Pray it's not the power transistors.
ARC SD135 will not turn on -- fearing the worst
Yesterday my Audio Research SD135 power amp failed. I turned it on, and the amber protect light quickly turned to green---and then winked out. Then, nothing. Replacing the fuse changes nothing. I have an old ARC D130 that I was able to swap in; it and the rest of my system are working fine.
I sent an email to Audio Research service. Actually, I replied to a previous note from them about the service they were performing on this same amplifier. A few years ago, they replaced a bunch of parts and sent it back, and the amp has seen only light use since then. In his note, Kalvin mentioned problems with the ThermalTrak transistors. I noticed a recent thread that claims these parts are no longer being made. And Kalvin has retired. I hope ARC can do something for me. Any suggestions?
By the way, my power amp is fed by an ARC LS 27, and the speakers are Vandersteen Treo.
I sent an email to Audio Research service. Actually, I replied to a previous note from them about the service they were performing on this same amplifier. A few years ago, they replaced a bunch of parts and sent it back, and the amp has seen only light use since then. In his note, Kalvin mentioned problems with the ThermalTrak transistors. I noticed a recent thread that claims these parts are no longer being made. And Kalvin has retired. I hope ARC can do something for me. Any suggestions?
By the way, my power amp is fed by an ARC LS 27, and the speakers are Vandersteen Treo.
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Here's ARC's response to me: Summary: Since your last repair, the SD135 has made it to the list of products that can no longer be repaired by Audio Research. The same parts Kalvin mentioned below are no longer manufactured and no suitable replacement parts exist. I'm afraid I can only give you the bad news that we will not be able to repair this amplifier for you. We no longer take them in for service. It's a polite response, but it feels like a gut punch. They are leaving me completely in the lurch. They regard this amp, which was a champ 3 days ago, as a piece of scrap metal that I'm going to have to pay to dispose of. I understand the problems with unobtainable parts, but this sure doesn't seem like a way for ARC to retain customers. |
A follow-up from ARC, with some suggestions:
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Here's a thread from two years ago, about another broken SD135. In this poster's case, ARC gave him a credit toward a new amp. The thread discusses the ThermalTrak transistors, which had been discontinued. There's a new version of those parts, but it's not compatible with ARC's design. Apparently, ARC never found a workaround using the new versions of the parts. https://forum.audiogon.com/discussions/my-amp-is-broken-not-sure-what-to-do-any-recommendations/post?highlight=sd135&postid=1637744#1637744 ARC service suggested that used ARC models D240, DS225, DS450 might be of interest. Perhaps a used Ayre power amp might also be a candidate. My preamp is an ARC LS 27, and the speakers are Vandersteen Treo. Thanks! |
I would like to hear from anyone who has replaced the ThermalTrak transistors recently. My tech tells me that replacement parts are entirely compatible with the original amp design: The type # changed slightly, from NJL3281D & NJL1302D to NJL3281DG & NJL1302DG, to signify lead free. This simply means the solder used to "pre-tin" the device pins is no longer lead/tin blend. There was NO other change to device. But I heard a second-hand account from a Mcintosh tech that they had several amps fail because there was indeed a difference between the leaded and non-leaded devices. So is there more to this story than just the part numbers? It would help to have validation from someone who had repaired an SD135 recently. Thanks... |
Regarding ARC's product suggestions to me, has anyone compared the SD135 with its class-D successor, the DS225? I'm not sure about the class-D. But the DS225 has a lot more power supply energy storage going for it, and no overall negative feedback, according to https://www.arcdb.ws/model/DS225 I'm also interested in Nakamichi Stasis amps, although I haven't seen any comments about their use with Vandersteen speakers. |
Hmmm. But the DS225 has a lot more power supply energy storage going for itBut notice that the manual for the DS225 lists "OUTPUT CURRENT: 15 amps peak at protective shutdown." The manual for the SD135: "OUTPUT CURRENT: 60 Amps peak (1 millisecond)" Not what I expected, give the power supply in the DS225. |