PL400 II Resurrection

TapeHeadOne

TapeHeadOne

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#41
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#41
The original one ? No it came out working, and I just put it back for now. I also need to sort out the wiring to it to make sure I installed it correctly. I took pictures before taking it out, but the colors didn't take particularly well.

Also, be aware that this Mouser part

TO-3.JPG

Is NOT TO-3 as described but TO-220. I'll have to recycle the old ones for now.
 
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mlucitt

mlucitt

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#43
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#43
You can call Mouser and let them know, their customer service is good. They will appreciate the change, they are mostly not electronics types and don't know a TO-3 from a TO-220.
 
TapeHeadOne

TapeHeadOne

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#44
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#44
I already sent them an email and they've opened a case to investigate.

I got shirty and powered it up. It didn't eat it's fuses, but there's 80VDC on the left channel. The right one, with the blown power transistors is fine. I'm guessing a fault in the input board. I wonder if I made a mistake with the wires again. If you guys have a suggestion let me know. I'm waiting for the caps to drain.

Pete
 
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laatsch55

laatsch55

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#45
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#45
A wire problem is possible. Check your predrivers. They'll often go with an output short.
 
TapeHeadOne

TapeHeadOne

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#46
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#46
Thanks laatch yeah, one gone. Last one I took out, I got all optimistic too. Question is, What now ? MJ15003 ? In a pinch I could probably find some BDY56's but I'll throw it in the canal before I pay 20 Eurobucks for a provenance unknown RCA 410

Edit : MJ15022/MJ15024 look viable. The 15003 should be better for gain though, only 140V.
 
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laatsch55

laatsch55

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#49
Full comp, yes you would need the 21196, 21195 complementary pairs.
Quasi comp you would need the 410's as drivers with the 21196 outputs.
Full comp does not require a different transistor in the driver slot.
 
TapeHeadOne

TapeHeadOne

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#52
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#52
Going to be as close as makes no difference to 70 bucks by the time I get it. And if I fuck again ior one of the old ones fails of age it'll be more expensive still.Not happening. Thanks for the suggestion though.
I find it hard to accept there are no 'modern' alternatives for this.
 
laatsch55

laatsch55

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#53
The 410 driver is less prone to causing oscillations than most suggestions.

Perhaps Gepetto will chime in and give us the technical reasons just what modern replacement is not desirable.
If you do try something different you would need a scope to check for oscillations. Those darn silent amp killers.
 
laatsch55

laatsch55

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#54
There is not much demand on the driver as opposed to the outputs. An old, tested 410 doesnt bother me in the least.
 
TapeHeadOne

TapeHeadOne

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#55
If I could buy 10 or so at once I would consider it, if from a European registered VAT business it's not an issue at all. But 20 bucks a piece ? Sorry Dave, I can't do that.
 
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