Thanks for a very detailed and useful answer Mark. I'll reach out in the De-Noiser thread.
I really appreciate all the extra info given and the reasonings behind your suggestions. I actually will add that Logwell table to my 'go to' resources, I already have the Nichicon diagram you posted here or elsewhere (cannot keep tags of where things are!) as my go-to reference for picking up capacitors. Thanks!
Still, with jimk04's offering, I may be saved, it's the only thing missing in the BOM, so I should be set. Jimk, as I have mentioned in many places, things delivered here is a complex issue, and I employ a service to import things from Miami. But they charge for every package they receive, so if Amazon decides to send two shipments instead of one, even if one of those is just a bolt, then that gets charged the minimum package, which is $11. So, that BC337 alone would cost me $11 and tbrooke's PCB another $11... but if you send the PCB and the BJT together, those two would be just $11 for both, so it's much more practical.
So, with thanks to tbrooke, I'll accept Jimk's offer just as soon as I can secure a Transformer and a few other minor things I need.
Thanks so much for all the help, guidance, offers and just great attitude!
Big hug,
Rafa.
I really appreciate all the extra info given and the reasonings behind your suggestions. I actually will add that Logwell table to my 'go to' resources, I already have the Nichicon diagram you posted here or elsewhere (cannot keep tags of where things are!) as my go-to reference for picking up capacitors. Thanks!
Still, with jimk04's offering, I may be saved, it's the only thing missing in the BOM, so I should be set. Jimk, as I have mentioned in many places, things delivered here is a complex issue, and I employ a service to import things from Miami. But they charge for every package they receive, so if Amazon decides to send two shipments instead of one, even if one of those is just a bolt, then that gets charged the minimum package, which is $11. So, that BC337 alone would cost me $11 and tbrooke's PCB another $11... but if you send the PCB and the BJT together, those two would be just $11 for both, so it's much more practical.
So, with thanks to tbrooke, I'll accept Jimk's offer just as soon as I can secure a Transformer and a few other minor things I need.
Thanks so much for all the help, guidance, offers and just great attitude!
Big hug,
Rafa.
Friends, I am utterly confused about the Transformer (never have used a toroid one other than the PCB mount of the Whammy, so please give me a little freeway to be extra stupid here!).
Would this be a valid transformer for the VRDN for 18V operation? (to be used in Wayne's 2018 Linestage):
- 553-VPM36-690
The instructions point to use "Output from Black & Red, jumper Black & Orange, jumper Red to Yellow", but there are 4 entry points W, X, Y and Z in the VRDN. So, which colors would go to which? I don't understand. Sorry,
Thanks,
Rafa.
Edit: Just to clarify, the transformer says "Primary and secondary windings are designed to be connected in series or parallel. Windings are not intended to be used independently."... so, would that mean, that I cannot use them as two secondaries? Or is this a usual setup? Again, sorry, very, very confused here.
Would this be a valid transformer for the VRDN for 18V operation? (to be used in Wayne's 2018 Linestage):
- 553-VPM36-690
The instructions point to use "Output from Black & Red, jumper Black & Orange, jumper Red to Yellow", but there are 4 entry points W, X, Y and Z in the VRDN. So, which colors would go to which? I don't understand. Sorry,
Thanks,
Rafa.
Edit: Just to clarify, the transformer says "Primary and secondary windings are designed to be connected in series or parallel. Windings are not intended to be used independently."... so, would that mean, that I cannot use them as two secondaries? Or is this a usual setup? Again, sorry, very, very confused here.
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Rafa. I shall send the PCB and BC337 as soon as you need them. Just say.
The trafo you link to I believe not to be suitable as it is a CT (centre tap ) arrangement. (3 wires output) . You want a 4 wire output (2 secondaries) or i believe you can use a single primary output ( 2 wires) if you use a jumper on the AC input
The trafo you link to I believe not to be suitable as it is a CT (centre tap ) arrangement. (3 wires output) . You want a 4 wire output (2 secondaries) or i believe you can use a single primary output ( 2 wires) if you use a jumper on the AC input
The 25VA is out of stock, but this will work...
AS-0518 - 50VA 18V Transformer - AnTek Products Corp
AS-0518 - 50VA 18V Transformer - AnTek Products Corp
The schematic on the datasheet shows 4 secondary wires and 6 primary wires. I think it will work just dandy with VRDN.
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Indeed, that would help a lot safe quite a bit of money. Yes, thanks!
Thanks for verifying. Indeed, it is rated as "dual secondaries"... it does have 4 secondary wires. The only "misleading" part it that it claims that "Windings are not intended to be used independently.".
Would using all the 4 secondary wires not be "using them independently"? It is that wording that confuses me (along with the fact that the instructions only provide for using "black and red, and jumpering black to orange and red to yellow, which would end up with just a single pair of wires).
So I understood that there could be some transformers which dual secondary windings are designed to be used separately and others that are not meant to. Maybe I'm just completely off.
Thanks again for all the attention to these issues.
One more thing, there is, from the same brand, an almost identical transformer, only that it is not rated as "medical grade":
- 553-VPT36-690
It costs half of what the other does, is this difference worth it? Does it make any difference in terms of audio equipment?
Thanks again, sorry for the myriad of questions, I promise they stop and some point sooner rather than later
IF MJ says you are good to go then you are good to go.
Yes, indeed! Very nice to read "Just dandy!"
Be care ful with this circuit Rafa. There were comments about oscillation and they need to be taken seriously. While the original parts/models didn't see much of this, it was problematic.
Take the time to read and make the stability changes. The oscillation was real and i was one of the first two to see it.
Work was done to stabilize the model and circuit... head those changes.
JT
Take the time to read and make the stability changes. The oscillation was real and i was one of the first two to see it.
Work was done to stabilize the model and circuit... head those changes.
JT
Yeah, thanks. I read through the entire thread, I have in the BOM both the original pieces and the suggested changes. I cannot measure oscillation, but if it never biases towards the expected voltage, that would be enough of an indicator, right?
Any of the options I have found has some singularities. But this one has a nice appeal and the DeNoiser is something I think can be a really nice addition.
Also, I really trust Mark's criteria when designing these type of circuits, so I thought if I am going to gamble in a design, best to bet on Mark's.
Thanks for the heads-up, hope things are simpler than having to debug oscillations.
Rafa.
Any of the options I have found has some singularities. But this one has a nice appeal and the DeNoiser is something I think can be a really nice addition.
Also, I really trust Mark's criteria when designing these type of circuits, so I thought if I am going to gamble in a design, best to bet on Mark's.
Thanks for the heads-up, hope things are simpler than having to debug oscillations.
Rafa.
I don't know enough to advise you more than I already have. If you do the suggested changes, after the issue was detected, you will be fine. If you don't then and use the original parts then you will still be okay... mostly. If you use the alternate parts, we did, you will likely have issues.
As I siad, read the changed=s and use them even if you are using the original schematic and parts.
As I siad, read the changed=s and use them even if you are using the original schematic and parts.
Just had a look but sorry I don't have any left. Easy enough to order but they aren't the cheapest boards to have made and I'm sure you'd soon sell on the remainder.
Looking at the single supply mod for 2 wire ac. What are the advantages/disadvantages if any of a single wave set up rather than a full wave rectifier. I have a single 18vac which could come in handy for this.
Looking at the single supply mod for 2 wire ac. What are the advantages/disadvantages if any of a single wave set up rather than a full wave rectifier. I have a single 18vac which could come in handy for this.
Hi Mark. I'm back in town and trying to pick up on the debugging of what is wrong with minus rail of my VRDN. I am using both a 100 ohm 3 watt resistor and a dim bulb tester to avoid burning up another wall wart.
All of the diodes measure essentially the same on the positive and minus rails so that seems unlikely be the cause of the problem.
I measured the voltages at the open loop ends of R4, R6, R9, And R12 All measured 0 except for R6 which measured -0.015 volts. I also was able to measure -0.015 volts on the negative side of the C4, C6, and C8 capacitors while C10 and C12 measured 0. All the other components with the open loops also measured 0. On the positive rail the measurements were about 17 volts at R3, R5, dropping to 5.5 volts at R7 and climbing to 14 volts at R11.
Finally, since my DMM permits measuring capacitance I tried to measure the capacitance of the 220uF capacitors. On the positive rail these generally measured about 12.8mF. On the negative rail I got the error message trying to measure the 220uF capacitors regardless of polarity until I got to C20 that did measure 3mF.
I did also measure the resistance of R4 and R6 and got .3 ohms as expected.
So it has been nearly 50 years since my class in circuit design and you can imagine how little of that I remember, but I'm wondering if one of my 220uF capacitors is bad? What else do you think it might be?
Thanks.
Have you tried measuring the continuity between the expected parts? This is difficult to explain, but I do it like this: if there is supposed to be continuity between a resistor and another, I measure on the upper side of the legs to ensure they are soldered properly and that the pads and traces on the PCB are making good contact with the legs on the element.
For capacitors, I put the multimeter on the sticking leg on the other side.
This helps me ensure that everything is connected as expected. I do this carefully for every component, so, stick the multimeter on the leg on one resistor and trace with the diagram to all the places it needs to have continuity... and check that each is "beeping" correctly.
That helps me a lot in knowing if I have something poorly soldered.
I know Mark already went through your pictures, but ensuring that all capacitors, diodes, and fets are installed in the correct orientation is another good check point.
I'm sorry I cannot help any more, I am usually limited to mechanical troubleshooting. If it is a failing element, I would have no idea where to start, so just adding my grain of help if it helps a lot.
Rafa.
For capacitors, I put the multimeter on the sticking leg on the other side.
This helps me ensure that everything is connected as expected. I do this carefully for every component, so, stick the multimeter on the leg on one resistor and trace with the diagram to all the places it needs to have continuity... and check that each is "beeping" correctly.
That helps me a lot in knowing if I have something poorly soldered.
I know Mark already went through your pictures, but ensuring that all capacitors, diodes, and fets are installed in the correct orientation is another good check point.
I'm sorry I cannot help any more, I am usually limited to mechanical troubleshooting. If it is a failing element, I would have no idea where to start, so just adding my grain of help if it helps a lot.
Rafa.
Thanks for the suggestion. I've done my best to trace continuity and haven't found any obvious problems but it isn't clear that I know what I am doing. Other than randomly desoldering parts and testing and replacing them I'm not quite sure what my next step would be.
I do have a second VRDN board and more parts on the way so I'll probably just build a completely new one this time using the Antek AS-0518 - 50VA 18V Transformer rather than wall warts. Hopefully that will go better.
I do have a second VRDN board and more parts on the way so I'll probably just build a completely new one this time using the Antek AS-0518 - 50VA 18V Transformer rather than wall warts. Hopefully that will go better.