ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Hi
Almost finished the re-cap of my BM1200. Only thing is I am totally unsure of the correct connection of the 2 3000uf caps. One had clearly marked polarity, but the other was an old original Wicon. I can not decipher its polarity marking. I attached the multimeter to determine polarity but do not trust the outcome. Rather than run the risk of blowing up my hard work, I am posting to see if some one can tell me which wires (yellow, green; orange, blue) go to positive and negative (obviously the new caps are clearly marked). Here is the story so far-
Original BM1200 caps. The right hand cap is clearly marked, so I copied that for the new cap. The left cap is not clearly marked so I measured the DC across the connectors. That suggested the right connector is +ve. This is the initial information I followed when connecting the new caps...
1200 initial connection based on multimeter reading of DC across old Wicon cap (which I do not trust). yellow-, green+; orange+, blue-. This did not feel right, so I also measured the DC across the clearly marked old cap. I got a -ve reading when red was connected to + and black to the black connection; strange. Danger, danger!!! Time to reference my working BM1001...
My BM1001, which I just opened up for reference. The polarity of these according to my multimeter (DC reading) is yellow+, green-; orange+, blue- That would seem to be logical. Is this correct?
Thanks for the advise!
Love = My Beomaster 1001 + Beovox 2700
I have same operation ahead. Do yuo happend to have list of caps neede?
blah-blah and photographs as needed
Usually, the square (and triangular in double caps) marked pins are positives.Doesn't it say "Plain Neg." on the old cap ?
Martin
The cap does read 'plain negative.' I looked that up on line and found a guy who had the same challenge as me on a different amp. He concluded the flatter/simpler pin was +ve. that contradicts my DC reading on my working BM1001. What does 'plain negative' mean?
There is a slight difference between the pins in the BM1001 (Last image above). The left looks like a slightly smaller diameter and has an impression in it. The right is slightly flatter.
Hi Orava - I simply got my cap kit from Dillen (he has posted below. You could PM him). Comes with simple visual instruction.
I also referred to the user manual to help locate pins on the back of the PCBs and will use in a while to adjust the trimmers.
OK, sat down with the service manual this evening -
Using the PCB diagram (and looking at the actual PCB), I can see that the yellow wire goes to TR36 and the orange to TR38:
Then looking at the circuit diagram I could see that T38 goes to the Left Speaker cap +ve and T36 goes to the Right Speaker cap +ve. So, orange and yellow will connect to the cap +ve pins. Using the PCB diagram (above) and following from the speaker connections back to the caps confirms the blue and green wire connections:
So I will be switching my yellow and green wires around; which matches my readings off my working BM1001.
Eureka?