I bought it to drive these beauties….
That sounds fair. Circle back here with some listening impressions when you get the amp sorted out 🙂
Another thought, if you contacted Jon Soderberg by email and sent him photo's of the board, he would be able to reply as to whether the board is indeed repairable and some indicative costs. The way air mail costs are going these days, sending boards there and back would most likely cover the cost of new FE boards, let alone the actual repair costs.
Lovely looking speakers by the way, hope they sound as good as they look.
Lovely looking speakers by the way, hope they sound as good as they look.
Yes, someone has made a bit of a mess with them previously, good luck with however you proceed and keep us updated as Mike mentioned.
I would also try and clean the rest of the amp while apart.
I would also try and clean the rest of the amp while apart.
Just tested the large 15000uf power supply caps and 2 are just over 15k and 2 are 13k , should I be concerned?
-So my old threshold had a few point-to-point things going on as well on the original front end. I think as Threshold made changes to the schematics, they would just wire them up on the PCB boards.
-The device in the picture where the left leg was not attached is probably a BJT transistor.
-How are you testing the caps?
-The new stasis front ends can be printed at JLCPCB.com. The shipping is what generally bites you but it is inexpensive nonetheless. I am trying to remember what amplifier Pass designed the boards for. It may have been a stasis 2 or stasis three so the mounting holes may line up with yours. If not, you will either have to drill holes where there are no traces or make a little bracket to accommodate the new front end. I had to make a bracket myself.
-Get some isopropyl alcohol and an old tooth brush. Start gently scrubbing the board to clean all of the old soot and flux. That should help things to make sense a bit more.
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Your speakers look great! What the heck are those things??!! 🙂
-The device in the picture where the left leg was not attached is probably a BJT transistor.
-How are you testing the caps?
-The new stasis front ends can be printed at JLCPCB.com. The shipping is what generally bites you but it is inexpensive nonetheless. I am trying to remember what amplifier Pass designed the boards for. It may have been a stasis 2 or stasis three so the mounting holes may line up with yours. If not, you will either have to drill holes where there are no traces or make a little bracket to accommodate the new front end. I had to make a bracket myself.
-Get some isopropyl alcohol and an old tooth brush. Start gently scrubbing the board to clean all of the old soot and flux. That should help things to make sense a bit more.
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Your speakers look great! What the heck are those things??!! 🙂
Hi Mike .
I am so determined to get this thing running again but sadly I don’t think I have the knowledge needed to do so unless I get lucky with these boards and they actually work but even then I’ll have to invest in a variac I suspect.
I’m kind of hoping that the 2 lose wires and the unsoldered leg of that BJT transistor caused the original failure, now I’m not sure about the story about it being brought to life with a variac and then used for a week is true given the lose wires .
The speakers are Troels Gravesen Ekta 2’s .
Andy
I am so determined to get this thing running again but sadly I don’t think I have the knowledge needed to do so unless I get lucky with these boards and they actually work but even then I’ll have to invest in a variac I suspect.
I’m kind of hoping that the 2 lose wires and the unsoldered leg of that BJT transistor caused the original failure, now I’m not sure about the story about it being brought to life with a variac and then used for a week is true given the lose wires .
The speakers are Troels Gravesen Ekta 2’s .
Andy
Here is one of the amps that Pass designed the new front end for. You are in luck. It happens to be a Stasis II.
https://www.diyaudio.com/community/threads/new-stasis-front-end.363701/post-6442814
On your bad board, I suspect the issue lies in the active devices to the right of the burnt resistor. It would be good to see where the burnt resistor is in the schematic and go from there. It looks like something similar happened to the other channel and the actives were replaced.
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Those speakers are spectacular! Whoever build those did a wonderful job. What have you been powering them with up until now?
https://www.diyaudio.com/community/threads/new-stasis-front-end.363701/post-6442814
On your bad board, I suspect the issue lies in the active devices to the right of the burnt resistor. It would be good to see where the burnt resistor is in the schematic and go from there. It looks like something similar happened to the other channel and the actives were replaced.
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Those speakers are spectacular! Whoever build those did a wonderful job. What have you been powering them with up until now?
Thanks again Mike ( what are the Active devices? )
Let me take you back a few weeks in the life of Andy the tired of box swapping Hifi obsessed maintenance man 😁
I WAS very happily running exposure mono 8’s with a 21 pre into my Ruark Crusader 2’s , I remember at Christmas thinking how wonderful it sounds and “ that’s it I’m done swapping “ ( yeah right ! ) and then these TG speakers showed up for sale ( I had to have them right ) somehow I managed to get the money together to buy them not realising that the exposures just weren’t up to job of driving them properly , so the next quest was to buy something that would drive them ( though buying the speakers has left me broke ) and then the stasis popped up ( as faulty) and this was my opportunity to obtain a beast to drive the speakers.
I’m currently using some HD Audio monoblocks ( made in UK ) and my Counterpoint SA-2000 . I have autism which doesn’t help when obsessed with having great sounding gear and knowing that it’s under par ( in fact I barely use it now ) this is why I’m so keen and anxious to get the Stasis running.
Below are my HD Audio pre and monoblocks, very rare as only 24 were ever made before the maker folded due to a divorce.
Let me take you back a few weeks in the life of Andy the tired of box swapping Hifi obsessed maintenance man 😁
I WAS very happily running exposure mono 8’s with a 21 pre into my Ruark Crusader 2’s , I remember at Christmas thinking how wonderful it sounds and “ that’s it I’m done swapping “ ( yeah right ! ) and then these TG speakers showed up for sale ( I had to have them right ) somehow I managed to get the money together to buy them not realising that the exposures just weren’t up to job of driving them properly , so the next quest was to buy something that would drive them ( though buying the speakers has left me broke ) and then the stasis popped up ( as faulty) and this was my opportunity to obtain a beast to drive the speakers.
I’m currently using some HD Audio monoblocks ( made in UK ) and my Counterpoint SA-2000 . I have autism which doesn’t help when obsessed with having great sounding gear and knowing that it’s under par ( in fact I barely use it now ) this is why I’m so keen and anxious to get the Stasis running.
Below are my HD Audio pre and monoblocks, very rare as only 24 were ever made before the maker folded due to a divorce.
Here’s a link to the step by step build of my speakers…
https://audioaddictsforum.com/thread/2466/floorstander-build-striving-high-end?page=2
https://audioaddictsforum.com/thread/2466/floorstander-build-striving-high-end?page=2
So what’s the worst that could happen should I replace the damaged resistors, replace the capacitors , re solder the boards back in place and power it up ?
An active device is something like a transistor, or a diode. A passive device is something like a capacitor or resistor. So the active devices that I was referring to were the transistors. It looks like on the left board, at least four of the transistors were replaced.
I think if you are going to do some part swapping, index the old parts that you are swapping on the schematic with labels and put them into a baggie.
Typically you would go through and check the parts as you are pulling them to try to figure out where the fault is. IE, follow the resistor that is blown, what it's job is in the circuit and test the component down the chain that would cause it to pull so much current.
But I know this is beyond your skillset at the moment and you are trying to sort this out inexpensively.
Wow, the work that went into those speakers. You should be proud to have them. 🙂 I bet they are going to sound great!!
Hard to say. I would think the resistor would blow again... If you do this, it may be a good idea to lift the resistor off of the board a bit. So the heat/soot etc doesn't go into the board. You also risk blowing the traces like on the left channel board.
I think if you are going to do some part swapping, index the old parts that you are swapping on the schematic with labels and put them into a baggie.
Typically you would go through and check the parts as you are pulling them to try to figure out where the fault is. IE, follow the resistor that is blown, what it's job is in the circuit and test the component down the chain that would cause it to pull so much current.
But I know this is beyond your skillset at the moment and you are trying to sort this out inexpensively.
I think I might as well replace all the transistors then whilst the boards are out .
Would there be any harm in replacing the wires ( they’re short and thin) for slightly thicker and longer ones , this will make installation and removal of the boards far easier.
Would there be any harm in replacing the wires ( they’re short and thin) for slightly thicker and longer ones , this will make installation and removal of the boards far easier.
After looking at those speakers, I now know how you got your name - beautiful work.
With regards to the Stasis 2 repairs. If you are going to try a repair on the boards, I would change transistors on both channels - carefully along with other blown or dubious looking components, so that both channels were the same. You will need to source the correct parts. I would still send Jon an email showing him the state of the boards ( he might be able to send you original transistors for instance)
I would replace the wires with very flexible multi stranded silicon insulated wire.
Looking closely at the photo's of the boards, there is a lot of damage and previously replaced transistors from what I see, hopefully these were replaced with original or equivalent types.
If it were me, and you had the experience, I would be replacing the old damaged FE boards with the newly designed NP FE boards. There are 2 versions of that board in the Stasis FE thread - the NP one as shown in post #1 and a Zen Mod designed pcb later on in the thread that is physically a lot smaller, but with a more dense component spacing. To get these done , as Mike has said you would need to order the boards using the gerbers in the thread at JLCPCB, then source the new components and build them up. Maybe there is someone in the UK that has spare boards that can help you - I would be surprised if there wasn't as a lot of Threshold amps ended up in the UK back in those days. Maybe have a read through the complete Stasis FE thread and see who has posted there from the UK and contact them by PM.
While you have the amp apart, check the output stage on each channel (compare between the 2) for the emitter resistors and the OP transistors with a DMM.
I would also look at changing out the old PSU caps for new ones of the same diameter and height as long as they have the same or higher voltage rating and the same capacitance value or higher - you should be able to find ones with a higher capacitance for the same can size.
It is definitely worth spending the money and getting the amp up and running again.
With regards to the Stasis 2 repairs. If you are going to try a repair on the boards, I would change transistors on both channels - carefully along with other blown or dubious looking components, so that both channels were the same. You will need to source the correct parts. I would still send Jon an email showing him the state of the boards ( he might be able to send you original transistors for instance)
I would replace the wires with very flexible multi stranded silicon insulated wire.
Looking closely at the photo's of the boards, there is a lot of damage and previously replaced transistors from what I see, hopefully these were replaced with original or equivalent types.
If it were me, and you had the experience, I would be replacing the old damaged FE boards with the newly designed NP FE boards. There are 2 versions of that board in the Stasis FE thread - the NP one as shown in post #1 and a Zen Mod designed pcb later on in the thread that is physically a lot smaller, but with a more dense component spacing. To get these done , as Mike has said you would need to order the boards using the gerbers in the thread at JLCPCB, then source the new components and build them up. Maybe there is someone in the UK that has spare boards that can help you - I would be surprised if there wasn't as a lot of Threshold amps ended up in the UK back in those days. Maybe have a read through the complete Stasis FE thread and see who has posted there from the UK and contact them by PM.
While you have the amp apart, check the output stage on each channel (compare between the 2) for the emitter resistors and the OP transistors with a DMM.
I would also look at changing out the old PSU caps for new ones of the same diameter and height as long as they have the same or higher voltage rating and the same capacitance value or higher - you should be able to find ones with a higher capacitance for the same can size.
It is definitely worth spending the money and getting the amp up and running again.
Thanks mate , I have emailed Jon but no reply as yet.
I’ve already tried to source the transistors and found some ( or equivalents ) from a supplier in London but they nor any other suppliers have the others ( Motorola mps 6561 ebc) ,( 018mps a42 ) or Fpn 4250 ebc .
I’ve already tried to source the transistors and found some ( or equivalents ) from a supplier in London but they nor any other suppliers have the others ( Motorola mps 6561 ebc) ,( 018mps a42 ) or Fpn 4250 ebc .
I would also pull the whole amp apart ( document every connection with drawings / photos ) and clean the output boards up getting rid of all that old solder flux, all the dust out of the chassis etc. That will make it easy to completely check each output board, fit new caps and check every wire connection - reflow all joints.
Hopefully Jon can help out with new transistors, he can be slow in replying if busy from what I have heard..
Hopefully Jon can help out with new transistors, he can be slow in replying if busy from what I have heard..
Finding the original active devices will be tricky and your existing PCBs have a fair bit of damage to them.
I would consider building the revised front end on new PCBs. I just checked and it's pretty inexpensive getting the boards made at jlcpcb.com and the parts (or functional equivalents) are more or less available.
Good luck with your repair.
I would consider building the revised front end on new PCBs. I just checked and it's pretty inexpensive getting the boards made at jlcpcb.com and the parts (or functional equivalents) are more or less available.
Good luck with your repair.