johnsonwu, cool!
My Amp is Broken - Not Sure What to Do - Any Recommendations?
I went to turn on my Audio Research SD135 amplifier the other day, but it will not turn on. According to the Audio Research service technician I spoke to, the problem is a broken Thermal Trak module chip. He said that it is a temperature sensing component, and that replacements are no longer being manufactured. He said that it is a known problem, and that Audio Research will give me credit to purchase an Audio Research amplifier from an Audio Research authorized dealer.
I was wondering if Audio Research makes anything powerful enough to drive Vandersteen 3A Signature speakers (which need between 100 - 200 watts of power)? I am using an Audio Research SP8 Mk II as a pre-amp.
I don't really have much of a budget and am not sure what to do. I would appreciate any advice. Thank you.
I was wondering if Audio Research makes anything powerful enough to drive Vandersteen 3A Signature speakers (which need between 100 - 200 watts of power)? I am using an Audio Research SP8 Mk II as a pre-amp.
I don't really have much of a budget and am not sure what to do. I would appreciate any advice. Thank you.
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- 57 posts total
Hey all, Thank you for the replies and helpful advice. The fellow I spoke with at Audio Research told me the Thermal Trak transistors currently offered by OnSemi are a new version of the ones used in my SD135. He said that unfortunately they are not the same as what was used in the SD135 and (according to him) will not work in my unit. The guy I spoke with at ARC told me that the company considered trying to come up with a work around for the original Thermal Trak transistors no longer being available, but nothing ever materialized. I suspect a lot of people are going to be having difficulty with their amps over the next decade or so when the Thermal Trak transistors fail on them. These particular parts are known to have a somewhat significant rate of failure. Besides Audio Research, McIntosh used them, as well as Arcam, Mark Levinson and Ayre. https://www.diyaudio.com/forums/solid-state/237929-thermaltrak-transistors-discontinued.html I believe some manufacturers are still using the latest versions of Thermal Trak transistors in their current product lines. Although it looks like Ayre just stopped using them this year: https://www.audioasylum.com/cgi/vt.mpl?f=amp&m=184484 Anyway, this really stinks. I never would have thought this would have happened when I purchased my SD135. I may be wrong, but I think if Bill Johnson were still alive, ARC would come up with the work around to service the discontinued gear of his loyal customers. |
https://www.mouser.com/ProductDetail/ON-Semiconductor/NJL3281DG?qs=sGAEpiMZZMvFp%252byPHbnZYyVkaBWrH... 3281D was INDEED obsolete. Original collateral dated June 2006 http://www.onsemi.com/pub/Collateral/NJL3281D-D.PDF replaced by 3281DG Same application notes per Mouser.com and ONSemi. Available and NOT discontinued. My HD220 has not blown (yet) so I have not attempted a repair myself. I suspect it means you need to change out ALL the devices for matching sake. That's likely why Audio Research doesnt want to deal with it. Boy if they could just respond to my email and get me the schematic! |
OP lucky you the schematic is HERE: https://elektrotanya.com/PREVIEWS/63463243/23432455/audio-research/audio-research_sd135_amplifier_sc... I bet not everything is toast likely 1 phase of 1 channel. Get a tech WHO KNOWS HOW TO MATCH OUTPUT DEVICES. Buy a dozen of NJL3281DG (NPN) NJL1302DG (PNP) and match them and repair the blown channel! |
- 57 posts total