Derek92994's 700 Ser II White Oak conversion

[derek92994]

Oh hell yes!!! I tested with multimeter, no spikes. Bring it on!!!!

 

[pennysdad]

Do you have one of those little powerpoint testers?
I checked my variac with one and found the active and neutral reversed.
I don't think that makes much difference tho'.
My first one had the earth and neutral reversed.
You gotta be careful with Chinese stuff.

 

[derek92994]

Do you have one of those little powerpoint testers?
I checked my variac with one and found the active and neutral reversed.
I don't think that makes much difference tho'.
My first one had the earth and neutral reversed.
You gotta be careful with Chinese stuff.
View attachment 49411

Sure, I have one in the car, will run it.

 

[derek92994]

Yep, She”s good.

 

[derek92994]

Got some parts:

TO-92's
5 watt 100 ohm resistors
1 ohm 1/4 watt resistors
1/2 watt 30v zenerdiodes

 

[laatsch55]

Well, replace that TL 413's , then power up on the variac and check offset and bias,,,

 

[derek92994]

What voltage do you want me to set the variac to?

 

[derek92994]

Need instructions to check offset and bias, forgotten that stuff, has been a while

 

[laatsch55]

240, but start at zero and slowly through a DBT if you have one,,,

 

[laatsch55]

offset is checked at the speaker posts, bias is checked on the board..

 

[derek92994]

I dont have a DBT at this stage

 

[derek92994]

First thing first

heres a pic of the to92s i got, does it look right?

 

[laatsch55]

No biggie..

 

[laatsch55]

That is not a TL 431, That's a 78L12...let me research that...

 

[derek92994]

The 78L12 is:
12 volt 100ma
Input Voltage 14.5v
Voltage Drop 2.5v min
Regulator Polarity Positive

Edit its the only one they had, otherwise they had a 2.5 volt one which is nowhere near what we need

 

[laatsch55]

See if Mouser , Aus has some TL-431's...

 

[derek92994]

See if Mouser , Aus has some TL-431's...

Thanks Lee, Will do, and will place an order, if you think of anything else I may need, please let me know.

 

[laatsch55]

Make sure the 1 ohm resistors are 1 or 5% metal oxide (MO) or metal film (MF)...

 

[laatsch55]

And thanks for you help today bud, 50 minutes and we are done...

 

[derek92994]

And thanks for you help today bud, 50 minutes and we are done...

Anytime Lee, cheers bud!