as you guys are finding out the amp is powerful and sounds good when it works...but there are several design flaws and issues. My unit had failed within three months of owning it. If you shut it off with the volume up at all it blew out the regulator circuit in the power supply. the parts were very close to thier limits in this circuit. when I went to re-design it I found out some of the reasoning behind it. the parts physical size changes greatly to use an appropiate part. I placed large output regulators on the bottom of the unit (T03 package) and the power supply never failed me again. I still have the drawings somewhere for this. the other thing that failed and was a design or poor quality part issue with the tuner. mine quit within the first couple of years.
I still loved my reciever, I did save the pre-amp. I cut down the case and built a new power supply with protection and I use a Phase linear 100w amp. sounds ok but not like the original.
I still loved my reciever, I did save the pre-amp. I cut down the case and built a new power supply with protection and I use a Phase linear 100w amp. sounds ok but not like the original.
EchoWars said:
SA-1000. Unique dual transistor packages, IIRC. Only other place they are available..is in the SA series of power amps, as well. The one's with the huge meters. SA-1000 was 330W/PC@8ohms.
All those pioneers where seemingly purposely built with a 'maximum failure' issue in every unit. What, You say? Well, look at the regulator section for the predrivers and pre rails. Look at the location of the heatsinks and buffer caps. They all fail, eventually. Besides the issues raised here. Other than that, they're great! Love 'em. I want to hug them, and squeeze them... big, shiny, bright, lotsa quality switches, glass panels..and big enough to anchor bodies to the bottom of the lake. What more can you ask for?
No. Go eBay. I'm sure someone is looking.trace59 said:
Me? Had a few out-of-tolerance resistors. Once replaced, bias adjusted fine.anatech said:
Everyone has an opinion. I don't agree with yours or trace59, who believes that all you have to do to kill the receiver is to turn it off. The fact that these units are still running and desirable speaks for itself.
Ancient thread, BTW.
A complementary pair of output transistors consists of both NPN and PNP devices. What I said in my post was that had a bunch of PNP output transistors for the 1980 and 1280, but no NPN's. I think what trace59 is trying to tell you is that he's got both sets of outputs, still attached to the heatsinks, and all are good. If that is the case, and you have a 1980 with blown outputs, you'd be foolish not to jump on the deal.
Trace59,
I authorized it; however, I have no rights in this forum...
Try this one: djwoodworth@shaw.ca
regards.
I authorized it; however, I have no rights in this forum...
Try this one: djwoodworth@shaw.ca
regards.
Be forewarned. The extreme rarity of these devices means that this should NOT be a 'home kitchen-table' fix. Let a competent professional do this...someone you trust. You do not have the luxury of a 'do-over', and if there are blown outputs, there's pretty much certainly a handful of other blown parts on the driver boards.
Hello, I know i am reviving a 10 year old discussion, however I have a similar problem to echowars on his 1980. Mine is an sx 1280 with what it seems the same output transistors and has a blown channel (checked the output transistors and they are dead) .... it seems the MJL4281A and their complementary are up to the task (if not even better since they are rated at 15amp cont.) ... if i simply swap these for the original nec transistors, re-set the bias, etc from the 2 pots .... would it work? or do i need to change some resistors or biasing diodes? If anyone can illuminate me on this mod, i really appreciate. Greetings from Malta(EU)
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