JSR03 troubleshooting

[h3ndrix]

heaveno again,

I am trying to build two JSR03 modules purchased from the Sjöström shop, one for 9V and one for 5V for a CD player that is outlined at this site:

Bergrans CD Player http://www.bergrans.com/site/cd-pro2mlf-cd-player/power-supply/

Using the components he suggests here:

Components for 9V and 5V http://www.bergrans.com/cd-pro/doc/component_list_JSR03.pdf

Unfortunately I am geting weird results:

1. In the 9V module, I am getting a constant cycle beginning from 9.6V to 12.2V. The regulator starts at 9.6V and slowly rises to 12.2V and then suddenly drops back to 9.6V. Weird.

2. In the 5V, I am getting 16V (the input is 17.6V) and the LT1086 does not seem to be working.

I tried to simulate this design using LTspice but, its not working. My simulation in LTspice does not seem to give the correct results no matter what I do. Where am I making a mistake? The attachment has the files I used for simulation, please check.

What am I doing wrong here?

Thanks.

P.S. here is the AD825 spice file I am using.

Code Select Expand

* AD825  SPICE Macro-model
* Description: Amplifier
* Generic Desc: 50MHz FET input op amp
* Developed by: JCH / ADI Cent Apps
* Revision History: 08/10/2012 - Updated to new header style
* 1.0 (10/1999)
* Copyright 1999, 2012 by Analog Devices, Inc.
*
* Refer to http://www.analog.com/Analog_Root/static/techSupport/designTools/spiceModels/license/spice_general.html for License Statement.  Use of this model
* indicates your acceptance with the terms and provisions in the License Statement.
*
* BEGIN Notes:
*
* Not Modeled:
*
* Parameters modeled include:
*
* END Notes
*
* Node assignments
*                non-inverting input
*                | inverting input
*                | | positive supply
*                | | |  negative supply
*                | | |  |  output
*                | | |  |  |
.SUBCKT AD825    1 2 3 4 5
*
* INPUT STAGE & POLE AT 245 MHZ
*
R3   5  50   1084.2
R4   6  50   1084.2
C2   5   6   0.3E-12
I1   99  4   1.0E-3
J1   5   2   4   JX
J2   6   3   4   JX
Cin  1   0   3E-12
Ios  1   2   15p
Vos  1   3   1mV
*
EREF1 98 97  99 0 0.5
EREF2 97  0  50 0 0.5
*
* GAIN STAGE & POLE AT 1.92 KHZ -- GAIN REDUCED SLIGHTLY TO MATCH SLEW RATE
*
R5   9  98   6.9E6
C3   9  98   4.5p
G1   98  9   5  6  4.9E-4
V2   99  8   6.1
V3   10 50   6.05
D1   9   8   DX
D2   10  9   DX
*
* POLE AT 200 MHZ -- GAIN ADDED TO MAKE UP FOR REDUCED GAIN IN PREVIOUS STAGE
*
R9   23 98   1E6
C8   23 98   0.8E-15
G5   98 23   9 98 1.86E-6
*
* OUTPUT STAGE
*
R15  29 40   16
R16  29 41   16
L1   29 31   6E-12
V6   31 30   0
G7   29 40   99 23  6.25E-2
G8   41 29   23 50  6.25E-2
V4   25 29   1.4
V5   29 26   1.4
D3   23 25   DX
D4   26 23   DX
Vt1  99 40   0
Vt2  41 50   0
*
*SUPPLY CURRENT CORRECTION
*
ISY  99 50 5.5m

Fo1   98 110 V6 1
Do1  110 111 dx
Do2  112 110 dx
Vi1  111  98 0
Vi2   98 112 0

Fsy1   0 99 Vt1  1
Fsy2  99  0 Vi1  1
Fsy3  50  0 Vt2 1
Fsy4   0 50 Vi2 1
*
* MODELS USED
*
.MODEL JX PJF(BETA=4.25E-4  VTO=-2.000  IS=5E-12)
.MODEL DX   D(IS=1E-15)
.ENDS
[attachment deleted by admin]

[peranders]

I'll recommend that you take a look at my BOM for 5 and 9 V. I take no responsibility for others work concerning component choices.

Something is not correctly mounted.

• have you shorted the sense inputs on the solder side?
• For 9 V, do you have 4.5 V reference voltage?
• 2.5 V for the 5 volt version?

[h3ndrix]

I also made a simulation using your specified components, I still cant get the right results.

The Ltspice files and components are attached below.

[attachment deleted by admin]

[peranders]

If you put the simulation aside and measure I can guide you in the trouble shooting. The design works perfectly if you use my BOM and put everything in the right place. So, can you come back with answers for the three questions above?

[h3ndrix]

Whats wrong with the simulation?

I will try to get the parts, however, I am having a hard time understanding some of the BOM parts for the 5V and 9V, you have some remarks (on the right side of the excel sheet) that are different than what you state on the list (left side of the excel sheet), which one do I use? For example; for the 5Vand 9V BOM, R3, R7, R10, R13 is not clear what the BOM says.

[peranders]

R3, 3k3 but 1k is better
R7, 470R but 510R or 499R is more optimal.
R10, wire
R13, use 2k2

BTW: I misunderstood you. I thought you have build the regulators.

[h3ndrix]

No, no, you read it right. I did make the JSR according to Bergrans, but its either broken or somethings wrong, the photo is attached.

- I did not connect the jumpers
- Where to I measure the reference you mention?

Thanks.

[attachment deleted by admin]

[peranders]

The J1 and J2 must always be connected somewhere. Must not be left unconnected.

I see also that you have R15, R16 unpopulated and that means if you check the schematic that vital parts are floating and unconnected. The reference and the feedback are totally disconnected.

The reference is the IC2, please check the schematics and the pcb layout.

You can measure at one side of the R3.

Could you please take two new photos more from above and one pcb per picture?

C9 should not be mounted.

C12 should not have too low impedance. Can cause instability. "Normal" caps are recommended.

[h3ndrix]

The photos are bigger this time, I cant upload them to the forum, so I am giving links to them below:

JSR 5V https://www.dropbox.com/s/i6iz5tjbs1d97wt/jsr_5V.jpg

JSR 9V https://www.dropbox.com/s/fkbjtv02b0lvw3h/jsr_9V.jpg


A question,

Your BOM specifies the C9 as unmounted, my PCB's have it mounted and you said it should be mounted, what should I do?

[peranders]

Forget the word "not". It says so now. If you have it the regulator will be slower. The cap is for "just in case" of unstablilty.

I do a visual check of your photos.

[peranders]

5V: DZ1 where you have a LED. The cathode must be to the left. I think I see a flat side to the right.

A comment: BC560 and BC860 is the same part but with different package.

[peranders]

9V: Must be some error in the BOM you have used.

R4 = 8k2
R5 = 3k3
R6 = 39k

This will set the reference to 9.24 V. It should be 4.5 V

R4 = 2k4 will correct that.

[h3ndrix]

heaveno!

I got good news and bad news, two good and one bad infact.

- I got the 9V working, I am still using Bergrans components for now, but all I had to do was connect the jumpers. I still havent attached R15, R16, C13 and C14. I will when I get those parts, how important are those for now?

- I got the Spice model working! One problem was AD825 and AD845 models were not working, changed them with LT1028, works fine, get exact results down to 0.1%

Bad news:

- On the 5V model, I am getting a pulsing output. It goes down on voltage every second for about 0.1s and then comes back up. What might be the issue?

Thanks for all your help!

[peranders]

R15, R16 is for in case the sense inputs are unconnected. You see now what happens if not.

Is the LED at DZ1 position lit? Mounted with cathode to the left? Seems to be the opposite.

Do you have a stable 2.5 V at pin 3 of the opamp?

[h3ndrix]

Got the 5V working as well! You were right (as always) just had to switch the DZ1 and it works. Thanks.