TRX1 DDS Board

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TRX1 DDS Board

Postby WB2MSC » 23 Nov 2012 17:45

Matti and others,

Well, I was defeated by that small DDS IC1 chip. I tried to solder it but it was so tiny that I got solder bridges and finally lifted a pad or two. I couldn't get my iron onto any one pad. How do the experts handle this?

I assume the board is useless and will have to order a new one. I looked at it under a microscope and it looked bad.

Is it possible to order a new board and have that chip soldered on for me (at extra cost)? I would need the entire board and parts with the exception of the actual display unit which was not involved in my mishap.

What can be done here?

Thanks

Marc WB2MSC
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Re: TRX1 DDS Board

Postby AA4PB » 24 Nov 2012 18:21

I lifted a run while replacing the RS232 chip. I used a strand from a piece of stranded wire to make a jumper between the IC pin and the nearest via from the original run. If you look closely you can usually find a nearby connection that you can solder to.

For this type of work you really need a temperature controlled soldering station an a really small tip that will fit on one IC pin at a time.

73,
Bob
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Re: TRX1 DDS Board

Postby WB2MSC » 24 Nov 2012 20:59

Hey Bob

It's great to meet you.

I did what you suggested some time ago on another project with more substantial traces and pads. The pads for this part are so small. But, I think I will take your advice and try it here. I suppose I can also go from the nearest component as well. I have a digital Weller station with a conical tip. I will look and see if there is an even sharper tip. Matti and Juha suggested in the literature that the pads should be tinned all the way around and then soldered using what is on the pad. Is that how you do it?

If I order another part, does it have to be programmed? It is a programmable part. If it does, I guess I should order that from Finland instead of just buying one through Avnet.

Bob, thanks for the input.

73, Marc WB2MSC (Central New Jersey)
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Re: TRX1 DDS Board

Postby AA4PB » 28 Nov 2012 00:59

A new part will have no boot loader programmed into it. You can load the progam after the radio is completed IF you have the necessary programmer. The easiest way is probably to get the part pre-programmed from Juma. Once the radio is finished and working you can upgrade the firmware from a PC if desired, using the bootloader firmware that is programmed into the IC.

You'll find some info about firmware upgrades and the boot loader on the Juma web page.

I only tinned one of the leads and put flux on all the others. Then I tacked the IC in place with the tinned pin and then soldered each of the others. I had problems with my board being tarnished and giving problems with taking solder. I used a pencil eraser to clean the contacts before trying to place the part. The little 3-pin diodes and FETs gave me the most difficulty because the PC contact size is so small.

Be careful for correct orientation of the 232 serial port chip. Mine had no pin-1 marking. I downloaded the mfg spec sheet and drawing which showed one edge had a sharper angle taper that the other. You can see the difference if you look directly at the end with a magnifying glass.
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Re: TRX1 DDS Board

Postby WB2MSC » 28 Nov 2012 12:09

Thanks again, Bob

I had no trouble with the 3 pinners. Just so long as there is room for the iron, I'm alright (if I dig my elbows into my side and rest the palms on the table). I do what you do for the larger chips, exactly. But, that little monster DDS. I ordered a long conical 1/64 tip. It was the sharpest they had. I was looking around on the web on they even make MSOP to DIN adapters. You still have to solder the DDS to it though.

I followed your lead and checked the continuity on all the pads. One was lifted so I scraped a small bit of insulation off of the trace. The other pads are ok but a few are loose. I was even thinking of getting one of those adapters (about 10 bucks) and hard wiring it to each trace using thin wire. It won't look too good but it might work.

I'll have to do a bit of research on a programmer.

Thanks for all the help.

Marc WB2MSC
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Re: TRX1 DDS Board

Postby WB2MSC » 28 Nov 2012 16:28

Bob and others

I browsed around on the Web for information on programming the AS9833. I am confused (my normal state).

What do I need to program this IC? I already downloaded the C program from the TRX1 page. What programmer do I need?

Thanks

Marc WB2MSC
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Re: TRX1 DDS Board

Postby AA4PB » 28 Nov 2012 17:38

You'll need the Microchip MPLAB ICD2 or ICD3 programmer (the ICD3 is the current version from Microchip). You can do on-board programming with it. There is a programming header on the DDS board. You can probably find some information on the TRX2a main page under technical kit information. It may take some digging to find what you want. I'd recommend that you get the ICD3 kit from Microchip rather than one of the "knock-offs" found on eBay.

Basically you need to get the full hex firmware file that includes the operating firmware and the boot loader firmware and load that into the processor.
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Re: TRX1 DDS Board

Postby WB2MSC » 28 Nov 2012 18:56

Hey Bob

I looked up the MPLAB ICD3 online. Not bad.... it is about 189.00 at the usual parts emporiums.

The TRX1 DDS board is different from the TRX2A. On the TRX1 board I see a line of 6 pads that just have a little solder on them. Am I correct in assuming that this is for the programming interface? I guess I would need some sort of header there. I would also need some type of interface between that header and the RG11 of the prommer.

The whole things looks a bit daunting but it's something else to learn.

Thanks again,

Marc
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Re: TRX1 DDS Board

Postby WB2MSC » 29 Nov 2012 01:06

Bob forget the last post...those pads are for wiring...duh! Marc
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Re: TRX1 DDS Board

Postby WB2MSC » 30 Nov 2012 09:37

Well, I tried another AD9833 and failed again.

My last attempt - I got one of those MSOP to DIP adapters and will wire it to various places on the DDS board according to the schematic. It will be necessary to try the rework station for the first time as I will never be able to solder that IC to the adapter.

Does anyone know what the proper temperature setting of the heat gun should be? I will be using chip quik solder paste 63/37 leaded. Any advice as too how long I should apply heat so as not to cook the final, remaining AD9833?

Does anyone have a TRX1 DDS board laying around they would like to sell?

Perhaps JUMA could sell me a new board with all the parts, preferably with the AD9833 already mounted? I sent an email to Arno but haven't heard back. This unit and others are being ramped down.

Thanks, Marc WB2MSC
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