phase linear 400

[gene french]

yes sir...i am trying....the diodes tested good...
so, i figured it had to be down the line somewhere...
of course i dont have those...i do have the diodes...
i will look....

 

[Gepetto]

yes sir...i am trying....the diodes tested good...
so, i figured it had to be down the line somewhere...
of course i dont have those...i do have the diodes...
i will look....

The diodes always survive...

 

[gene french]

The diodes always survive...

yes sir...

 

[Gepetto]

I imagine MPS651/751s are pretty scarce in Costa Rica...

 

[gene french]

q7 and q8 both test ok...in circuit...
wow....

 

[Gepetto]

q7 and q8 both test ok...in circuit...
wow....

But did you test the C-E junction of each in both directions?

 

[gene french]

But did you test the C-E junction of each in both directions?

i tested b to c ...b to e...reverse leads b to c and b to e....then i checked c to e...but not both directions...
i will go do it again...i did not know i had to check both directions...

 

[gene french]

ok....
c to e in one direction is out of limits
e to c in the other direction reads 2.2 v
both transistors...

 

[Gepetto]

i tested b to c ...b to e...reverse leads b to c and b to e....then i checked c to e...but not both directions...
i will go do it again...i did not know i had to check both directions...

Something is clamping your bias down in that circuit. You proved that by lifting the diode ends. The only practical possibilities are those 2 transistors and the 1 ohm resistors.

 

[Gepetto]

ok....
c to e in one direction is out of limits
e to c in the other direction reads 2.2 v
both transistors...

And did you compare those readings to your functional right channel?

 

[gene french]

And did you compare those readings to your functional right channel?

i will compare the transistor readings side to side

 

[WOPL Sniffer]

161 pages and counting.

 

[Gepetto]

161 pages and counting.

So far, lots of Boom along the way

 

[gene french]

 

[gene french]

does not match what i have...

 

[Gepetto]

With a Fluke 179 meter, on the diode scale, C-E reads open in both directions in circuit.

 

[Gepetto]

does not match what i have...

As Perry says often... HUH??

 

[gene french]

did find this...
i think its all correct

 

[Gepetto]

What do you think is not correct? The BOM snippet you included above is from the Quasi Comp section of the BOM. The first 12 pages document the quasi-comp build and the last 12 pages document the full comp build instructions. You can tell which is which by the header on the page...

 

[Gepetto]

Your board is assembled correctly...