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Pioneer SX-1980 Transistor Modification

Interesting to see this thread still kind of going.
I wonder, what would be wrong with using 2SA1494/C3858?
 
tarior said:
Interesting to see this thread still kind of going.
I wonder, what would be wrong with using 2SA1494/C3858?
Click to expand...
An MT-200 with appropriate specs would be fine. If you're talking about using without any mods, the only problem is that MT-200 mounting hole spacing is about 6mm off
 
I don't have one in front of me, so I was just wondering. Not gonna get out of either drilling holes or making custom hold downs either way. What actually brought it up was tracking down info for a MCS 3125 that I'm tinkering on. They use the same output transistors that the Pioneer SX-xx80 series use.
 
I have enough original devices to redo one 1980. (If they work, which I'm not certain that they do, but were sold as NOS.) With any luck, I'll never need them. But I'm keeping a close eye on this thread. If I didn't do it before, I'd like to say thanks and "God Bless You" to Echowars.
 
If the outputs need replacing, I would be using MJL4302/4281 in a 1980. They are 230W devices. I see MT-200 is discontinued and MJL1302/3281 are back ordered til Nov, they are saying, someone is still using lots of these devices, they are emptying the shelves.
 
Doing a search for the 6 output trans isolation pads using the new style transistors, of course the originals were a mica type..I could get mica but I really want to stick to what echo used.... echowars mentioned ( in his sx 1980 trans mod thread) he used the Bergquist pads but no details on the part# etc..there are many choices out there.and most do not give the size specs or much detail on them..kinda in the dark about these.. also considering getting the new AWR-154 listed on ebay..(450.00+!!) my original works but could use some mods..anybody using that new one?..any help would be great! Thanx!!
 
fulton said:
Doing a search for the 6 output trans isolation pads using the new style transistors, of course the originals were a mica type..I could get mica but I really want to stick to what echo used.... echowars mentioned ( in his sx 1980 trans mod thread) he used the Bergquist pads but no details on the part# etc..there are many choices out there.and most do not give the size specs or much detail on them..kinda in the dark about these.. also considering getting the new AWR-154 listed on ebay..(450.00+!!) my original works but could use some mods..anybody using that new one?..any help would be great! Thanx!!
Click to expand...
Tony just did a video on this mod (why buy a populated board when you can buy an unpopulated board and the parts for less):
 
Too bad this thread did not get moved into the Pioneer forum, you could ask mods to move it since you would probably attract more responses
I have never done this mod but the wiring seems straight forward. Compare the pinouts of the original device to the replacement swap 1:1. The old package had 4-leads, both outside ones being the same, iirc it was the collectors but I would have to check to be sure
Search the pioneer thread it might have the info/pics you are looking for
 
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Thanks. I haven't really taken a close look at the existing wiring yet but the 4 leads down to 3 leads had me wondering if it was complicated.

Also is there anyone at AK producing the hold-down plates? I'd rather pay someone at AK rather than a local machine shop.
 
I was under the impression that everyone hand fabricated their metal as it is pretty simple to do with a few hand tools. The cost to get them made up maybe uneconomical and in small demand
 
tarior said:
I don't have one in front of me, so I was just wondering. Not gonna get out of either drilling holes or making custom hold downs either way. What actually brought it up was tracking down info for a MCS 3125 that I'm tinkering on. They use the same output transistors that the Pioneer SX-xx80 series use.
Click to expand...

Just curious if you ever got anywhere with swapping outputs on the 3125? One of the 2SD746s in mine died.
 
@dapbmw

hoppesbrain.com

2SD746 / 2SB706 to TO-3P / TO-247 Transistor Heat-Spreaders / Adapters

2SD746 / 2SB706 to TO-3P / TO-247 Transistor Adapters / Heat-Spreaders
hoppesbrain.com hoppesbrain.com
(No affiliation.)

I made a similar hold down for MT-200 transistors. If you know the size of the plates he used, it might be the same. What is the hole spacing and how many do you need?

EDIT: I've read the entire thread and the Pioneer transistors are larger than MT-200. It would not be difficult to fabricate some out of aluminum. I made mine out of .090"aluminum and I think much thinner would have been fine.
 
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redk9258 said:
@dapbmw

hoppesbrain.com

2SD746 / 2SB706 to TO-3P / TO-247 Transistor Heat-Spreaders / Adapters

2SD746 / 2SB706 to TO-3P / TO-247 Transistor Adapters / Heat-Spreaders
hoppesbrain.com hoppesbrain.com
(No affiliation.)

I made a similar hold down for MT-200 transistors. If you know the size of the plates he used, it might be the same. What is the hole spacing and how many do you need?

EDIT: I've read the entire thread and the Pioneer transistors are larger than MT-200. It would not be difficult to fabricate some out of aluminum. I made mine out of .090"aluminum and I think much thinner would have been fine.
Click to expand...
Yes indeed one can make their own spreader/adapter plate. I get aluminum scraps free at windows factory. which are .5 or thicker. For the price of Hoppe Brain plate @$20 for a set I'll make 4 for free. I tend to buy made ones before but with economic situation and price of metals going up, I'd stick with the free scraps. You can buy a sheet of Silpad and cut your own MT-200 pads and still come out ahead.
 
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