Bottlehead Forum
Bottlehead Kits => Eros Phono => Topic started by: bradtsakeris on July 20, 2023, 05:50:50 AM
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Hello,
I have completed all the steps of the EROS 2 and am doing the final voltage check. I am not getting the correct voltage on OC, OD, OkA, OkB, OkC, or OkD. I have uploaded a picture of the board to see if there is anything you notice I did wrong.
Thanks,
Brad
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For every solder joint on that board that doesn't have an LED, you need to use a lot more heat to get the solder to flow into the through hole on the board. It also helps greatly to actually post the voltages you're seeing at each terminal.
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Hi Paul,
I am getting the following voltages from each terminal
IA = 217.8
IB = 220.3
OA = 215.2
OB = 140.1
OC = 100.2
OD = 102.5
OkA = 6.86
OkB = .4
OkC = 25.7
OkD = 4.7
What temperature should i set my solder to? I have been using around 650 degrees but my solder can go up to 850 degrees.
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850 degrees.
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Hi Paul,
I have re-soldered every joint on the C4S board and am still getting the same voltage readings as listed below. Any thoughts where I should go next?
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Post another photo of the PC board?
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Hi Paul,
I removed all of the wires to be able to remove the C4S board and flip it upside down so I could re-solder all of the holes. I have attached a picture for you to see. I then re-soldered the wires in the correct holes and ran the voltage check Here is what I'm getting now.
IA = 287.7
IB = 288.1
OA = 286.9
OB = 286.6
OC = 208.2
OD = 208.1
OkA = .5
OkB = .4
OkC = 3.51
OkD = 20.0
Any thoughts on what to do now?
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Double check that all of your tubes are glowing. The EF86 tubes will be hard to see the glow from. A very dark room is helpful.
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Hi Dan,
None of the tubes are lighting up. Not sure why that is. I was at least getting the 12AX7 to light up before. I just removed the fuse and checked the volts and I'm getting 0. It looks like it may have blown.
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Hey Brad, after our conversation today I picked PBs brains a bit about what you were measuring on the heater supply. He suggested that maybe either the 124 ohm Rset1 resistor or the 499 ohm Rset2 resistor has the wrong value installed, or perhaps they are correct but need a bit of a solder reflow. Makes sense and I should have thought to mention that. So you might have a look at those. They are just inboard of the LM1085 chip.
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Hi Dan,
I re-soldered all 3 boards to make sure they all have solid solder on every joint. I installed all of the tubes and they are still not lighting up. I checked the voltages and am getting the following readings:
IA = 301.9
IB = 301.9
OA = 299.5
OB = 299.6
OC = 210.5
OD = 206
OkA = .81
OkB = 6.9
OkC = 3.27
OkD = 20.1
These readings are all way higher than the last readings. I'm sure where to check from here. Let me know your thoughts.
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If the tubes aren't glowing, the high voltage readings don't really matter nor do they mean anything. You have to focus on getting 6.3V DC across the + and - pads on the low voltage output section of the power supply board. Until that is correct, the tubes will not light up and the high voltage readings will be wacky.
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Hi Paul,
I am getting a reading of 3.12v & 1.86v at the 6.3v DC. Thoughts on where I should look next?
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Take the power supply PC board off and send photos of the top and bottom. Also triple check that the 1085 regulator is installed instead of a 5731A transistor, as they both look similar.
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Hi Paul,
Here is a picture of the top of the board. I'm hoping you notice something here before I go an un-solder all the wires to be able to show the underside. Let me know thoughts.
Best,
Brad
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If you pull the tubes out, do the voltages at the 6.3V pads change?
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Paul,
I just pulled the tubes and am getting a reading of 30.8 on the + and 30.6 on the - of the 6.3V
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There's all sorts of wrong with this. Can you slip just the shielded twisted pair connections out of the + and - pads where the 6.3V is supposed to be and recheck those outputs?
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Paul,
Sorry, I'm a bit of a newbie with all this stuff. Do you want me to remove the shielded wire from the board at the 6.3v? What do I need to do after doing that?
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Let's slow this down. Don't remove the wires yet. If you recall I explained during our phone call that you want to measure with black test lead to 6.3v - and red lead to 6.3v+. For this measurement you don't want the black lead connected to the ground post. Give us that reading from 6.3+ to 6.3- . And please let us know if you double checked the values of the 124 and 499 ohm resistors mentioned in my previous post.
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Hi Dan,
Sorry, I should have been more clear on my end. I'm getting 3.12v on + and 1.86v on - when I have the black lead connected to the ground post. I am getting 30.8 on + and 30.3 on - when I have both the red and the black touching the 6.3v. I also checked the 124Ohm and the 499Ohm and both are reading correctly.
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This still isn't making sense, you should put the red lead on +6.3 and the black lead on -6.3 at the same time and report the DC voltage you get there (not two different voltages).
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Paul,
My bad. The reading with red on red and black on black of the 6.3v is 30.8. I could explain the 30.3 reading but you'd probably call me an idiot, haha.
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Hi Guys,
Quick update. I noticed in the picture with all the finished wiring that I had the wiring incorrect coming from the where the power cord gets plugged in to the on/off switch. I went ahead and re-wired and have attached a picture ( I accidentally put both the switched in backwards when I first got started on the kit). Anyway, I'm still not getting proper voltages on the 6.3v but at least wanted to show we can cross this off the list.
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Your meter is set to DC volts when you check those 6.3V pads, yes?
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Hi Dan,
Yes, the meter is on DC. I just did a bunch of different tests of the 6.3v and here are the readings:
1. Tested with tubes in, turned on, and plugged into outlet.
52.6v on + (black wire on ground)
51.7v on - (black wire on ground)
1.26v with red on + and black on -
2. Tested with tubes removed, turned on, and plugged into outlet.
13.86v on + (black wire on ground)
1.85v on - (black wire on ground)
11.3 v with red on + and black on -
Let me know what I should try to do next.
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OK, this has circled back around pretty close to what you were measuring when we were on the phone. The 52v is good and indicates that the regulator that biases the heater supply up is working fine. But the 13v means something is not right with the regulator circuit for the 6.3vdc heater supply itself. That the heater voltage drops so dramatically when tubes are installed seems to imply something is not installed correctly because it's not functioning as a regulator and also not able to pass enough current to the tube heaters without the voltage getting pulled away down. If the 124 ohm and 499 ohm resistors are installed in the right positions it makes the lm1085 chip a suspect in my book. Let's see if PB concurs before you take anything aprt.
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Take the power supply board off, flip it over, then post some pictures of what the bottom looks like. Also take a picture of the 1085 regulator and post it as well.
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Hi Paul,
Here is a picture of the the underside of the board and the 1085 regulator.
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I would reflow the joints on the 1085 and the two resistors by it. The top side of the board shows that the solder has not been heated enough to flow through the board.