SSR02 fixed voltage, fine adjustement and DZ1 Qs

[Malefoda]

Hi there,

having built +5 & -5 LT1028ACN & LM431 based SSR01 & SSR02. They all show a rock solid +/-4.98V, can't see lower on my DMM.

Now with a -15V.
Same, R12 being 499 in all SSR0x, but the DZ1 wich is a yellow Led. All starts fine with an -14.83V.

• this yellow Led is always on, isn't it supposed to go off after a while?
• what R to change in order to get -15V or better -14.98?

Regards,

Matthieu

[peranders]

The LED should be lit. This is a sign that you have a constant voltage across R4 and the regulator is regulating.

If you are using opamps it doesn't matter if you have 14.67, 14.83 or even 15.17 V as long it's stable. Around VR1 you have empty places for addition resistors. You can also tweak the gain a bit. Also there you have extra resistor locations. If you feel that this is important for you and you are not able to calculate yourself I can help you with this. For this I want to know used resistor values and also the reference voltage, measured directly over the LM431.

[Malefoda]

Hi Per-Anders,

yes I need as close as -14,98V
Right I have all R values like in your files for download but R12 to 499R, spare parts from my first SSR01 ;)
In the building instruction it's 470R, is this one of the trick?

If changing some R values, a // mix of R to make the right one is welcome.

I have -4.84V at the first pin of the LM431.

Side question, about the -5V one, I've found the LM337 to run warm without any load, maybe because of the same -25V as the -15 SSR02? Voltage drop story?
Even if my DMM shows a stable -4.98V... I've checked LM431 and it shows 0V at that first pin but -2.49V at the second one, same 2.4 as the +5 but the first pin! Maybe no problem here it's just me getting nervous at a fly passing by ;) The SSR01 at +5 is powered by +11V and stay barely warm.

Thanks,
Matthieu

[peranders]

Have you really used my BOM for -15V? The LM431 should have 7.50 V at the cathode. The gain should be 2 and you seems to have 3.

To see that everything is working OK. The LM431 should have 2.50 V +- 2% between ground (anode) and ref.

The regulator consumes some power so 5 V out and 25 V in will create some power losses and most of if is in the LM337. LT1028 is rather thirsty too.

Curious, but what is your need for 14.98V? (15V within 1.3‰)

[Malefoda]

Hi,
yes I've done it according to your BOM, but as I'm a bit "mindless" it's still possible that I've mixed parts or missed one
I have 4.84V between pin 2 & Grnd,
7.31 between pin 3 & Grnd,
0 at pin 1 & Grnd.
2.472V betwenn pins 2 & 3

The computer is away from the stuff so I can't keep in mind what pin is what in wich order :'(

The Reg is for a TDA1541A S1 wich perfom best with a nice -10V between its negative rails. I also like to "cut the hair in quarters" or "fuck the flies" (sorry french sayings to express someone very boring finding problems where there are none ;) ).

Thanks!
Matthieu

(defo a pretty kitty)

[peranders]

If you can tell me which resistor values you have I can calculate how to get near -15 V.

[Malefoda]

Hi,
you mean the real ones, not the BOM ones?
100% BOM ones but R12 a 499R.
I'll get the precise values this noon.

Edit:
here what I have on the board, close ones showing the same are in // I suppose,
R1 0.996K
R2 0.996K
R3 2.195K
R4 100R
R6 47.05R
R8 944R
R10 925R
R11 925R
R12 499R
R13 1.952K
R14 4.79K
R16 3.743K
R17 3.743K

Voilà !

[peranders]

A fast calculation shows that something is wrong here. Have you measured on soldered resistors?

Have you checked my BOM and compared?

[Malefoda]

A fast calculation shows that something is wrong here. Have you measured on soldered resistors?

Yes, I know that's a bit stupid...

Have you checked my BOM and compared?

Yes, both pics (15 based but all R the same) & list

[peranders]

Can you tell me the values of the resistors, and of course the value which they are marked with?

I have a very good picture of the 15V, LM431 positive version which is exactly the same as the SSR02 when it comes to resistors.

http://sjostromaudio.com/hifi_pics/hifi_100pr/ssr01r0_15V_LM431.jpg

[Malefoda]

It's the exact copy of this picture but R12 and values are:
R1, R2, R8, R11   1k0
R3, R13   2k2
R4   100R
R6, R9   47R
R7   0R0
R10   39k
R12   499R
R14   10k
R16   5k6
R17   56k
R18, R19   nothing
J1, J2   Tin jumper

[Malefoda]

I've checked again, it's really like this.
Hope I can make that adjustment, telle me if more tests are needed.

Matthieu

[peranders]

Check my Excel file.

[Malefoda]

Ok that means I'll have to remove the R and check them.
I'll report my findings.

[peranders]

If you have 1% resistors you can consider them as "exact". Just change the ones who are different.