Si570 Install Question

General discussion and support for the Peaberry SDR V2.

Si570 Install Question

Postby KC5SB » Sat Jul 20, 2013 4:04 pm

Hello all – I’m new to the forum. I am enjoying building my Peaberry V2, but have hit a snag. Maybe someone can advise me. I am experienced at building stuff – have been a ham for many years (over 50) and have successfully built and used a Softrock Ensemble RXTX so am familiar with SMD construction.

All was going well in the Peaberry V2 build until I installed the Si570. After the install the LED is still blinking I2C. I noticed that the current draw on the previous step (24 MHZ Crystal) was around 49 ma, not the specified 55 – 65 ma. Current draw after the Si570 install was 120 ma, not the 130-150 in the instructions.

I did not solder the pads on the narrow sides of the Si570 per the instructions. However, I did notice that they are making contact with the trace pads on the PCB. Could this be a problem?

Careful examination with a 10x eye loupe does not reveal any obvious solder bridges. Suggestions and comments would be appreciated.

Thanks,

Bill KC5SB
KC5SB
 
Posts: 49
Joined: Sat Jul 20, 2013 3:41 pm

Re: Si570 Install Question

Postby AE9RB » Sat Jul 20, 2013 4:26 pm

The extra pads will not make contact with the PCB. It is physically impossible.

If you're still blinking I2C then you have made a soldering error on any of U9 pins 7+8, R48, R49, or U11 pins 10+11 (the I2C bus). Keep looking. Get a friend to look. Post photos.
73 David AE9RB
AE9RB
Site Admin
 
Posts: 511
Joined: Thu Nov 15, 2012 5:27 am
Location: Portland, Oregon, USA (CN85ql)

Re: Si570 Install Question

Postby KC5SB » Sat Jul 20, 2013 5:22 pm

Thanks for the quick reply David. Unfortunately things have gone from bad to worse. After re-doing the soldering on the PSOC the LED is not blinking at all. R1 gets VERY hot and tries to release smoke before removing power. I have not had time to look at the schematic, and will probably not be able to get back on this project until tomorrow sometime. I may have shorted some pins on the PSOC while I was trying to 'fix' my soldering. Suggestions appreciated!

73,

Bill KC5SB
KC5SB
 
Posts: 49
Joined: Sat Jul 20, 2013 3:41 pm

Re: Si570 Install Question

Postby AE9RB » Sat Jul 20, 2013 9:53 pm

Yep, it's what you think... a solder bridge.
73 David AE9RB
AE9RB
Site Admin
 
Posts: 511
Joined: Thu Nov 15, 2012 5:27 am
Location: Portland, Oregon, USA (CN85ql)

Re: Si570 Install Question

Postby ns7eart » Sun Jul 21, 2013 1:18 pm

I did the same thing and got a SI570 fail .
looking at all the pictures and schematic the small sides are soldered but be carfull that you only solder it to the center
of the three brass dots on the narrow ends .
I did this and now solid light green
Arthur NS7E
ns7eart
 
Posts: 24
Joined: Thu Jul 18, 2013 3:52 am

Re: Si570 Install Question

Postby KC5SB » Sun Jul 21, 2013 11:58 pm

Thanks for the replies. Thought I would bring you up to date on my adventure in building the Peaberry V2. A process of elimination revealed that the short was in the +5V(B) circuit. As suspected, there were solder bridges in the PSoC. I was trying to take a shortcut when mounting the PSoC by soldering multiple pins at once and soaking up the bridges with solder wick. For anyone else thinking of trying this, please know this is a very bad idea. Solder worked its way behind the pins of the PSoC and was impossible to remove with solder wicking.

After some reflection, I concluded that the only solution was to remove the the PSoC and start over. This is a pretty daunting task, especially if you don’t have the proper equipment, which I don’t. But it was the only way out that I could see. First, I removed any surrounding components and then slowly worked a long straight dental pick behind one side of the U11 pins while heating a few pins at once. If you are very careful you can eventually get the thing loose. Even being very careful, I managed to lift two of the PCB pads (18 and 29). After U11 was out, I used solder wick to clean up the PSoC and the PCB as much as possible. I used a straightedge on a flat surface to carefully straighten the U11 pins back into shape. I had to use a lot of magnification during this process. This is very far down my list of things that I ever want to do again.

Since the PCB pad was missing from pin 18 I made a jumper from the LED to pins 18 and 19 on U11 (they are connected per the schematic). I decided not to worry about pin 29 at this time since the schematic shows it going to pin 8 of the debug header. I can add that later if I need to.

After carefully resoldering U11 and restoring all the previously removed components the LED flashed I2C – back to where I started! Whew!

Now, after reading the post from NS7E I realized that I had misread the instructions. I had not soldered the pads on the narrow sides of the Si570. After doing that the LED is happily flashing PCM3060 and the board is pulling about 120 ma.

I will get the scope out later this week and check for a square wave per the instructions.

Here is a question – after installing the crystal the board is only pulling 49 ma rather than the 55-65 per the instructions. Also after installing U14 the board is only pulling 120 ma rather than the 130-150 per instructions. Is this a problem that I should look into?

Sorry for the long post, but I figured this info might help someone else.

Bill KC5SB
KC5SB
 
Posts: 49
Joined: Sat Jul 20, 2013 3:41 pm

Re: Si570 Install Question

Postby AE9RB » Mon Jul 22, 2013 12:49 am

You must use extra solder flux on the ICs. This isn't optional. If you rely on only what's in the core of your solder then you will have the problems you describe.

Current is not a valid way to test this design but lots of folks think it is and wanted the measurements. I put what I measured in the manual but, as predicted, they are not matching devices in the field. I will update the manual to steer folks away from using them.
73 David AE9RB
AE9RB
Site Admin
 
Posts: 511
Joined: Thu Nov 15, 2012 5:27 am
Location: Portland, Oregon, USA (CN85ql)

Re: Si570 Install Question

Postby ns7eart » Mon Jul 22, 2013 2:11 am

I used the testing reading the current as I progressed and thought it was great !
my readings were off a bit at times but not to worry if there was trouble it would
have shown a big difference not just a few ma's .
Arthur NS7E

and on the ic instillation I used a trick I learned on building other kits you tin the pads first leaving a thin layer only,
removing almost all with the iron or solder sucker and then tack one corner first , pin one is what I use , then the last pin of that chip
making sure all lines up now I hit each pin with a barely wet iron adding a little solder to the iron after say 5 pins or so .
to test and see if you have a good connection with fine point tweezers see if pins don't move your in business.
this worked the best on the SI 570 I tinned both chip and PCB pads then used sucker to remove any bumps and then just heat with iron .

I had to use all 8 pads on the chip in order to get the si570 alarm to clear without the small ends soldered it could not see the si570 chip?
I see all the discussion about not using the ones on the smaller sides ???? did not work for me!
Arthur NS7E
ns7eart
 
Posts: 24
Joined: Thu Jul 18, 2013 3:52 am


Return to Peaberry SDR V2

Who is online

Users browsing this forum: Bing [Bot] and 1 guest

cron