Ron's Carv M1.5T Recap

[jbeckva]

Got this from Ron/Northwinds. Need to put in the special cap assy pictured in the 2nd pic - The stock ones are actually two caps in a single package, so twice the number of pins on the bottom.

Supposed to be a drop in replacement, but it's the "journey" getting it torn down to get at 'em that's going to be the story... heheh (thank gawds for power tools! )

 

[jbeckva]

Oh hey Ron! Man awesome surprise in the mail today. Jamming on some Eagles at the moment while working on the amp. Thanks Bro.. appreciate it big time!

Yeah.. might as well get the rest of those components. I only want to crack this nut once, hah!

 

[eminence1963]

Holy cow thats a lot of transistors. I wonder if my 1.0 has that many as well?

 

[Northwinds]

Oh hey Ron! Man awesome surprise in the mail today. Jamming on some Eagles at the moment while working on the amp. Thanks Bro.. appreciate it big time!

Yeah.. might as well get the rest of those components. I only want to crack this nut once, hah!

It's the least that I can do Jer, you have looked out for me a lot and I hope that selection of lps will be enjoyable for you!

Man, that looks like a shitstorm!!!!!! One of those silver thingies is bad also? Let me know what you feel it needs. I am also wondering what to do for feet for that beast, that silicone ain't gonna fly

Before I sent it to you, I put the gas to her and she sounded ok except for that stinking subdued hum heard when no source was playing. I sold the M200 for $50, someone else will appreciate it more and can have fun fixing it. I still need to get the C1 done also at somepoint, I plan to use it with this M1.5T eventually

 

[laatsch55]

I have a link to an outfit that makes "feet" for anything, just gotta find it. Jer I also have a lot of feet from stuff I've scrapped. Let me know.

 

[laatsch55]

MJ15003's and 15004's???

 

[jbeckva]

MJ15003's and 15004's???

Yep, and some 024's... 025's... weird mix of 'em

 

[Northwinds]

Yep, and some 024's... 025's... weird mix of 'em

Uh oh, that sounds bad. The amp was owned by Kimber Kable so perhaps they just put whatever they had on hand to keep it running. This was one of their test mules I am assuming to showcase their products

 

[jbeckva]

Yeah we might want to "Call a Joe" in on this one, hehe... I have the SM, and at least from one of the revisions we basically see that

1. There are 10 total TO3 cans per channel

2. 8 of which SM says MJ15024's for the top half and MJ15025's for the bottom. But .. 2 (per rail, per channel) are in one configuration like cascode, etc, while the other two are configured differently

3. The remaining two appear to be some sort of main power voltage "pass through" or switching Q's.. SM calls for MJ410 on the top/pos half and MJ6502 for the bottom.

So THAT is what the SM calls for.. but in reality...

Q3 and Q8 (the 6502 and 410) are really MJ15025 for Q3/6502 and MJ15024 for Q8/MJ410

Q1 and Q2 (should be MJ15025's, makes up the 2 Q "cascode")... are really MJ15004's

Q4 is an 024, Q5 is an 004

Q6 is an 024, and Q7, Q9, and Q10 all 003's

Q9 and Q10 are the 2 that make up the 2 Q "cascode" on the positive half., leaving Q6 as an 024, Q5 as an 004

All sorts of funky Q arranging going on. Joe if I send a skeezer your way... ???

 

[Northwinds]

Man, when they say these amps are built like no others they mean it! I remember reading a post from someone saying the way these are built, nothing is setup like you expect in other amps

 

[laatsch55]

Jer I have a troubleshooting guide for the magnetic field amps. There are certain things that have to be done in a certain order, or nothing gets fixed. I will e-mail you a copy. There is nothing simple or easy about these critters....

 

[laatsch55]

You should have it now Jer.

 

[Gepetto]

Yeah we might want to "Call a Joe" in on this one, hehe... I have the SM, and at least from one of the revisions we basically see that

1. There are 10 total TO3 cans per channel

2. 8 of which SM says MJ15024's for the top half and MJ15025's for the bottom. But .. 2 (per rail, per channel) are in one configuration like cascode, etc, while the other two are configured differently

3. The remaining two appear to be some sort of main power voltage "pass through" or switching Q's.. SM calls for MJ410 on the top/pos half and MJ6502 for the bottom.

So THAT is what the SM calls for.. but in reality...

Q3 and Q8 (the 6502 and 410) are really MJ15025 for Q3/6502 and MJ15024 for Q8/MJ410

Q1 and Q2 (should be MJ15025's, makes up the 2 Q "cascode")... are really MJ15004's

Q4 is an 024, Q5 is an 004

Q6 is an 024, and Q7, Q9, and Q10 all 003's

Q9 and Q10 are the 2 that make up the 2 Q "cascode" on the positive half., leaving Q6 as an 024, Q5 as an 004

All sorts of funky Q arranging going on. Joe if I send a skeezer your way... ???

Sure thing Jer

 

[Northwinds]

 

[laatsch55]

Need some text with those pics there big guy..

 

[Gepetto]

Jer you should normalize Q6, 7, 9, 10 as MJ15024 or MJ21196

Q1, 2, 4, 5 as MJ15025 or MJ21195

The MJ410 is really very much an RCA410 but made by Moto. The MJ6502 is an odd duck complement to the MJ410, very obscure. Use the MJ15024 or MJ21196 for Q8 and the MJ15025 or MJ21195 for Q3.

In other words, use the 15024 for all NPN locations and 15025 for all PNP locations.

It is not cascode operation it is actually an amp that switches in a power supply of +/-50V with low level signals, kicks in +/-80V when the signal gets larger (louder) and then finally the +/-125V stage kicks in when it gets even larger (louder yet).

This is a method to get away from heat generation in the heat sinks when it is not called for.

Cascode operation would have Q6 and Q7 nearly equally sharing the load at all signal levels the way 2 equal resistors in series share the impressed voltage.

 

[laatsch55]

Got some funky triac operation in the power supply too, never could wrap my head around that one.

 

[jbeckva]

Aye, what issss the amp doing with all it's "trickses"?? hmmmmm?? heheh. Yeah, it's an interesting design to say the least.

 

[laatsch55]

Joe, on the MJ21196 data sheet it lists Vceo at 250, Vcbo at 400, Vbeo at 400 volts. What rating represents the total swing of 250 volts for the hi side B+,B- rails??

 

[Gepetto]

Got some funky triac operation in the power supply too, never could wrap my head around that one.

I only looked briefly Lee, saw that too but moved on. Assumed that is the main power on function with soft start.

What a mess of a schematic.