Great River MP-2 , info, schematics & discussions

[G-Sun]

I'm a little confused about the pin-numbering for the molex-connectors.
The Molexs has a number 1 marking, reading right to left when looking at the pcb (Left to right when looking at the connector itself)
Yet looking at the schemo, the numbering seems like, left to right, and this is also what I would expect. This is for J1-J6.
But when it comes to J7 and J8 the label is vertical to the pins.
Meassuring J7, looking from front og unit, the numbering seems right to left.
J5 is shorted 2-3, so measured that, and yes, left to right.

Seems like I've been doing it right

 

[G-Sun]

Peak led driver:
Where do I connect the negative pin here?

 

[okgb]

The great rivers led comparator  / peak  circuit is situated on the P.S.U. pcb

 

[dmp]

I had to knock one of these old beast's off this week for a buddy, thought you might
get a kick out of one built from "scroungin's"

Anyone know where to get those mounting clips for the input transformers? Probably a capacitor mount but I haven't been able to find one like it - to fit in a 1U case.

 

[G-Sun]

I'm a little unsure about the voltages for the boards.
I have a 14 VA 24-0-24 pwr xfrm for 2 boards, using it with a JLM ACDC.
Mm.. that's not a big enough transformer, is it?

Edit: Found this:
http://groupdiy.com/index.php?topic=20333.msg466906#msg466906

 

[G-Sun]

Both white and black should go to a ground, chassis is best.

Thanks!
Yes, I see ground scheme in post#1 now.
I've connected input xfmr black/white to pcb pins. hmm. Not the best is it?

The great rivers led comparator  / peak  circuit is situated on the P.S.U. pcb

Thanks. Ok, I use a JML ACDC..
So, is J11  the power led?
But peak led is on board pcb J8 pin1. Where do I connect the minus pin?
Is it a pin on psu board J? pin?

Sorry about late reply. Had notifications set to weekly and thought I was far to late to the party

 

[G-Sun]

The great rivers led comparator  / peak  circuit is situated on the P.S.U. pcb

Ok, so a main part of the psu pcb, U1-U4 with caps/resistors are for the drive led?
Hm.. I have led-holes and leds, but not the pcb to feed it. I see..

Some of my questions might seem a little odd for you,
but you see, I bought a stuffed not wired dual project from ericjazz

 

[dmp]

But peak led is on board pcb J8 pin1. Where do I connect the minus pin?
Is it a pin on psu board J? pin?

J8 on Audio card is power. J6-J9 on the supply schem connect to the audio boards. Pin 1 connects to pin1, etc.
pin1: signal for peak led, pin2: V-, pin3: GND, pin4: V+, pin5: Vphantom

Ok, so a main part of the psu pcb, U1-U4 with caps/resistors are for the drive led?
Hm.. I have led-holes and leds, but not the pcb to feed it. I see..

I'm in progress building one and am leaving out the peak LEDs. If you want this function and don't want to build the circuit on the supply schem, you could get a board from JLM audio.

 

[G-Sun]

J8 on Audio card is power. J6-J9 on the supply schem connect to the audio boards. Pin 1 connects to pin1, etc.
pin1: signal for peak led, pin2: V-, pin3: GND, pin4: V+, pin5: Vphantom

I'm in progress building one and am leaving out the peak LEDs. If you want this function and don't want to build the circuit on the supply schem, you could get a board from JLM audio.

Thank you!
Yes, I see the JLM-kits

now, how important is the peak-led to me? Well, I guess not so important.
Thanks for the clarifications!

 

[okgb]

The original mp-2 uses a Comparitor type circuit which looks at both the positive & negative cycles of the waveform
it is effective offering a softer glow as it comes up to the peak level. Having said that I seldom see mine [ a quad version ]
light as I watch the recorder levels , so I'd think you can be totally fine without it . It's worth the effort but not necessary . 

 

[G-Sun]

I need to make calculations for my power-led
I guess it's about as basic at it can get, but I'll take it here as I'm not to experienced.

I have a led (green, 4mm bulb) with unknown ratings
(I know I should order one myself, but I forgot, and I have this one.)
From Farnell, the only led available for green/4mm is 20ma/ 2,2V or 3V.
So, I'll calculate with 20ma/2,2V  (that's the safe side isn't it?)

So I need to find the correct resistor for wiring 24Vdc from my psu

Formulas
V = RI  >>  R = V/I

for series resistors
V = (R1+R2)*I  >>  R1 = V/I -R2

Resistance in led (R2):
R2 = V/I = 2,2V/0,002A = 1100ohm

New resistor (R1)
R1 = V/I-R2 = 24V/0,002A - 1100ohm = 10k9ohm

Watt rating needed for R1 is:
W1 = A^2 * ohm = 0,002A^2 * 10900ohm = 0,0436W = 43,6mW

So, I need a resistor min. 10k9ohm/44mW.
Is this correct?

 

[Harpo]

From Farnell, the only led available for green/4mm is 20ma/ 2,2V or 3V.

http://de.farnell.com/cree/c4smf-gjs-cv00792/led-4mm-oval/dp/1855559
http://de.farnell.com/avago-technologies/hlmp-lm75-34cdd/led-4mm-ingan-40x100deg-gruen/dp/1897161
http://de.farnell.com/kingbright/l-1413gdt/led-4mm-flachkopf-grun/dp/1142531
for uncommon diameter 4mm thru hole green LEDs from Farnell.
LEDs forward voltage varies in range 2.2V ... 4.0V.
For your unknown green LED calculate for the worst 2.2V and probably less than parts max.forward current 20mA, maybe 10mA to not build a headlight. Use lesser current for lesser brightness and vice versa and don't exceed parts limits.

So I need to find the correct resistor for wiring 24Vdc from my psu
Formulas
V = RI  >>  R = V/I

for series resistors
V = (R1+R2)*I  >>  R1 = V/I -R2

Resistance in led (R2):
R2 = V/I = 2,2V/0,002A = 1100ohm

New resistor (R1)
R1 = V/I-R2 = 24V/0,002A - 1100ohm = 10k9ohm

Watt rating needed for R1 is:
W1 = A^2 * ohm = 0,002A^2 * 10900ohm = 0,0436W = 43,6mW

So, I need a resistor min. 10k9ohm/44mW.
Is this correct?

You calculated for 2mA.
Maybe easier approach is
[(supply voltage - LEDs forward voltage) / LEDs forward current that you allow for = current limiting resistor value needed,
FI (24V-2.2V)/0.01A=2180 ohm.
This 2K2 resistor will dissipate 0.01A^2*2200 ohm=0.22W, so doubling up the wattage, a 0.5W rated resistor will run way cooler and not self unsolder.

 

[dmp]

I almost always use a resistor more like 10k ohms, since I don't like them very bright. If you run the LED at 20 or even 10 mA, I think it is going to be very piercing.

Resistance in led (R2):
R2 = V/I = 2,2V/0,002A = 1100ohm

This is a little bit off - a LED doesn't have a 'resistance' it has a voltage drop.
Better to write the equation:

R = (V_24v - V_led)/I

 

[G-Sun]

LEDs forward voltage varies in range 2.2V ... 4.0V.
For your unknown green LED calculate for the worst 2.2V and probably less than parts max.forward current 20mA, maybe 10mA to not build a headlight. Use lesser current for lesser brightness and vice versa and don't exceed parts limits.

So I need to find the correct resistor for wiring 24Vdc from my psu
Formulas
V = RI  >>  R = V/I

for series resistors
V = (R1+R2)*I  >>  R1 = V/I -R2

Resistance in led (R2):
R2 = V/I = 2,2V/0,002A = 1100ohm

New resistor (R1)
R1 = V/I-R2 = 24V/0,002A - 1100ohm = 10k9ohm

Watt rating needed for R1 is:
W1 = A^2 * ohm = 0,002A^2 * 10900ohm = 0,0436W = 43,6mW

So, I need a resistor min. 10k9ohm/44mW.
Is this correct?

You calculated for 2mA.
Maybe easier approach is
[(supply voltage - LEDs forward voltage) / LEDs forward current that you allow for = current limiting resistor value needed,
FI (24V-2.2V)/0.01A=2180 ohm.
This 2K2 resistor will dissipate 0.01A^2*2200 ohm=0.22W, so doubling up the wattage, a 0.5W rated resistor will run way cooler and not self unsolder.

Thanks a lot!
That's really helpful of you. Yes, I see my mistake now And thanks for the non-headlight-suggestion!

I don't have a 2k2/0,5W, but I have some 1k and 3k8 in 1/4W. I need it 1/2W? Ok, then 2 in series or paralell is ok I guess?

Is it ok put heatscrink around the resistors (I'll just wire-res-res-led), or is that bad for heat-buildup?

 

[G-Sun]

I almost always use a resistor more like 10k ohms, since I don't like them very bright. If you run the LED at 20 or even 10 mA, I think it is going to be very piercing.

Resistance in led (R2):
R2 = V/I = 2,2V/0,002A = 1100ohm

This is a little bit off - a LED doesn't have a 'resistance' it has a voltage drop.
Better to write the equation:

R = (V_24v - V_led)/I

Thanks for the education and advice. Appreciated
If I go higher in resistance I can use 1/4W I guess. I'll see what I have.

 

[Harpo]

And thanks for the non-headlight-suggestion!
I don't have a 2k2/0,5W, but I have some 1k and 3k8 in 1/4W. I need it 1/2W? Ok, then 2 in series or paralell is ok I guess?
Is it ok put heatscrink around the resistors (I'll just wire-res-res-led), or is that bad for heat-buildup?

For previously posted Farnell links to 4mm green LEDs, brightness for same forward current between 1st. and 3rd. link are factor 1333 apart on paper (4cd vs. 3mcd), maybe only typo. Your unknown type of LEDs brightness and viewing angle might be somewhere in between.
I'd try two of your 3K8? (probably 3K9) in parallel for 1K95, allowing worst case 11.2mA If if your unknown type would be 2.2 Vf and maybe tweak for eye pleasing result before heatshrinking.

 

[G-Sun]

And thanks for the non-headlight-suggestion!
I don't have a 2k2/0,5W, but I have some 1k and 3k8 in 1/4W. I need it 1/2W? Ok, then 2 in series or paralell is ok I guess?
Is it ok put heatscrink around the resistors (I'll just wire-res-res-led), or is that bad for heat-buildup?

For previously posted Farnell links to 4mm green LEDs, brightness for same forward current between 1st. and 3rd. link are factor 1333 apart on paper (4cd vs. 3mcd), maybe only typo. Your unknown type of LEDs brightness and viewing angle might be somewhere in between.
I'd try two of your 3K8? (probably 3K9) in parallel for 1K95, allowing worst case 11.2mA If if your unknown type would be 2.2 Vf and maybe tweak for eye pleasing result before heatshrinking.

Yes, thanks. I'll maybe try something 6k8 x2 in parallel first following dmps advice.

 

[tonedude]

Hi, I'm about to build a stereo pair of these and wonder if I it's possible to use a pair of LL1524 (http://www.lundahl.se/pdf/1524.pdf) as output transformers in the MP2? Another alternative I thought of was to use a pair of That 1646 as line drivers (or is this not necessary when omitting use of output transformer...???). Mic input transformers will be the LL1538XL.

- What do you think about using the LL1524 as output transformers in this circuit?

thx, mattias

 

[dmp]

Any 1:1 output transformer will work for the output. The 1524 doesn't match the specs of the JT-11BM, but that might be fine.
You can also just run an unbalanced out.

 

[tonedude]

Ok thanx, I'll try out the alternatives above to see how I like them.

/ Mattias