| Posted by stephen zaneteas | September 22, 2014 - 02:09 pm |
| Hello again.....ok....i did it this way. Via the regulator/regulator bypass cap/hum balance, 2 lines branch out to the two 5 ohm resistors seperately. Each leg goes to one channel each as you described. To sum up-the line from the CAP/HUM point goes to input side of resistor. Output goes to pin# 3. Same for other channel. Am I correct with this? You see, making a seperate power supply as i did makes things a little more complex with the wiring. Let me know if you think this is ok..... |
| Posted by Dave | September 22, 2014 - 01:31 pm |
| Hi Joe --The first thing that comes to mind involves the new speaker output connectors. With the unique center speaker connections of this amplifier, confusion may have arisen around this part of you modifications. Make sure that the black leads of the output transformers are firmly grounded. Also, make sure that the Common terminals of your new output connectors are in fact firmly grounded as well. These are normally grounded through the center channel speaker connections which are normally shorted out when no center speaker is used. I mention this as I don't know if you retained the center channel speaker connections or not when you changed out the speaker connectors. Finally, make sure that the NFB connection is still made to the 16 ohm (yellow) leads of the output transformer. This connection was normally made at the 16 ohm terminal on the old speaker terminal board, but if they have been removed, then you will need to make that connection in some other way -- just so long as the connection is maintained. I hope this helps! Dave |
| Posted by Dave | September 22, 2014 - 12:06 pm |
| Hi Stephen -- For clarity: In each channel, pin #3 of the two output tubes are connected together with a wire; therefore, the two tubes for the left channel are connected together, and the two tubes for the right channel are connected together. Then, from terminal #3 of ONE output tube in each channel is connected one end of a 5 ohm resistor. The other end of these two resistors are connected together, and then connected to the regulator/regulator bypass cap/hum balance control point. Therefore, you will need a tie point near/around the output tubes to tie the two 5 ohm resistors to, as well as a lead from that point running back to the regulator circuit. You could use the spade lug option I mentioned earlier for that connection point. I hope this helps! Dave |
| Posted by Joe Janus | September 22, 2014 - 11:56 am |
| Completed EFB, PC-10 and PC-11 replacement using Pacific Audio Regenesis that George provided a few years back... BIG improvement... but of course I had to go for more tweaks, remove tone controls, etc. but the last one, 3-prong grounded power cord and replacing the speaker output lugs has left only a hi pitched hum(feedback) coming from the speakers.... even with the input wires coming from balance control disconnected from pc-10, this hum is present and uneffected by selector switch, Volumn and/or any other control or switch... The grounds looks good and have not been changed... Any suggestions on where a guy with little theory and a bit of hardware skill might start on this issue? |
| Posted by Dave | September 22, 2014 - 11:55 am |
| Hi Ed -- Your pot is perfect. The control dissipates less than .01 watt, so a .5 watt unit is plenty big! Dave |
| Posted by stephen zaneteas | September 22, 2014 - 11:41 am |
| Hi again DAVE..I connected one pair of output tubes to the 5 ohm resistors via the regulator/regulator bypass cap/hum balance. (using terminal clocks)How would you connect the other 5 ohm resistor to the other pair of output tubes? Should I take a tap from pin #3(first pair connnected) and connect to the second 5 ohm resistor then connect resistor output to pin #3 ON THE second pair of output tubes? Im a little confused. |