or xlr as well ?
Is it just on one input ?
What happens if you disconnect everything but power and output ?
Is it super loud or just a small noise ?
If you can tell us under what conditions it happens, we might be able to narrow down the issue.
If you email the serial number to pass labs, they might be tell you the service history of the unit.
Is this popping constant ?
Does it pop at a set rate, like once a second, or a variable speed ?
What happens when you change the volume ?
Does the volume of the popping go up and down with the volume ?
Is it just on the rca's or xlr as well ?
Is it just on one input ?
What happens if you disconnect everything but power and output ?
Is it super loud or just a small noise ?
If you can tell us under what conditions it happens, we might be able to narrow down the issue.
If you email the serial number to pass labs, they might be tell you the service history of the unit.
Have a look here... a must-read:
https://www.diyaudio.com/community/threads/please-help-me-repair-preamp-pass-labs-x1.257573/
https://www.diyaudio.com/community/threads/please-help-me-repair-preamp-pass-labs-x1.257573/
Ahhhh it turns out Mr Kang and I know each other.
So he has kindly unloaded his X1 onto me for diagnosis and correction 🙂
Once I have a few other things under control, I will investigate its issues.
I shall report here as to what I find and the fix 🙂
Thanks for the link Boky.
So he has kindly unloaded his X1 onto me for diagnosis and correction 🙂
Once I have a few other things under control, I will investigate its issues.
I shall report here as to what I find and the fix 🙂
Thanks for the link Boky.
You can always contact the factory for support on adjustment or parts. If you swap the modules after unplugging for a few minutes that can help narrow it down.
Hi Wayne.
An honour to have you watching this.
I will indeed be contacting PL shortly but wanted to do some preliminary tests first.
Just to keep those watching informed.
After a few quick tests, it way worse than just 'a popping'.
The first minute or two there is considerable static, popping, crackling.
After that, there is always a constant noise. Not loud, but its enough to notice with a small few watt test amp.
Turning the volume up or down results in soft but noticeable clicks.
Interestingly, tapping the top any of the relays (with my finger) elicits a sharp crack. Tapping anything else (boards etc) has no effect.
* I don't believe I'm tapping them hard enough to mechanically move the contacts*
At 'zero' volume, it is of course silent.
It is only the right channel affected.
Volume level and input selection make no difference.
Swapping the ugs and attenuation boards, the fault stays on the right channel.
I have not probed further until i understand how this beastie works. I do Not want to make it worse 🙂
Initial conclusion.
The fault lies in the main board or the front panel board.
At this stage I would suspect an I.C. on the front panel.
Especially as there are 2 ribbon cables that run from next to the att boards to the front panel board.
I am treating the relay tap as a possibly misleading issue caused by ham fists 🙂
Without further knowledge or info, I would throw my money on removing the front board, investigating the I.C's, and swapping out any switching ones.
Now to email PL....
An honour to have you watching this.
I will indeed be contacting PL shortly but wanted to do some preliminary tests first.
Just to keep those watching informed.
After a few quick tests, it way worse than just 'a popping'.
The first minute or two there is considerable static, popping, crackling.
After that, there is always a constant noise. Not loud, but its enough to notice with a small few watt test amp.
Turning the volume up or down results in soft but noticeable clicks.
Interestingly, tapping the top any of the relays (with my finger) elicits a sharp crack. Tapping anything else (boards etc) has no effect.
* I don't believe I'm tapping them hard enough to mechanically move the contacts*
At 'zero' volume, it is of course silent.
It is only the right channel affected.
Volume level and input selection make no difference.
Swapping the ugs and attenuation boards, the fault stays on the right channel.
I have not probed further until i understand how this beastie works. I do Not want to make it worse 🙂
Initial conclusion.
The fault lies in the main board or the front panel board.
At this stage I would suspect an I.C. on the front panel.
Especially as there are 2 ribbon cables that run from next to the att boards to the front panel board.
I am treating the relay tap as a possibly misleading issue caused by ham fists 🙂
Without further knowledge or info, I would throw my money on removing the front board, investigating the I.C's, and swapping out any switching ones.
Now to email PL....
The front panel has four IC's on it. One 87C51 microcontroller that almost never fails and three 74HC573 8 bit latches.
The latches can fail if power is hot swapped. Fortunately the latches are common and cheap.
The latches can fail if power is hot swapped. Fortunately the latches are common and cheap.
I had the same type of problem with a Forte' 3 power amp years ago, the pop was loud and only happened in one channel. FWIW, in that case, it turned out to be a 'worn out' IC at the input. But by the time I was done, it became a project of a much greater scope, since to get to that IC, the amp basically had to come apart. Hope that you find something different.
Ta all.
Yup, the original Fairchild latches are nla.
U2, 4, 5. Fairchild MM74HC573N
I've just ordered some replacement latches.
Best match that is available seems to be this Toshiba TC74HC573APF
https://www.digikey.com.au/en/products/detail/toshiba-semiconductor-and-storage/TC74HC573APF/870519
Oh the're a terrible $1.00 each, oh the pain will robinson, the pain, Ha ha.
I'll be paying more for freight.
I seriously doubt Kang powered it up without the umbilical connected properly.
So if this is the only valid reason for these to fail, then it obviously has to have happened before it left USA.
I have an X1, it's still perfect many years later.
They'll have to pry it out my cold dead hands.
Yup, the original Fairchild latches are nla.
U2, 4, 5. Fairchild MM74HC573N
I've just ordered some replacement latches.
Best match that is available seems to be this Toshiba TC74HC573APF
https://www.digikey.com.au/en/products/detail/toshiba-semiconductor-and-storage/TC74HC573APF/870519
Oh the're a terrible $1.00 each, oh the pain will robinson, the pain, Ha ha.
I'll be paying more for freight.
I seriously doubt Kang powered it up without the umbilical connected properly.
So if this is the only valid reason for these to fail, then it obviously has to have happened before it left USA.
I have an X1, it's still perfect many years later.
They'll have to pry it out my cold dead hands.
They are not that fun to de-solder without proper de-solder tool. And most fun to do it if it solves the problem.
Sometimes CO2 spray can provoke the error?
Sometimes CO2 spray can provoke the error?
Any reason to desolder it as a whole if you have a replacement piece or can you just snip the leads and desolder them one by one?
That would also be my approach but I would like to do it only with a "broken" part 🙂
Holes has to be cleaned for solder etc......easy "on paper"......but sometimes it can "tease you" a bit 🙂
Holes has to be cleaned for solder etc......easy "on paper"......but sometimes it can "tease you" a bit 🙂
I use a solder sucker which is a pain but a reliable way of getting the job done. One of the spring-loaded syringe-looking doohickies. The trick for me is to make sure there is a glob of solder to suck out. If you only have a tiny bit, it is hard to clear the hole. Better off adding more flux and solder.
Also, give it some good heat so it doesn't cool off too much from the time you move your solder gun to the time you suck the solder out.
Also, give it some good heat so it doesn't cool off too much from the time you move your solder gun to the time you suck the solder out.
I also use a solder sucker. I have one which has a soft tip which is made of silicone. It can make an almost airtight connection to the hole. Then it can create some "vacuum". But it has to be done fast after heating (not every time I succeed first time). It seems that 99.9% of solder suckers are with hard PTFE tip today. Difficult to find with silicone tip.
Probably prof. de-solder tools which can heat and suck at the same time exists.
Probably prof. de-solder tools which can heat and suck at the same time exists.
I think I have the PTFE tip. I need to look for one of the silicone-tipped ones then. Good tip 🙂
I have those two type at picture. Left one has the soft silicone tip. Right one has hard PTFE. It is very powerful and almost a bit "violent". A good thing is that the handle you push-in to load it comes back after load so you don't get "knocked out". I remember older types where it stayed in and you could get a hard knock 🙂
I have thought about getting some silicone horse and cut a piece for at spare tip to put on but then I don't get the "toe-in" at the tip but it might work.
If you find a link to the soft-tip types I would like to know 🙂
I have thought about getting some silicone horse and cut a piece for at spare tip to put on but then I don't get the "toe-in" at the tip but it might work.
If you find a link to the soft-tip types I would like to know 🙂
Attachments
Very used to working with i.c's and smd's.
I will protect the board and do a simple leg chop with individual pin removal.
Quick, neat, clean.
Parts are on their way, maybe a week or so to get here.
I'll post again once it's done 🙂
I will protect the board and do a simple leg chop with individual pin removal.
Quick, neat, clean.
Parts are on their way, maybe a week or so to get here.
I'll post again once it's done 🙂
I have a Hakko desoldering gun. You would think that this would be the end all to desoldering. Thing is, if everything isn't perfect, you end up cleaning out the gun as much the time you supposedly save. Solder wick is pretty good, but doesn't cover everything. One more trick up my sleeve is to use cadmium rod to melt with the existing solder. It has a very low melting point, and helps solder spread into the wick. Much of the newer solders from factories are high temp, so I don't know what I would do without it.