Hi Guys,
Fortunately, this “work” is my passion and what I love to do. I am blessed in that way. So it’s easy to find the energy to do it. While in the lab, I always play good music on superb amps and fantastic sounding speakers - and that’s one of the perks of being in the lab/listening room. I catch up on sleep as needed and go running everyday to stay healthy and alert. I am careful to avoid burnout. Keeping a good balance of family life and work life is important for longevity.
For any serious SMT soldering job, I like to use hot plate on the bottom and hot air from the top. I have to admit this is a huge SMT PCB. I’ll need to find a larger frypan. 🙂
Fortunately, this “work” is my passion and what I love to do. I am blessed in that way. So it’s easy to find the energy to do it. While in the lab, I always play good music on superb amps and fantastic sounding speakers - and that’s one of the perks of being in the lab/listening room. I catch up on sleep as needed and go running everyday to stay healthy and alert. I am careful to avoid burnout. Keeping a good balance of family life and work life is important for longevity.
For any serious SMT soldering job, I like to use hot plate on the bottom and hot air from the top. I have to admit this is a huge SMT PCB. I’ll need to find a larger frypan. 🙂
Finally, It's good to see someone who thought about the workable size of their SMTs, rather than just use the smallest / cheapest possible "fairy dust" sized parts across the board. There's certainly room for the large size - even mostly TH parts - except maybe the denser areas around the sockets.
I'd like to change a cap from ceramic to film on a HiFiBerry amp. The ceramic part so small, I've neither the tools nor the skill to do so, certainly without making a huge mess. For starters, the last time I touched a SMD film cap with an iron, it turned into a molten blob of plastic. (Others I've had better luck with, but it's still formidable) Too bad I no longer work at Intel, I probably could get one of the rework ladies to swap it for me.
I've read about folks making temp profile reflow ovens out of toaster ovens, using a micro and an SSR in line with the AC. Do you use such a contraption?
I use a dorm room hot plate and skillet on the bottom set to low - and use an IR thermometer to set it to about 140C or right below the safe temp for components (150C). Then I use a hot air SMT rework tool (hot air pencil) to locally heat the spot I want the paste to melt. Use solder paste dispensed with a hand applicator tool. You need good magnifying goggles and good tweezers.
When doing projects with more than 50 components, or if you do this a lot, I highly recommend getting an applicator tool. It gives amazing control and prevents hand cramps.
https://www.tequipment.net/JBC/DPM-...niMciN23Vt_ojCGoUvHFOrFF3QKNLgyBoCj7cQAvD_BwE
For 0402 you need a stereo microscope. I rarely work in that size.
I made some videos on how I do SMT soldering here:
https://www.diyaudio.com/community/...1014d-ims-to-247-adapter.373273/#post-6939125
When doing projects with more than 50 components, or if you do this a lot, I highly recommend getting an applicator tool. It gives amazing control and prevents hand cramps.
https://www.tequipment.net/JBC/DPM-...niMciN23Vt_ojCGoUvHFOrFF3QKNLgyBoCj7cQAvD_BwE
For 0402 you need a stereo microscope. I rarely work in that size.
I made some videos on how I do SMT soldering here:
https://www.diyaudio.com/community/...1014d-ims-to-247-adapter.373273/#post-6939125
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I saw how C13 moved to square up to its pads. Well, I have the hot air pencil tool. I'll have to give this a shot sometime to see if I too can make such an assembly. As far as changing the one component on the already assembled amplifier, I'd dread wiping out everything nearby. "C'mon, come off already!"
On the bench is the PSU board for the Bob Carver RPM V12 preamp. I just finished placing the SMT components on the bottom side of the board. There is a HV circuit here. Getting ready to hot plate/hot air these boards.
SMT soldering completed now moving to TH parts. Those big caps are 0.47uF 600v! We have some high voltages on this board up to +370v for the B+.
There was a 1N4148WT diode in SOD-523F-2 package. It’s about the same size as an 0402 chip resistor (technically it was about 0503) but with little SMT legs that make it wobble. I had to get the microscope out to see the cathode band.
Well, I was listening to a cassette tape this afternoon on my lovely Technics RS-TR333 dual tape deck.
Halfway through the tape, I heard a soft clicking sound, the tape still played fine.
I got this deck back in 1994 for about $200, and it's served me flawlessly over the decades.
Seems I got hit with the dreaded intermediate-gear syndrome! (part # RDG5772ZC)
Oh lordy, on the bench it went, got the mech out, and indeed that gear was missing a tooth!
It's made of soft plastic for quietness in running, but a weak part no less.
The belts are still in perfect shape though.
The only replacement gear is by someone in the Cheque Republic/Poland area who makes an improved durability 3D printed version.
Ebay sells them.
Take a couple of weeks to get shipped to the US.
I'm ordering two gears, might as well be proactive and do the other mech while I have the unit apart.
Halfway through the tape, I heard a soft clicking sound, the tape still played fine.
I got this deck back in 1994 for about $200, and it's served me flawlessly over the decades.
Seems I got hit with the dreaded intermediate-gear syndrome! (part # RDG5772ZC)
Oh lordy, on the bench it went, got the mech out, and indeed that gear was missing a tooth!
It's made of soft plastic for quietness in running, but a weak part no less.
The belts are still in perfect shape though.
The only replacement gear is by someone in the Cheque Republic/Poland area who makes an improved durability 3D printed version.
Ebay sells them.
Take a couple of weeks to get shipped to the US.
I'm ordering two gears, might as well be proactive and do the other mech while I have the unit apart.
That looks pretty tricky. I hear cassettes are coming back. I still have a Philips dual tape deck from 1994. VHS HiFi (analog) is also a great option. It has better performance specs than reel to reel because it is helical scan. 20Hz to 20kHz flat.
Yes, it is tricky, however that video is of a non-reverse deck - same basic mechanism, but mine uses a second pinch roller at the other end of that chassis, and a second capstan/flywheel, along with a 180 degree rotating head assembly.
There's additional levers and linkages involved for that.
I've just ordered the pair of new replacement gears from that Poland supplier on Ebay (Epray).
Total cost w/shipping/tax $26.23
I'll tear the other mech out later when I get the gears. - sometime in mid July.
On the digital bench is a revised layout for the A40 amp with built in power supply and long format to free up real estate on the floor panel of the amp.
On the actual wooden bench, on the A40 prototype, I replaced the (suspected fake Fotek) SSR with a different brand that was supposed to be a genuine Fotek but it came unbranded but seems work well. This unbranded unit appears to be built with higher quality (these are my observations on what a “real” one looks like: the plastic shell is one piece and the terminal bolts are sized smaller for the control wires, the heatsink pad appears to be chrome plated, there is also a threaded hole protruding from the middle of the heatsink pad and a digital pattern laser etched in the bottom) and the amp is now much quieter. Less mechanical buzz from the trafos and the sound is hum free with ear 6in away from cones. I am measuring 0.2mV rms output noise on the speaker binding posts now with input DAC not playing. I think this SSR has a better zero crossing switch circuit. I took the opportunity to connect the standby LED and added the mute toggle switch to control the AC input to the low capacitance PSU for the speaker protect SSRs. It works like a charm.
Revised layout for A40:
On the actual wooden bench, on the A40 prototype, I replaced the (suspected fake Fotek) SSR with a different brand that was supposed to be a genuine Fotek but it came unbranded but seems work well. This unbranded unit appears to be built with higher quality (these are my observations on what a “real” one looks like: the plastic shell is one piece and the terminal bolts are sized smaller for the control wires, the heatsink pad appears to be chrome plated, there is also a threaded hole protruding from the middle of the heatsink pad and a digital pattern laser etched in the bottom) and the amp is now much quieter. Less mechanical buzz from the trafos and the sound is hum free with ear 6in away from cones. I am measuring 0.2mV rms output noise on the speaker binding posts now with input DAC not playing. I think this SSR has a better zero crossing switch circuit. I took the opportunity to connect the standby LED and added the mute toggle switch to control the AC input to the low capacitance PSU for the speaker protect SSRs. It works like a charm.
Revised layout for A40:
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I really like that layout, will that be something you'll eventually sell on your store, or will that be strictly for the A40 commercial product? After I finish my current amp projects I plan to dive into an Alpha Nirvana.
I've noticed much of the same comparing my I think authentic Fotek to for certain fake ones. Your description in general matches my Crydom's I picked up off digikey. Comparing the Crydom to the Fotek This makes me wonder if developing some sort of versatile zero crossing SSR board would be worthwhile. Maybe something that includes an always on PSU for low voltage power switches, and support for a trigger input.
I've noticed much of the same comparing my I think authentic Fotek to for certain fake ones. Your description in general matches my Crydom's I picked up off digikey. Comparing the Crydom to the Fotek This makes me wonder if developing some sort of versatile zero crossing SSR board would be worthwhile. Maybe something that includes an always on PSU for low voltage power switches, and support for a trigger input.
I actually have that already in the SFP - and the new “+” version has external control for on/off and logic for driving speaker protect SSR. It uses a discrete triac for the soft start and dual low RDson MOSFETs for the main power on/off. The MOSFETs stay on once soft start is completed so no noise at al.
But a version that drives an off board Fotek style SSR is a good idea.
I am not sure if this one piece A40 will be offered in my shop. Probably not as one can simply get the Alpha Nirvana amp board already.
But a version that drives an off board Fotek style SSR is a good idea.
I am not sure if this one piece A40 will be offered in my shop. Probably not as one can simply get the Alpha Nirvana amp board already.
Looking forward to the "+" model of the SFP, in my head I was thinking of using the SFP schematic as a starting point, but you are well ahead of me 😀 I think I'll try my hand creating something that drives off board puck style SSR's one of these days.
A40 is based on Alpha Nirvana with built in PSU. Alpha Nirvana is SE push pull. Only one of the outputs is actively driven by the VAS. The other is similar to Aleph active CCS but uses P-MOS for the active CCS output. Alpha Nirvana is good for about 40w with +/-27v rails.
On the bench tonight is the PSU for the Bob Carver RPM V12. I finally got the missing Wurth terminal blocks and the Meanwell AC/DC 5v always on supply. Will test it tomorrow. All soldered up for now.
Just to say well done on this:
http://v2.stereotimes.com/post/lsa-signature-50-loudspeakers-by-terry-london/
http://v2.stereotimes.com/post/lsa-signature-50-loudspeakers-by-terry-london/
On the bench tonight is testing the PSU for the Bob Carver RPM V12 preamp. Looks like we have 370vdc for B+, 44.7vdc for the headphone amp, and 12.85v for the filament heaters. The regulation is clean and the slow ramp up with the cap multipliers are nice and slow over 20 seconds. The clamp on meter registers 0.3A but that doesn’t match the wattometer which only says 8W at the wall.
