Bottlehead Forum

Bottlehead Kits => Crack => Topic started by: mike langer on August 26, 2016, 05:24:55 AM

Title: crack transformer
Post by: mike langer on August 26, 2016, 05:24:55 AM

Good morning,
I am starting a complete rebuild of my first crack kit[did a very bad job]
I have all new parts,etc except for original 120v trans.I am concerned that i have damaged the trans thru overheating the contacts and i can not see a connection to terminal 7.
is it possible to test the naked transformer for correct operation. This is my first build and i am not experienced.I sent photos to Doc for his opinion. Does any body have any suggestions?[aside from a new hobby!] You have all been great thanks mike.

Title: Re: crack transformer
Post by: Paul Birkeland on August 26, 2016, 06:46:51 AM

Yes, you can test the power transformer for proper operation.  When you get to page 18, and you've finished the first instruction on that page, you can put a fuse in and apply power to the transformer.  You can then measure AC voltage between each pair of terminals, and they should all read a bit higher than the sticker indicates.

If you have no connection to power transformer terminal 7, the amplifier will still work properly. 

Title: Re: crack transformer
Post by: mike langer on August 26, 2016, 09:04:37 PM

Caucasian Blackplate,
Thank you for the testing method on the transformer.Which sticker with numeric indicators are you referring to? my trans no longer has a sticker affixed to it.
Thanks again,mike

Title: Re: crack transformer
Post by: Paul Birkeland on August 27, 2016, 10:15:30 AM

You will need to refer to the manual if the sticker is no longer on the transformer (there are many pictures of the sticker in the manual).

-PB

Title: Re: crack transformer
Post by: mike langer on August 27, 2016, 11:22:43 PM

Thanks RB,i went thru the manual again and also the gallery-the values i found are:
trans term 1=0v
                2=120v
                3=none
                4=0v
                5=6.3v or 63v [could not see clearly]
                6=150v
                7=not needed
                8=none
                9=150v
                10=0v     are these values correct? and please clarify term 5
while testing live acv where should i attach the ground probe extension alligator lead?
Thank you for your continued good natured assistance,mike

Title: Re: crack transformer
Post by: Paul Birkeland on August 28, 2016, 09:40:45 AM

Quote from: mike langer on August 27, 2016, 11:22:43 PM

while testing live acv where should i attach the ground probe extension alligator lead?

To meausre the AC voltages, the red and black probes need to connect to each pair of terminals.  Red to 4, black to 5 to test terminals 4 and 5, etc.

-PB