It's a good bit of work, but I'm on the home stretch!
Ordered solder paste through work today, should have it in a couple of days. Brought the 3 Pro's into work to hot air rework but had too many other things going on, hopefully I'll get at them tomorrow.
The new solder paste is Chipquik stuff, 20 bucks CAD for a jar versus the 2-3 bucks/jar I've been paying for the cheap Chinese stuff. Guess I'll find out if it's better.
Solder paste arrived today at work, in a bubble wrapped bag with a cold pack. That sure doesn't happen with the Chinese paste 🙂
Ha ha cold pack coming from China! You don't want it to freeze or get too warm for too long in shipping. I keep mine refrigerated and follow the "x hours of warmup to room temp before use" on the datasheet. I like the chipquik syringe format because there is less air exposure vs. the jars. I think I'm about a year past the expiry date and it's still functioning OK, but definitely thicker and a bit trickier to work with. Great shelf life for low volume users like me. Do a test run to make sure your oven profile is suitable for the different formulation!
BK
I'm having a chat with the purchasing guys at work, we're talking about the solder paste I ordered when someone else mentions that the production line just threw out a bunch of expired stuff.
Just raided the chemical disposal cabinet, just got a couple 10ml syringes each of Nordson lead and lead free solder paste. The lead free expired at the end of December, the leaded expired a few days ago.
And even funnier, I ordered 5 jars of the cheap Chinese stuff last night.
Just raided the chemical disposal cabinet, just got a couple 10ml syringes each of Nordson lead and lead free solder paste. The lead free expired at the end of December, the leaded expired a few days ago.
And even funnier, I ordered 5 jars of the cheap Chinese stuff last night.
Managed to get the 3 Pro's reworked, so that's 5/11 of ChuckT's Pro8's done. 6 more Pro8s, a Pro16 and that order's complete!
Pasting four cards now using the Nordson lead paste. Oh man, fresh solder paste is so much better than the last of the Mechanic stuff I used...
Pasting four cards now using the Nordson lead paste. Oh man, fresh solder paste is so much better than the last of the Mechanic stuff I used...
Score! Stored properly, don't worry too much about the expiration date. Even chipquik (forget the actual manufacturer) changed their datasheet recently to say ignore the date if the consistency is still right. Naturally in a production or regulated environment the date must be followed for compliance, but that need not apply to us. 😀
BK
And at 12:40am, reflow is complete on four more Pro's.
The Nordson paste worked much better, but it's got a pretty awful chemical sort of smell to it, especially baking in the oven. I'm using my Weller fume extractor to pull fumes away from the oven when it's going, but it didn't make much of a difference.
I considered trying the RoHS paste but I don't have lead free wire solder or good flux for reworking it.
The Nordson paste worked much better, but it's got a pretty awful chemical sort of smell to it, especially baking in the oven. I'm using my Weller fume extractor to pull fumes away from the oven when it's going, but it didn't make much of a difference.
I considered trying the RoHS paste but I don't have lead free wire solder or good flux for reworking it.
Brought last night's bare Pro's into work to inspect/rework, but was too busy to get that done.
Reflowed four more Pro's tonight, was much more careful stenciling and placing the TPA, and they came out fabulous, no solder bridges on the TPA. Fully assembled them tonight, never got a chance to test 'em. Assuming they work OK, and I can make 3 of the 4 bare cards from last night work, then ChuckT's order is done!
Reflowed four more Pro's tonight, was much more careful stenciling and placing the TPA, and they came out fabulous, no solder bridges on the TPA. Fully assembled them tonight, never got a chance to test 'em. Assuming they work OK, and I can make 3 of the 4 bare cards from last night work, then ChuckT's order is done!
Power supply sizing
I picked up a jar of Kester's lead free stuff and a mini-fridge to store it and other non-beer items for the basement =) I've been happy so far, but it is my first experience doing reflow, so don't have much to compare.
Now onto a Wiener Pro question: Power supply sizing?!
I'm trying to spec out power supply options for a multichannel build, likely consisting of 2 or 3 Pros. I glanced through this thread and the TPA3250 datasheet and it isn't very clear as to the requirements for a power supply. I see in the thread that a 4.5A, 24V SMPS was recommended.
Let's say that I wan't to get the most out of my Wiener Pro while running it in BTL. The datasheet says that I should be able to get "105-W Stereo Peak into 4 Ω in BTL
Configuration at 32 V" at 1% THD. While I of course wouldn't want 1% THD, I am assuming that's a safe max operating condition to build a PSU around.
I'm not sure how to go about figuring out the current required at 32V and 105W output. Does one just apply P=IV here, 105/32 = ~3.3A per channel? I am assuming there is some power losses within the circuit itself so spec'ing a bit above this at 3.5A / channel @ 32V would yield me 105W / channel into 4Ω? Figure 6 of section 7.9 seems to imply that it will continue to approach 100% efficiency as it reaches 100W output.
Additionally, at these operating conditions, will the Wiener Pro be able to dissipate enough heat with its current layout, or should additional sinking be applied to the bottom of the board?
I picked up a jar of Kester's lead free stuff and a mini-fridge to store it and other non-beer items for the basement =) I've been happy so far, but it is my first experience doing reflow, so don't have much to compare.
Now onto a Wiener Pro question: Power supply sizing?!
I'm trying to spec out power supply options for a multichannel build, likely consisting of 2 or 3 Pros. I glanced through this thread and the TPA3250 datasheet and it isn't very clear as to the requirements for a power supply. I see in the thread that a 4.5A, 24V SMPS was recommended.
Let's say that I wan't to get the most out of my Wiener Pro while running it in BTL. The datasheet says that I should be able to get "105-W Stereo Peak into 4 Ω in BTL
Configuration at 32 V" at 1% THD. While I of course wouldn't want 1% THD, I am assuming that's a safe max operating condition to build a PSU around.
I'm not sure how to go about figuring out the current required at 32V and 105W output. Does one just apply P=IV here, 105/32 = ~3.3A per channel? I am assuming there is some power losses within the circuit itself so spec'ing a bit above this at 3.5A / channel @ 32V would yield me 105W / channel into 4Ω? Figure 6 of section 7.9 seems to imply that it will continue to approach 100% efficiency as it reaches 100W output.
Additionally, at these operating conditions, will the Wiener Pro be able to dissipate enough heat with its current layout, or should additional sinking be applied to the bottom of the board?
Re power supply sizing, depends on what you're using the amp for.
If you're using it to drive sine wave tones into things (biamped/triamped with the Wiener doing subwoofer duty with classical music or something, where you can have a loud instrument lasting for upwards of a second) I'd size the power supply for the output power of the amp plus 25%. Say a 4 ohm Wiener driving a 4 ohm load with a 24V power supply, max output power is about 100WRMS across both channels, a 125W power supply will probably be advisable.
Divide those watt numbers by two for an 8 ohm Wiener/load.
If the amp is amplifying full range music with a reasonable crest factor, you don't need much. I'm using a 0-30V/0-1A bench supply to test amps, technically a "25W power supply" I guess. I can trip off the power supply by making my laptop output sine waves, but even with sub-90dB efficiency speakers I can make it uncomfortably loud in the room listening to classic rock or whatever.
For most music listening you don't need a thermal pad. But if you're mounting the amp in a closed enclosure with poor airflow, the thermal pad helps conduct heat out of the card into the case, preventing you from effectively making an oven out of your case. I'd use a thermal pad in this scenario, or use it if you're doing the aforementioned "subwoofer amp" type of scenario.
The card has thermal protection and will shut down before it destroys itself - the Pro will also change its LED color if it gets hot, so you'll know if you've got problems. The thermal pad can be had fairly cheaply from Digikey if you don't get one from me and later find you need it.
If you're using it to drive sine wave tones into things (biamped/triamped with the Wiener doing subwoofer duty with classical music or something, where you can have a loud instrument lasting for upwards of a second) I'd size the power supply for the output power of the amp plus 25%. Say a 4 ohm Wiener driving a 4 ohm load with a 24V power supply, max output power is about 100WRMS across both channels, a 125W power supply will probably be advisable.
Divide those watt numbers by two for an 8 ohm Wiener/load.
If the amp is amplifying full range music with a reasonable crest factor, you don't need much. I'm using a 0-30V/0-1A bench supply to test amps, technically a "25W power supply" I guess. I can trip off the power supply by making my laptop output sine waves, but even with sub-90dB efficiency speakers I can make it uncomfortably loud in the room listening to classic rock or whatever.
For most music listening you don't need a thermal pad. But if you're mounting the amp in a closed enclosure with poor airflow, the thermal pad helps conduct heat out of the card into the case, preventing you from effectively making an oven out of your case. I'd use a thermal pad in this scenario, or use it if you're doing the aforementioned "subwoofer amp" type of scenario.
The card has thermal protection and will shut down before it destroys itself - the Pro will also change its LED color if it gets hot, so you'll know if you've got problems. The thermal pad can be had fairly cheaply from Digikey if you don't get one from me and later find you need it.
State of the nation: every Pro card is now built and tested! Which makes ChuckT's order of fully assembled cards complete. Right now it's a heavy box, and I haven't put together the filter kits/mounting kits yet 🙂
I still have to build some stereo cards, I'm currently running 8 stereo cards through the oven as I type this, and need to build 3 more after that. PBTL cards are all built.
I ran out of ATTiny13's (I have a bad habit of killing the things by accident) so I need to order more to get ChuckT's blank PBTL card order fulfilled and build those extra 3 stereo cards. I'll have those parts in hand middle of next week.
I have parts for 2 extra Pros and 3 extra stereo cards, as well as 3 fully assembled stereo cards in the rework pile. Can probably cobble together another stereo card from salvage. We'll see.
I still have to build some stereo cards, I'm currently running 8 stereo cards through the oven as I type this, and need to build 3 more after that. PBTL cards are all built.
I ran out of ATTiny13's (I have a bad habit of killing the things by accident) so I need to order more to get ChuckT's blank PBTL card order fulfilled and build those extra 3 stereo cards. I'll have those parts in hand middle of next week.
I have parts for 2 extra Pros and 3 extra stereo cards, as well as 3 fully assembled stereo cards in the rework pile. Can probably cobble together another stereo card from salvage. We'll see.
I don't trust the reliability of a solder joint when you start mixing alloys.
If I was reworking a leaded solder joint with lead solder, I'd remove as much lead-free solder as possible, flood the joint with lead solder, remove that, and then make the joint. Then inspect the joint, if it's not shiny I'd remove the solder and reflow it with fresh solder again.
This probably doesn't matter for something like a home audio amplifier, but I'd rather send out the most reliable thing I can.
And goddamn, lead free solder is expensive.
How does this go together with using cheap noname chinese solderpaste with unknown formula?
gmarsh, thanks for your thoughtful and detailed response.
I know SMPSes have been recommended in this thread before. Are there any pros or cons (besides price) of using a linear PSU? Would a linear PSU need to be regulated or would it be possible to get away with a reasonable number of smoothing caps? I'm guessing all of this boils down the the PSRR of the TPA3250?
I'd go regulated if possible.
Couple of reasons - you don't want the voltage on the Pro to go above 36V (or 28V on the classic TPA3118 cards) or bad things can happen. I've seen unregulated "24V" wall adapters put out well over 30V. Having a regulated power supply means the output voltage stays within bounds. The other issue is dropout under high currents. If the power supply voltage drops out under heavy loading, the Pro's turn-off pop protection might get set off. Having a big cap on the output of an unregulated power supply should mitigate this though.
I tend to use SMPSes for everything these days. Mean Well's RS series power supplies are my go-to supply for most things, you can snag them from Digikey/Mouser for pretty cheap, and unless you're building something out of scrounged parts then they're cheaper than a linear supply. I've used Mean Well's gear in countless things over the years, personal and professional, zero issues.
Great!
I received my board.
How should I start my project? Any advice for me?
Thank you.
我從使用 Tapatalk 的 LG-H990 發送
I received my board.
How should I start my project? Any advice for me?
Thank you.
我從使用 Tapatalk 的 LG-H990 發送
Wiener manual is attached. I suppose I could create a build thread, but the TPA3116 thread in the class D forum is full of projects people have put together.
Next step would be to find a suitable power supply, case and connectors. And if you're not driving the amp from a source with a volume control, some means of doing that - either using a separate preamp, or by adding a volume control pot.
bk856er has a pretty great build using a siliconray case:
http://www.diyaudio.com/forums/grou...o-pbtl-editions-available-14.html#post4509691
Next step would be to find a suitable power supply, case and connectors. And if you're not driving the amp from a source with a volume control, some means of doing that - either using a separate preamp, or by adding a volume control pot.
bk856er has a pretty great build using a siliconray case:
http://www.diyaudio.com/forums/grou...o-pbtl-editions-available-14.html#post4509691