Hello all members,
Please allow me to ask for your help. I am a diyer and a member of this forum since may be 7 years.
I recently bought an Ion Obelisk 2.
I changed all the caps. All litle caps are silmcs, including the signal ones. The big 4700μf cap is a Cornell Dubilier(63volts), that was in a drawer. The 10000μf cap was replaced by a 15000μf from kelmet, (40volts), the top of the range. This is a very good cap for me, sounds vintage but without the flaws of most vintage items. Even better than Nichicon KS. For me. The two 2200μf caps in the amp board were replaced by two 1000μF caps from Elna Silmic. I had not 2200μF caps for this position and I thought that 1000μF would be ok.
After this the sound was ok, so I tried to set the bias. I made a short circuit with the legs of one of the transistors. I noticed that the ceramic resistors of the left channel are not the same as in the right channel, so I will change all 4 resistors for new ones. I want to change the transistors but don't know what to buy. Can you please help me here? I will make holes in the heat sinks and remove the clamps, as you Nytecholdie suggested in this thread.
After the short circuit in the left channel, there is no sound, not even in the right channel. Just HUUUUUUUUMMMMMMMMMM...
Thank you very much.
Francisco
Please allow me to ask for your help. I am a diyer and a member of this forum since may be 7 years.
I recently bought an Ion Obelisk 2.
I changed all the caps. All litle caps are silmcs, including the signal ones. The big 4700μf cap is a Cornell Dubilier(63volts), that was in a drawer. The 10000μf cap was replaced by a 15000μf from kelmet, (40volts), the top of the range. This is a very good cap for me, sounds vintage but without the flaws of most vintage items. Even better than Nichicon KS. For me. The two 2200μf caps in the amp board were replaced by two 1000μF caps from Elna Silmic. I had not 2200μF caps for this position and I thought that 1000μF would be ok.
After this the sound was ok, so I tried to set the bias. I made a short circuit with the legs of one of the transistors. I noticed that the ceramic resistors of the left channel are not the same as in the right channel, so I will change all 4 resistors for new ones. I want to change the transistors but don't know what to buy. Can you please help me here? I will make holes in the heat sinks and remove the clamps, as you Nytecholdie suggested in this thread.
After the short circuit in the left channel, there is no sound, not even in the right channel. Just HUUUUUUUUMMMMMMMMMM...
Thank you very much.
Francisco
Would someone accept to repair my Obelisk2? PLEASE!!!!
I live in France.
I called some guys who make repairs, but they use another language, they don't believe in most of the things an audiophile says. I am an alien for them. Sure, they will repair, but I prefer another approach...
I live in France.
I called some guys who make repairs, but they use another language, they don't believe in most of the things an audiophile says. I am an alien for them. Sure, they will repair, but I prefer another approach...
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Ion Obelisk 2 repairs
A few notes to help people trying to get these amps up and running again and to help Francisco below.
the 0.33 ohm metal oxide high power resistors are not so easy to get hold of these days. 5W wirewound types make a good replacement and have little affect on the sound.
No problems with the choices of capacitors except the speaker output capacitors (originally 2200uF / 35v). Fitting 1000uF will significantly alter the bass performance so use 2200uF or you could increase them to 4700uF if you can get some with a small enough diameter as most seem to "short and fat" these days. Element 14/Farnell have suitible 25mm dia capacitors which will fit and should be available in France.
Check all the semiconductors in the affected channel. Because of the lack of LV fusing any faults in the Power amp are usually pretty catostrophically distructive and will take out the output transistors, The protection transistors and the "anti thump" transistors. I would replace all of these in one go and check the three transistors in the input stages and all the diodes as well.
Setting the bias the original "Ion" way needs a really accurate voltmeter as you are only measuring 10mV or so.
The process we use is a bit long winded to go through here so if anyone wants more info then please e-mail us directly at info@nytechaudio.com and we can go through it with you in a lot more detail (which includes how to test the PA section without having another burn up if you dont have a current limiting bench power supply)
A final note about heatsinks which on my earlier post is a little unclear.
The comments about the heatsink and clamps is only really for the original Nytech CA102 obelisk and the first generation Ion Obelisk 1 which had just a thin bent piece of metal for the heatsink and need impruving.
The obelisk 2 and 3 had a far better heatsink arrangement and much stronger clamps so there is no need to alter these and it would be difficult to drill holes through the heatsink anyway as the fins will get in the way.
Hope this helps - Please e-mail us above if you need more information
best wishes and keep safe!
A few notes to help people trying to get these amps up and running again and to help Francisco below.
the 0.33 ohm metal oxide high power resistors are not so easy to get hold of these days. 5W wirewound types make a good replacement and have little affect on the sound.
No problems with the choices of capacitors except the speaker output capacitors (originally 2200uF / 35v). Fitting 1000uF will significantly alter the bass performance so use 2200uF or you could increase them to 4700uF if you can get some with a small enough diameter as most seem to "short and fat" these days. Element 14/Farnell have suitible 25mm dia capacitors which will fit and should be available in France.
Check all the semiconductors in the affected channel. Because of the lack of LV fusing any faults in the Power amp are usually pretty catostrophically distructive and will take out the output transistors, The protection transistors and the "anti thump" transistors. I would replace all of these in one go and check the three transistors in the input stages and all the diodes as well.
Setting the bias the original "Ion" way needs a really accurate voltmeter as you are only measuring 10mV or so.
The process we use is a bit long winded to go through here so if anyone wants more info then please e-mail us directly at info@nytechaudio.com and we can go through it with you in a lot more detail (which includes how to test the PA section without having another burn up if you dont have a current limiting bench power supply)
A final note about heatsinks which on my earlier post is a little unclear.
The comments about the heatsink and clamps is only really for the original Nytech CA102 obelisk and the first generation Ion Obelisk 1 which had just a thin bent piece of metal for the heatsink and need impruving.
The obelisk 2 and 3 had a far better heatsink arrangement and much stronger clamps so there is no need to alter these and it would be difficult to drill holes through the heatsink anyway as the fins will get in the way.
Hope this helps - Please e-mail us above if you need more information
best wishes and keep safe!
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