700B blew one Right channel 5A supply fuse

[laatsch55]

To monitor bias you hook your meter leads on either side of the 10 ohm resistor on the backwall on the positive drive side(the left)...and then adjust the pot...

 

[62vauxhall]

Not with 28 volts DC on the speaker outs. Take the resistors off and check offset again...

Actually, that was with the resistors off.

 

[laatsch55]

Well then we still have a problem on the right channel

 

[62vauxhall]

To monitor bias you hook your meter leads on either side of the 10 ohm resistor on the backwall on the positive drive side(the left)...and then adjust the pot...

Thanks, sounds easy enough. Hook a meter lead to each side of the 10 Ohm (brown/black/black) resistor in the left side column of output transistors.

 

[laatsch55]

Cheeck D9,D10 on each channel again..

 

[laatsch55]

Correct Gary, remember let the caps bleed, a slip of the probe there and we'll be at this for another month....

 

[62vauxhall]

Cheeck D9,D10 on each channel again..

Unhooked a side of each one and not sure which is D9 and D10 but starting with the far left one and going right:

.394 & OL - .398 & OL - .442 & OL - .372 & OL.

 

[laatsch55]

With those unhooked dimbulb it again..check offset while you do...

 

[62vauxhall]

Correct Gary, remember let the caps bleed, a slip of the probe there and we'll be at this for another month....

I made up a short pair of short leads with insulated alligator clips on both ends - will use those.

 

[laatsch55]

No need for bias check yet...that's next..

 

[laatsch55]

I made up a short pair of short leads with insulated alligator clips on both ends - will use those.

how much exposed area?

 

[62vauxhall]

With those unhooked dimbulb it again..check offset while you do...

About the same.

For what it's worth, the bulb dimmed ever so slightly but the varying voltages were still there.

 

[62vauxhall]

how much exposed area?

 

[laatsch55]

Ok, Do you have a pair of very sharp, very small lead ends?

 

[laatsch55]

View attachment 14497

Yep, that's bleed the caps first material..

 

[laatsch55]

Nav, if you've got some advise, let's hear it....

 

[62vauxhall]

Ok, Do you have a pair of very sharp, very small lead ends?

Just what came with the meter. They're pretty sharp and they came with those removable sleeves that only leave the tips exposed.

 

[laatsch55]

OK, now we check bias, on both channels to make sure the outputs are turned on then we go from there...

 

[62vauxhall]

Yep, that's bleed the caps first material..

I've got more clips and can make up another pair with heavier gauge wire if that would help.

 

[62vauxhall]

OK, now we check bias, on both channels to make sure the outputs are turned on then we go from there...

Before I do that - reconnect the diodes?