Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Foreplay III => Topic started by: John EH on June 25, 2013, 01:10:37 AM
-
Everything good up to terminal 12.
All resistance readings ok.
No LED's anywhere with power.
Both A side and B side (all corresponding terminals).
12 - 180V supposed to be 150
15 - 1.5V supposed to be 75
Just to aid in the troubleshooting I did foul up an HLMP-6000 and subbed it. Left one on the A channel. Same LED I subbed out in the old Foreplay 2 C4S.
I know it is the regulator. I used the tube in the kit. I'll swap it next just to make sure.
John
-
Just for clarity these voltages were taken at 100V mains input.
I went to 120 and got basically 220v on 9 and 10, both power supplies. Seems the 220 is going straight to 12,21, and 32.
Terms 15 and 31 are 1.6 volts.
Term 22 - is now 40volts.
Gotta be the regulator but I swear it is together right. I took a meter to the LED's and they seem to be installed correctly. But I'm game for somebody telling me I'm wrong.
Maybe a stupid mis-wire? I don't see it.
John
-
And one more note. I have another operational Extended FP3. The diodes on the regulator board match up with the operational one. A channel red on left, black on right gets 1.8 v across with the fluke, same on the other bad one. Swap the black and red and the B channel is the same as the other one as well.
Good FP and Bad FP mirror in regards to the LED but something is letting B + pass unregulated.
Stupid wiring error? Bad transistor?
John
-
Yes, your regulator isn't working. On the center board, what are the voltages at IA/IB, OA/OB, and KregA/KregB?
Triple check all those transistors!!!!
-
Yes, your regulator isn't working. On the center board, what are the voltages at IA/IB, OA/OB, and KregA/KregB?
Triple check all those transistors!!!!
A and B
I - 186
O - 185
K - 1.1
Next I'll take photos of the transistors so I can read them.
John
-
Measurements above taken at 100v mains and reflect voltages from my first post before I upped to 120v mains.
I took macro photos of each transistor. I have the correct ones installed in the correct orientation.
-
Alright, this is helpful info!
So what I can see is that you're presenting 185V to the plates of each 12AU7, and getting a cathode voltage of 1.1V. This would be consistent with that center 12AU7 sucking down all the available current possible, and not giving the TL431 enough voltage to operate. On the other hand, the four LED's on that board should be glowing brightly.
What I would double check first is that you have continuity (~0 Ohms) between every pad labeled G on that board and ground in the amp (the bare buss wire running around the front row of terminal strips is a good ground reference). Ground passes "through" that board, so you could check continuity from terminal 24 to the ground buss.
Let me know if any of this points out issues. If not, I have some other tests that you can run.
-PB
-
.3 Ohms from both sides of the jumper labelled G on the boards to chassis ground. That's good.
-
Alright, so the center shunt reg board is grounded, receiving power, and there is some voltage present at the 12AU7 cathode.
Now we will be interested in the outboard boards, as we really, really want them to draw some current so the center board can work properly.
First of all, we want to see that the outboard 12AU7's are glowing (seems obvious, but just good to check).
Next, a red wire runs to the "A" side on each of the outer green PC boards to the "I" pad. Measure the voltage here, it should be your ~180V.
A black wire runs to the "B" side on each of the outer green PC boards to the "I" pad. Measure the voltage here, it should be 0. Measure the resistance between these pads and ground, it should be nearly 0. (0.3 in your case)
This would confirm that you have voltage coming into that board. Next, I would want to ensure that the "G" to "G" jumpers are present.
Lastly, if everything above checks out, you can be very suspicious about the LED orientation.
-PB
-
Alright, so the center shunt reg board is grounded, receiving power, and there is some voltage present at the 12AU7 cathode.
Now we will be interested in the outboard boards, as we really, really want them to draw some current so the center board can work properly.
First of all, we want to see that the outboard 12AU7's are glowing (seems obvious, but just good to check).
Next, a red wire runs to the "A" side on each of the outer green PC boards to the "I" pad. Measure the voltage here, it should be your ~180V.
A black wire runs to the "B" side on each of the outer green PC boards to the "I" pad. Measure the voltage here, it should be 0. Measure the resistance between these pads and ground, it should be nearly 0. (0.3 in your case)
This would confirm that you have voltage coming into that board. Next, I would want to ensure that the "G" to "G" jumpers are present.
Lastly, if everything above checks out, you can be very suspicious about the LED orientation.
-PB
The 12AU7's are NOT glowing.
Red wires on A on both C4S "I" points - 184V
Black wires on B on both C4S "I" points - 0V
A - "I" to ground = OPEN (this is expected)
B - "I" to ground = .03 ohms
All G to G jumpers installed on all three boards.
John
-
12AU7's are NOT glowing.
Oh, well, that will cause some problems!
There is a terminal strip back by the RCA jacks with a blue capacitor on it, this is responsible for making the tubes glow. You should see roughly 6V across that blue capacitor, that is a good place to start.
This 6V feed will also be present across tube socket pins 4/5 (they are connected together) and pin 9. This can be a little tougher to check with a meter, but often times you can peek around and find a broken wire in there.
-PB
-
12AU7's are NOT glowing.
Oh, well, that will cause some problems!
There is a terminal strip back by the RCA jacks with a blue capacitor on it, this is responsible for making the tubes glow. You should see roughly 6V across that blue capacitor, that is a good place to start.
This 6V feed will also be present across tube socket pins 4/5 (they are connected together) and pin 9. This can be a little tougher to check with a meter, but often times you can peek around and find a broken wire in there.
-PB
Paul,
You're the man. You wouldn't believe it or maybe you would. The negative wire coming from terminal 1L wasn't broken, wasn't hanging out, just loose inside the terminal. Reheated it and I got both C4S lit. The regulator board LED's aren't on but the regulator voltage dropped to 160 and I don't have my 6v on 4 and 9 on the regulator socket so I know it is the jumper added in the kit from reg socket to B socket. I have to troubleshoot that.
Will let you know if I achieve sonic success or let you know what my next problem is. Thanks!
Stupid ground wires.
John
-
OK I spoke too soon. I have all tubes lit and still no regulator board LED's lit.
Terminal 15 has 100v
Terminal 31 has 75v so it seems one side is working.
Both 12 and 32 are a little high at 165, and 170 respectively.
Both "K" pads on the regulator board are at 1.9v
John
-
Alright, things are getting better, feel free to post the I/O voltages on the center PC board (when that tube is glowing).
I guess the ~1V that was there was being fed out from the TL431 and the voltage divider.
I think you're pretty close now.
-PB
-
A side
I - 172v
O - 165v
B side
I - 167v
O - 162v
-
I resoldered every hook up wire on the regulator board and now I have faint glow in three LED's. Voltages are the same.
John
-
Can you do the I/O pads on each of the outboard boards as well?
Is the center 12AU7 glowing? It would appear to not be operational at this point.
-PB
-
Can you do the I/O pads on each of the outboard boards as well?
Is the center 12AU7 glowing? It would appear to not be operational at this point.
-PB
Regulator 12AU7 is glowing
Left Board
A side
I - 162.7
O - 95
B side
I - 0
O - 96
Right Board
A side
I - 163
O - 75
B side
I - 0
O - 78
Obviously I need to see why I'm not getting any I voltage on the B sides.
-
Check to see if you have all of the jumpers on the boards. It is pretty easy to miss one.
-
All jumpers installed. 5 on the reg board and one each on the grounds of the C4S boards. All ohm out ok.
-
The "I" on the B side is the ground, don't look too hard into that ;)
At this point, you could actually listen to your preamp, which is good, but the regulation is still off.
Is there any way you can post a photo of the center C4S board?
Also, it is good to double check that the wires leaving the Kreg pads are going to the appropriate tube socket pins.
-PB
-
Yeah I saw that when I saw the wire running to the center tube socket! Ha ha.
It's working and sounds damn good.
Stand by for the photo
-
Photo. Only thing of note is the LED I subbed which I mentioned in the first post. Radio shack 276-026a.
-
Oh yeah K wires go to R3 and R8
-
In the photo the B end upper LED is the one not lit. The other three are very dim. My subbed LED is dim. Ohm meter diode setting says they are installed correctly.
I followed the trace at the top of the board to the last LED leg in the line and got 1.8v with the diode checker.
They all seem to have 166 (or so) volts on both sides of each one.
-
Oh yeah K wires go to R3 and R8
Yes, they should, but if you have them switched, things fall apart.
You can set your meter to the continuity beep, then put one probe on + on the A side. Either pin 1 or pin 6 will beep for that connection. Now move your probe to the K pad on that side, then move to the accompanying cathode (3 for 1, 8 for 6) and you should get continuity.
If they are switched, the regulators can't keep things in balance.
That dim LED could be from the adjacent R1 not being well soldered.
-PB
-
Oh yeah K wires go to R3 and R8
Yes, they should, but if you have them switched, things fall apart.
You can set your meter to the continuity beep, then put one probe on + on the A side. Either pin 1 or pin 6 will beep for that connection. Now move your probe to the K pad on that side, then move to the accompanying cathode (3 for 1, 8 for 6) and you should get continuity.
If they are switched, the regulators can't keep things in balance.
That dim LED could be from the adjacent R1 not being well soldered.
-PB
On + pin one beeps. Moving to K makes pin 3 beep.
I'll reheat the R1's
-
Reheated the R1's and K's. Same same. 3 dim LED lights. Voltages the same.
-
Regulator tube PLENTY hot too
-
Can you swap in a different 12AU7 to the center socket? Everything looks just spot on, but the 12AU7 is not cooperating.
-
Great minds think alike. I just rolled in a couple different known good tubes. I have a TV7 tester.
-
I should have added that it didn't fix the problem.
-
You don't happen to have a pair of PN2907's instead of TL431's?
It's odd, something is not allowing the plate to pull current from the cathodes. I'd say double check that the grids on the 12AU7's are grounded (through those 220 Ohm resistors), but even if those floated up, your Kreg voltages would be higher than 1.
-PB
-
You don't happen to have a pair of PN2907's instead of TL431's?
It's odd, something is not allowing the plate to pull current from the cathodes. I'd say double check that the grids on the 12AU7's are grounded (through those 220 Ohm resistors), but even if those floated up, your Kreg voltages would be higher than 1.
-PB
Not sure what you mean. I do have two 2907a's as Q1 as per the manual
The two regulator chips are LM 431 also per the manual. The photo I posted before shows.
I'm starting to think I for sure have one bad LED. When I put the meter across the LED's individually I can get them to light up. One absolutely will not and then of course I have the subbed LED.
Would one crap LED cause the regulation problem?
I asked Eileen to send me four new ones via email earlier. Right track? Wrong station?
-
Well, you can have one regulator that's totally not working, but the other side should still be spot on.
There is something either missing on that center PC board, or something very wrong with the center 9 pin socket. Can you triple check that you get 6V from 4/5 to 9 on that center tube socket?
Can you twist that board up vertically a bit and snap a 2nd pic? (I've been staring at the first one for over an hour now, lol)
-
Hold up a sec on the pics. I'm on roll. One in a row. I removed that bad LED on the B end and sure enough I have the B end lit up brightly now.
I suspect the subbed LED in the A end is dead too. My daughter says she can't see a peep of light on it when I cross it with the diode checker.
Cross my fingers. And yours.
-
How 'bout dem apples. All LED's lit. Once Eileen sends me the new ones I'll put the HLMP's in.
One more question.
12 - 155v
15 -99v
21 - 163v
32 - 75v
Is that any kind of a problem or varies with the tube?
Thanks for all your help. I do really appreciate it.
-
You can check those by swapping the outboard tubes.
What are the voltages at I/O/Kreg pads on the center PC board?
-
You can check those by swapping the outboard tubes.
What are the voltages at I/O/Kreg pads on the center PC board?
Sorry had to go outside and live life away from the soldering iron a bit.
Here's what I have and factor in that I hooked to my main stereo system and my mains power there is now 120 where everything I fed you before was 100v mains.
12 -150
21 -150
15 -70
15 -80
A side
K -2.2
I - 215
O - 150
B side
K - 2.3
I - 217
O - 150
I'm good right?
Thanks again so much. It sounds stupid great. Better than my other Foreplay 3 Extended. Not sure why that is but it's good!
John
-
You're right on the ragged edge of where the TL431 will opeate. I think you'll want to see 3+V on Kreg, but we can now see that it's over 1V, so the 12AU7 cathodes are spewing some electrons.
I'd swap in another 12AU7 or two and see if you can get that voltage to pop up a bit. If all your 12AU7's are behaving in the same manner, I would replace the TL431 regulators (I've blown my fair share of them, they are an amazing chip, but somewhat sensitive).
-PB
-
Awesome.
Since Eileen is going to send me some more LED's I just emailed her and asked her to throw a couple 431's in as well.
Thanks a lot Paul for all your great help! I'm listening now and it sounds perfect!
And it is quieter than my other EX FP 3! This one will go in the upstairs system that has the Paramours and the SEXy Speakers because obviously it has more sensitivity.
John