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goldenreference high voltage power supply (GRHV)


Pars
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3 hours ago, audiostar said:

I am using the C3M0350120D as a replacement part for the C2M1000170D in the GRHV in my CFA Electrostatic without any issues. But this part seems to be unavailable now as well. Remarkable how one needs to wait a year for parts now.

May be in power it is ok, but I'am looking for Carbon. As kevin gilmore said - only original parts:

 

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  • 3 weeks later...

Any recommendation for connecting LED for power on/off indication to a GRHV-only based CFAE amp?

A possibility would be to connect a 3V LED to 230V AC through a 1N4007 and a 56k resistor. I don't like using those power switches with integrated lights. 

Any other or better ideas? The CFAE only has a GRHV and 230v mains, unfortunately no LV.

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On 10/18/2021 at 11:36 AM, johnwmclean said:

FWIW the C3M0350120D did not work out in a recent GRHV/Carbon I had all sorts of funky behaviour.

John, thanks for reporting! Did you used it in the amp section as well or only in the GRHV? I have the feeling that the GRHV alone could be happy with it, but probably not the Carbon.

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I used the C3M0350120D in both the Carbon and GRHV.

On the bench I tested the amp boards separately and they worked fine along with the GRHV.
In the final build with 2 amp boards connected there was oscillation which caused all sorts of odd voltages, namely 400V over the outputs and a GRHV + rail that read 8V. Funnily enough I could get the amp working with the capacitive load of a dvm killing the oscillation when probing over the GRHV outputs and I had music.

I replaced everything back to C2M1000170D and all was stable. To be honest I haven’t done enough testing to know whether the GRHV with the C3M0350120D would be ok in the field or not. But hopefully you can gain some insight from my experience with it.

Edited by johnwmclean
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  • 4 weeks later...
On 10/20/2021 at 12:12 PM, johnwmclean said:

 

I used the C3M0350120D in both the Carbon and GRHV.

On the bench I tested the amp boards separately and they worked fine along with the GRHV.
In the final build with 2 amp boards connected there was oscillation which caused all sorts of odd voltages, namely 400V over the outputs and a GRHV + rail that read 8V. Funnily enough I could get the amp working with the capacitive load of a dvm killing the oscillation when probing over the GRHV outputs and I had music.

I replaced everything back to C2M1000170D and all was stable. To be honest I haven’t done enough testing to know whether the GRHV with the C3M0350120D would be ok in the field or not. But hopefully you can gain some insight from my experience with it.

 

Some similar experiences here,but microchip MSC750SMA170B instead.

Was using it on my GRHVs, same issue when PSU was measuring normal under no load (both rail measured around 401V),but dropping to about -180V on B- and B+ also seems a bit off (about 391V) as powering carbon amp which is using now precious C2M100070D.

Everything back to normal as I swapped microchip SiCs back to C2Ms...

but I would continue trying any alternative option on GRHV.

 

Edited by ang728
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  • 2 months later...

Tried GeneSic G2R1000MT17D to power BH with no luck,

showing similar behavior  johnwmclean mentioned,negative rail will drop significantly and came back to about 395V after some random voltage probing.

 

not sure if raise up the 5pf cap value would help

Edited by ang728
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  • 1 month later...

About to (finally) begin testing the pair of GRHVs (and a Carbon) I built. Do I need any sort of load for testing the power supplies? I seem to recall seeing Kevin recommend a 16ohm x W load resistor.

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all the golden reference I have built (both low and high voltage) produce the expected output with no load. (unlike some 78 or 79 series voltage regulators)

if you build the smd versions of the golden e.g. the gr78xx they are not stable until you have output caps as well.

16R load is way way to low resistance for anything except fireworks/smoke....

 

to make the maths easy say the HV is 160V and 16R. V/R = I so thats 160V/16R = 10A... NO way a GR hv is going to provide that and if it could....

power = I * V = 10A * 160V = 1600W..... or 1.6KW...

thats going to be one BIG load resistor....

the figures will be worse with even higher voltages e.g. 450V

1.6K resistor would give you 160V/1600R = 0.1A and 16W which is still a fairly big resistor at 160V output.... 16K seems more reasonable for higher voltages than that....

 

for the gr lv, assuming 16V output and the same 16ohm resistor, you would still pull 1A and get 16W...

and worse at higher voltages....

For testing the LV I use a electronic DC load

I never power up newly built power supplies without using a variac to give me at least some indication of issues at lower voltages.

you could temporarily put a resistor in parallel over the voltage setting resistor(s) to reduce the output voltage to more "safe levels" e.g. say 50V output on the grhv. (variac recommended to you don't get too much voltage drop and therefore heat in the pre regulation stages and across the pass mosfet).

 

 

 

Edited by jamesmking
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Thanks James (and John). I was going to go thru the checks that soren laid out in the circlotron thread (and I copied his post earlier in this thread), and then power them up on a variac, unloaded. It might have been a 16K resistor that Kevin had mentioned, but I never bought any load resistors for doing this. Unfortunately my variac doesn't have an ammeter in it, but I'll just take it slow. I also don't have a dim bulb tester, but if needed, might build one.

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If you want to test at full load for the Carbon, it would be around 6K at the full 450V.  I would parallel at least two resistors and mount them on a nice big heat sink...

Here's a test load I use for the T2 supplies.  

20220319_203000156_iOS.thumb.jpg.12a101a0efb268d43ba8bdb95f217e73.jpg

Even with a very large heatsink it will get hot pretty fast.  You can certainly test with less current (recommended), which should expose any issues with the power supply.  

Also, I agree with James on testing first with low voltage.  I typically do 30V - 60V on the input of the HV supply and then put a temporary resistor across the set string (excluding the first 20K or 14K resistor - depending on the vref used).  This way you know the power supply is regulating (figure on about 15V - 20V of dropout in order to regulate).  After that, it's unlikely that there will be any issues.

Good luck :) 

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OK, ran thru this on both boards:

Initial check:

  1. The CCS's
    Use a lab supply at some ~15-20V, through a DMM at mA: put the (+) at the drain (middle leg) of the 10m90, and the (-) at the bottom of the CSS where R2(100) and R1(4k5) meets ...you should get ~2mA ....if you see much more, try replace the DN2540.
    Do the same at the other CSS: (+) to drain (middle leg) at the 10m90, and (-) at the bottom (pin 6 at the voltage reference) ...you should get ~1.3mA ...if not the 10m90 is probably damaged. 
    Check the current limiting CSS you added (your drawing) the same way (Kevin suggested 50mA for this)

 

For the first test, I was getting 1.6-1.7mA for both boards. 2nd test I was getting -1.3mA with the red lead on the 10m90 and black on lt1021 pin 6. I guess I will assume everything good so far...

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Sounds good. 

For the first test (10M90S / DN2540), I run these with a little less current these days (you don't need to).  I don't have the schematic for this board in front of me, but I thought the set resistor for this was around 3K.  Is that R1?

On the second test, you could also put the (-) on ground and then check the voltage at pin 6 of the reference from ground to pin 6.  As long as the voltage reference is in the right orientation and functioning, this will work.  I don't do this test unless it's not regulating (low voltage test above).  That being said, if the reference is in backwards, things will pop.

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Posted (edited)

R1 is 4.7K (Soren said 4.5K in his text).

Regarding the low voltage test, for the GRHV, the gain is calculated similarly to the GRLV? i.e., ((Ra / Rb) + 1) * Vref, so for this one set for 400V, it would be (((390K + 390K) / 20K) + 1) * 10, or 40 * 10? If I did something like parallel one of the 390K with 1K, I would get ~205V. Using an Antek AS-3T325, the GRHV should regulate at about 75Vac input (325/115 turns ratio)? Just making sure I'm understanding the concept. Or would you go even lower for this test? James recommended ~50V output for this.

EDIT: If I parallel 100K across the 2x390K that would give me about 55V output. I'll probably do that instead.

 

goldenreferencehvsic.PDF

Edited by Pars
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  • 2 months later...
  • 2 months later...
34 minutes ago, BadgerMcBadger said:

does anybody knows what this is? i found it in the schematics google drive under the name goldenreference2image.png.bd4a36abdce1db1119a8a71b81e90efc.png

Looks like the GRLV v.44/.45, why?

One of the best low voltage power supplies. It has its own thread, btw, link here.

Edited by audiostar
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