Derek92994's 700 Ser II White Oak conversion

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.
Screen Shot 2021-03-20 at 2.01.09 pm.png
 
Last edited:
pennysdad said:
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
Click to expand...

Sure, I have one in the car, will run it.
 
Got some parts:

TO-92's
5 watt 100 ohm resistors
1 ohm 1/4 watt resistors
1/2 watt 30v zenerdiodes
 
Well, replace that TL 413's , then power up on the variac and check offset and bias,,,
 
What voltage do you want me to set the variac to?
 
Need instructions to check offset and bias, forgotten that stuff, has been a while
 
240, but start at zero and slowly through a DBT if you have one,,,
 
offset is checked at the speaker posts, bias is checked on the board..
 
First thing first

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


FB2DB343-711A-465B-9DDC-38032D98B83E.png
 
That is not a TL 431, That's a 78L12...let me research that...
 
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
 
Make sure the 1 ohm resistors are 1 or 5% metal oxide (MO) or metal film (MF)...
 
And thanks for you help today bud, 50 minutes and we are done...
 
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