Bottlehead Forum
Bottlehead Kits => BeePre => Topic started by: thdewitt on January 16, 2015, 07:37:00 AM
-
OK, so I finally got around to finishing my Bee Pre. I built pretty much all of the kits. This one was definitely the most involved. Everything on the resistance seems to check out fine but the voltages do not. I am not getting the bottom two LED's to light on the right side CS4. :'(
(https://dl.dropboxusercontent.com/u/38833957/2015-01-15%2020.37.35.jpg)
I have looked through the instructions and compared to the other side and can't locate the problem. Any ideas on what I can test to narrow the problem down.
Thanks
Tom
-
Post the voltages that are off. Also post the expected voltage.
-
OK, sorry it took so long I have been out for the weekend. So I am going to just post the voltages that are off since there are so many.
terminal Correct
10 178.7 186
11 182.5 146
16 0 5
17 181 90-110
22 205 213
25 205 213
29 8.1 6.8
30 8.2 6.8
31 16.3 13.6
34 12.8 13.6
40 209 213
b2 181 90-110
d3 1.9 3.5-4.5
d7 182 147
d9 180 147
Any help would be appreciated. There is something wrong with the power supply on the right side just can't seem to see it.
Thanks,
Tom
-
The 300B on that side isn't drawing any filament current, as can be seen by having 0V on terminal 16. If you have 10V or so at POS OUT on that side, then you should have 10V going into the 300B, passing through the 300B filament, then traveling through the paralleled 8 Ohm resistors.
This could be an issue of an improperly oriented 4 pin socket, or no voltage at POS out. (Go ahead and measure it)
-PB
-
I am getting zero at the positive out.
Tom
-
How about at positive in?
-
OK, I found a broken wire on the positive in. I replaced that as somehow it had a cut. Anyway. The voltages have changed but still no light on the diodes. Here are the voltages out of whack now.
Terminal Reading Correct
10 173 186
15 175 186
17 127 90-100
22 201 213
25 202 213
40 202 213
43 202 213
46 202 213
b2 132 90-110
d3 7.0 3.5-4.5
-
What voltage do you have at POS OUT now? It looks like that 300B still isn't conducting all the way.
-PB
-
9.79 Volts.
-
Alright, that's spot on. Can I get the IA, OA, and OB voltages on the offending channel?
-
IA 174.7
OA 130.4
OB 121.8
Thanks so much Tom
-
Can you switch both the EL84 and the 300B between channels (do them both at once).
Your 300B isn't drawing current, and the shunt regulator is also not regulating properly.
-
Pretty much stayed the same
IA 174
OA 127.1
OB 121.8
Tom
-
I wrote the OB wrong. IT was 119.5
-
The next thing I would do is to recheck the IA, OA, and OB voltages with no EL84 plugged into that channel.
-PB
-
OK, here are the readings without the EL84 plugged in.
IA 180, OA 127, OB 120. So they really did not change. Is that strange? What does that mean? What does the EL84 do?
Thanks,
Tom
-
Can you confirm that the R1 resistors are the correct values?
Unplugging the EL84 removes the high voltage regulator from functioning in the circuit, which just leaves us with a couple of C4S's and the 300B. For whatever reason, your 300B on that side is not drawing proper plate current, and I believe we have it narrowed down to an issue on that C4S board.
-PB
-
They seem to be fine. Should i take them out to measure. The numbers are good and I usually measure when installing them.
(https://dl.dropboxusercontent.com/u/38833957/2015-01-20%2014.03.37.jpg)
-
I'd have a long look at the jumper and solder joints on the bottom side of the board, as well as around the 4 pin socket. You may also want to be sure that pin 3 of that 4 pin socket shows 0V when the BeePre is on.
-PB
-
OK, now I am really frustrated. I took the CS4. Put in new jumpers following the directions in the manual. While it was out, I carefully inspected the manual pages and the 4 pin to make sure it is right. I did notice that the wires on pin A1 and B4 are the only ones that are not symmetrical but that is the same as the manual. I reflowed all the joints on the 4 pin and surrounding connections. I reflowed the CS4 again. I then put it back together and there was no change. The LED's are still not lighting. I am stuck. Are there any readings I can take to further check the board to find if one of the components are faulty.
Tom
(https://dl.dropboxusercontent.com/u/38833957/2015-01-20%2015.38.14.jpg)
-
I also put in a good 300b from my paramounts. The voltage at b3 is zero while on.
-
Try reheating the center leg of the MJE5731A on the B side of that C4S board.
-
Ok. But I have reheated them all twice.
-
OK, I did it. The led's still not lit. :o :'(
-
Heat the solder joint at 11 and remove the wire heading back to the EL84 so that it's out of the t-strip and floating in the air, then retest.
-
Hello, before I got your last post, i removed the whole C4S and swapped to the other side. So now the problem has moved to the other side so it is definitely in the wiring of the board or something on the board. The C4S moved to the B side worked fine. So the problem followed the board. Should I still try the test that you just posted based on the new information.