A quick resistance check would have readily identified the shorted leg of the HV secondary winding. There is no reason to power up this known smoked and visibly cooked transformer at all. I do not power up a transformer after a resistance check shows a shorted winding when troubleshooting an amp. No reason to, the resistance check reliably verified a shorted winding. Heavy current draw already smoked the thing too, what more evidence do you need? I guess to power it up at full line voltage and switch the test leads around on flying leads....Dangerous instruction here IMO. That said, I appreciate this channel and watch all the vids.
If you notice the tracings do not have any sharp 90 degree angles. Some believe this is best for electron flow. This is in fact true for very high voltage systems but not anything inside of this device and most others.
Thanks for the video. I was looking forward to your part 2 video on this SP10, but I don't see it. Did the customer decide not to proceed due to the cost to repair? If so, that's a shame as this lovely preamp deserves to be fixed. Maybe you could comment here if you won't be making another video on it. As someone mentioned, the transformer can be unwound. Not fun or easy, but it might be worth doing to salvage the rest of the unit (assuming ARC didn't have this part). I bought an SP10 a few years ago and refurbished it. I replaced all the electrolytic caps out of an abundance of caution. A blown cap can take out the power transformer, the hardest part to find a replacement for.
60hrz is a rather low frequency. I think the vibration overtime eats up motors and transformers. Some people have more harmonic distortion in there mains that could help kill it to. Where i live there's three power grids that tie together at times to make power requirements. One station has 6 diesel generators running parallel so you can imagine the dirty power.
I'd take the transformer laminations apart and unwind the secondary until I got to the damaged section. Then just rewind, re-pot and put the core back together. It's not magic; it's sourcing the wire and insulation, attention to detail and patience.
I've never seen such a complicated circuit for a preamplifier.It would be nice if you could walk us through the schematic and explain,for example,how those transistors and op-amp operates in the plate circuits of the tubes.It says on the schematic that they are B+ regulators but I'd like to know how it works.I don't see how the high voltage winding could draw so much current and not blow one of the fuses.There's actually two fuses that could have blown and they didn't.One of them is on the primary of the power transformer and the other is right after the high voltage rectifier so I don't get it.Also I don't see a thermistor anywhere on the power supply could that have helped in saving this very expensive transformer?
Transistors and ICs in the anode feed of the ecc88s in both the phono and line section are series regulators. The silicon transistors form a Darlington Pair. I hope that helps
Hi, I have a Audio research REF 3 preamp, when i switch it on it plays fine, after a few mintues, the left channel fades out and the volume on the right channel goes up and up until i have to switch it off? any idea what it could be?? appreciate any help or advice.. Cheers
A quick resistance check would have readily identified the shorted leg of the HV secondary winding. There is no reason to power up this known smoked and visibly cooked transformer at all. I do not power up a transformer after a resistance check shows a shorted winding when troubleshooting an amp. No reason to, the resistance check reliably verified a shorted winding. Heavy current draw already smoked the thing too, what more evidence do you need? I guess to power it up at full line voltage and switch the test leads around on flying leads....Dangerous instruction here IMO. That said, I appreciate this channel and watch all the vids.
If you notice the tracings do not have any sharp 90 degree angles. Some believe this is best for electron flow. This is in fact true for very high voltage systems but not anything inside of this device and most others.
Thanks for the video. I was looking forward to your part 2 video on this SP10, but I don't see it. Did the customer decide not to proceed due to the cost to repair? If so, that's a shame as this lovely preamp deserves to be fixed. Maybe you could comment here if you won't be making another video on it. As someone mentioned, the transformer can be unwound. Not fun or easy, but it might be worth doing to salvage the rest of the unit (assuming ARC didn't have this part). I bought an SP10 a few years ago and refurbished it. I replaced all the electrolytic caps out of an abundance of caution. A blown cap can take out the power transformer, the hardest part to find a replacement for.
60hrz is a rather low frequency. I think the vibration overtime eats up motors and transformers. Some people have more harmonic distortion in there mains that could help kill it to. Where i live there's three power grids that tie together at times to make power requirements. One station has 6 diesel generators running parallel so you can imagine the dirty power.
I'd take the transformer laminations apart and unwind the secondary until I got to the damaged section. Then just rewind, re-pot and put the core back together. It's not magic; it's sourcing the wire and insulation, attention to detail and patience.
I've never seen such a complicated circuit for a preamplifier.It would be nice if you could walk us through the schematic and explain,for example,how those transistors and op-amp operates in the plate circuits of the tubes.It says on the schematic that they are B+ regulators but I'd like to know how it works.I don't see how the high voltage winding could draw so much current and not blow one of the fuses.There's actually two fuses that could have blown and they didn't.One of them is on the primary of the power transformer and the other is right after the high voltage rectifier so I don't get it.Also I don't see a thermistor anywhere on the power supply could that have helped in saving this very expensive transformer?
Transistors and ICs in the anode feed of the ecc88s in both the phono and line section are series regulators. The silicon transistors form a Darlington Pair. I hope that helps
pls advice where can I buy the transformer ?
Could anybody tell me if this preamp needed for capacitors change (if it was made in the 80s) and how I can get them?
Hi, I have a Audio research REF 3 preamp, when i switch it on it plays fine, after a few mintues, the left channel fades out and the volume on the right channel goes up and up until i have to switch it off? any idea what it could be?? appreciate any help or advice.. Cheers
Check DC voltage supply of tube heaters ....................
Is willing to sell it? Iwould invest to get that unit fixed.
4:44 putting that cap next to those hot tubes, not a very good idea.
Lnk to part 2?
Typical audiofile junk, beautiful looking but poorly designed and no more reliable than any junky Japanese receiver.
Yeah, that's why they are dirt cheap on the used market.
I refused to sell precious nos tubes to an owner of this thing.......