The mains earth connection is not secured. Sand the anodizing off the aluminum around the bolt and connect mains directly to the chassis, stack additional connectors on top.
Thanks @Vunce, I noticed that just now going back and looking over everything carefully. The connectors are cranked down good and tight now with a nut. And you can't really see it in the photo, but the chassis is thoroughly scraped on both sides of the bolt hole for proper contact. Thanks for that catch!
One thing at a time, ZM! I'm getting there 😉missing volpots?
no Twister cable?
Can't wait to finally hear your circuit in action. It's been a long time coming...
Well, I'm stumped. Power up went fine. I'm getting 15v+/- on both channels, 0VDC+/- on the offset... but no sound. Also, no LEDs are lighting up, neither the power indicator (which I just have wired to the left channel board) or on the input selector... which has me confused since I quadruple checked the orientation before soldering. Does that explain the issue? I did just realize that I need to add a diode for the third SE input, but otherwise I think everything is as it should be. I've checked continuity on the volume pot connections, all good there. Same for the output jacks. One weird thing is that there seems to be continuity on the inputs between the GND pad on the PCB and the + terminal on the RCA jack and vice versa. Can't figure for the life of me how that is happening.
For the SE output I just wired up the GND and + pads and left the - alone. I think that's right?
Any suggestions for trouble-shooting would be most appreciated! Thanks.
For the SE output I just wired up the GND and + pads and left the - alone. I think that's right?
Any suggestions for trouble-shooting would be most appreciated! Thanks.
Jumpers? I see a jumper, but no "jump". Maybe it just needs a jump to get 'er going? I'm probably wrong though. I've never built the balanced Iron Pre....aka "The Iron Pre"
Got it. Will check the IDC header... as soon as I can pick up some new fuses, as they appear to have blown. This is the second blown set today, so maybe there's something going on there, too. The toroids are 50va (the Antek 0518s) and I'm in the US, so was using 500mA slow-blow fuses. Am I off on that calculated value?
If you are blowing fuses, you need to solve that first. You say "second set"?
Does that mean you have two fuses in the PEM? I don't see fuses elsewhere, but I could be missing them. Both blowing? Both 0A5 slow blow?
Calculation... yousa gotsa two 50VA transformers...
So, unless they're fused separately... which I don't see... but IF not
100VA / 120 => A tad higher may be better.
Me, myself and I ... IF they were not fused separately would use a 1A on the live/hot side and something like a 10A on the neutral, IF my PEM had both live and neutral fused.
Do you have a variable transformer? You mentioned that you got +- 15V before on both boards, which is great. After you install the next set of fuses, if you have a variable transformer, consider ramping up the voltage.
Does that mean you have two fuses in the PEM? I don't see fuses elsewhere, but I could be missing them. Both blowing? Both 0A5 slow blow?
Calculation... yousa gotsa two 50VA transformers...
So, unless they're fused separately... which I don't see... but IF not
100VA / 120 => A tad higher may be better.
Me, myself and I ... IF they were not fused separately would use a 1A on the live/hot side and something like a 10A on the neutral, IF my PEM had both live and neutral fused.
Do you have a variable transformer? You mentioned that you got +- 15V before on both boards, which is great. After you install the next set of fuses, if you have a variable transformer, consider ramping up the voltage.
Thanks, IAIMH. I ordered some 1A fuses to try. Didn't occur to me that I should add the VA value of the two trafos together! I'm just using the fuse drawer in the recommended Schurter PEM.
Unfortunately I don't have a variable transformer. Just a lightbulb tester with a 25w bulb. I was getting +- 15v both with the lightbulb and full AC mains.
For wiring, I followed the diagram in post 1, and the pics in Jim's build guide. So, Live (Red) from PEM to front switch to red primaries from both trafos. Neutral from PEM direct to both black primaries. Posting some pics. I'm wondering if I should try taking the front switch out of the equation to simplify things?
Thanks for all the troubleshooting help!
Unfortunately I don't have a variable transformer. Just a lightbulb tester with a 25w bulb. I was getting +- 15v both with the lightbulb and full AC mains.
For wiring, I followed the diagram in post 1, and the pics in Jim's build guide. So, Live (Red) from PEM to front switch to red primaries from both trafos. Neutral from PEM direct to both black primaries. Posting some pics. I'm wondering if I should try taking the front switch out of the equation to simplify things?
Thanks for all the troubleshooting help!
test time
edit:
first morning coffee time, so I just realized that you have single primary on your Donuts - saying that 4 primary wires are connected to IEC
that means - no use of attached pic in your case, but let it be, could be useful to someone in future
edit:
first morning coffee time, so I just realized that you have single primary on your Donuts - saying that 4 primary wires are connected to IEC
that means - no use of attached pic in your case, but let it be, could be useful to someone in future
@spryor Fantastic. If you follow 6L6's guides, you're always in the clear. In the previous picture I couldn't see the routing of the two black wires up under the PEM. Having +-15V was the giveaway that all was OK, but... just wanted to check.
Incrementally moving along... no sound ... and power LED ... twister LEDs.
Front power LED - Where are the black and white (light blue?) wire connected? What value current limiting resistor? Are you really, really sure you oriented the LED properly - did you give it a quick test before you put all the shrink tubing on? Most common issue for LEDs is not orienting properly... and many people think the cathode goes to + or the more positive side of the supply and is the long leg, and it's the opposite. Sadly, if you have power to the boards, and if the LED is connected to the boards in a proper place, with a proper current limiting resistor... the most simple thing to do is reverse the wires to check. Another (slightly less) common issue is a bit too much heat can kill an LED during soldering. If you are certain that the wiring is correct.. then the only thing left to do is replace the LED. If you used (far) too low a current limiting resistor value, that can also lead to it failing.
Twister LEDs / Sound - Are the relays clicking when you turn the input selection switch?
Incrementally moving along... no sound ... and power LED ... twister LEDs.
Front power LED - Where are the black and white (light blue?) wire connected? What value current limiting resistor? Are you really, really sure you oriented the LED properly - did you give it a quick test before you put all the shrink tubing on? Most common issue for LEDs is not orienting properly... and many people think the cathode goes to + or the more positive side of the supply and is the long leg, and it's the opposite. Sadly, if you have power to the boards, and if the LED is connected to the boards in a proper place, with a proper current limiting resistor... the most simple thing to do is reverse the wires to check. Another (slightly less) common issue is a bit too much heat can kill an LED during soldering. If you are certain that the wiring is correct.. then the only thing left to do is replace the LED. If you used (far) too low a current limiting resistor value, that can also lead to it failing.
Twister LEDs / Sound - Are the relays clicking when you turn the input selection switch?
If no - From my old renderings of the 2020 boards and the Twister board, your 14-pin connectors are oriented properly. A quick beep test will confirm continuity from end-to-end. If you've checked that the cable isn't an issue with a quick beep test, check voltage as Mighty ZM suggests.
If you hear the clicks... we'll head another direction.
Edited for clarity... and ZM was typing too. 🙂
Its almost 6:30 AM here???????
Emphasis added in the quote is mine. Those Anteks are dual primary (wired in parallel for 120VAC(ish) mains) dual secondary. 4 black and 4 red leads. One black and one red are the ends of each primary. They've got +- 15VDC on each board, so primaries and secondaries were 99% to be correct, I just couldn't see those two pesky black leads... and fuses were popping, so I wanted to be totally sure.edit:
first morning coffee time, so I just realized that you have single primary on your Donuts - saying that 4 primary wires are connected to IEC
that means - no use of attached pic in your case, but let it be, could be useful to someone in future
Edited to add... and it's second coffee time for me now...
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which I am
being awake when I must or simply want, sleeping when I must or simply want
so, when I wake up, time for breakfast and coffee; not exactly interested in time frame out of my reality bubble
