Interesting you're dissatisfied with the 858D. I too have one of those plus additional nozzle. Don't use it for anything really sophisticated but find it quite well suited for the occasional job of removing something of the size of 44pin QFPs or smaller. And for the money saved compared to a proper tool you can pay someone to clean up your desk for years.

?

?

?

--

Brendan

On Wed, Nov 13, 2024 at 02:40 PM, George Cushing wrote:

Yeah and clean, well organized?workplace.

On Wed, Nov 13, 2024 at 01:25 PM, George Cushing wrote:

?Another secret is to wick as much of the original solder off as possible. You're never going to get to clean copper, but that's not necessary. Otherwise you risk bridging.?

Here was my first attempt at Gemini dsPIC33 removal (with Brendan's invaluable help) :)

?

On Mon, Nov 11, 2024 at 03:47 PM, Stephan G wrote:

The big advantage is that no significant amount of flux gets underneath the package where it is almost impossible to remove by simlply cleaning with IPA. As some flux residue are becoming hygroscopic over time, having no flux residue on a PCB can be a big advantage if the PCB is used in humid air / outside.

I never worked on Gemini units, but from my experience I agree with not using solder paste without a stencil. Trying it without stencil only needs much more time applying the paste and then for cleaning up the mess afterwards without any advantage. For small pitch ICs like the approx 25mil SSOP of the FT232 I think drag soldering is the most efficient if not the only possible way of hand soldering. For larger pitch packages like 50mil TQFP or SOIC however I reverted to soldering pin by pin using 0.5mm solder and a cheap stereo microscope or strong glasses. This way with a bit of practice no addl flux and no solder wick is needed. The big advantage is that no significant amount of flux gets underneath the package where it is almost impossible to remove by simlply cleaning with IPA. As some flux residue are becoming hygroscopic over time, having no flux residue on a PCB can be a big advantage if the PCB is used in humid air / outside. I'm not sure whether this is relevant to Gemini units at all, but for battery powered sensors for example flux residue becoming moist can increase sleep current considerably and significantly shorten battery life. Went through this myself...

?

Regards,

Stephan

?

I’m sure it was just my amateur skills, but all solder paste helped me do is bridge all the pins together in one shot ;) I’m sure a proper stencil would’ve helped, but drag soldering worked first and every subsequent time I tried.

?

Regards,

?

? -Paul

On Mon, Nov 11, 2024 at 06:47 AM, Paul Kanevsky wrote:

Have to say, drag soldering is an amazingly effective technique. The few SMD chips I replaced previously were always a struggle, and I tried solder paste and soldering individual pins. Drag soldering literally takes less than a minute, requires very little cleanup and produces high quality, good looking joints.?

?

I had been using reflow techniques with a rework station which works perfectly on high density packages. Solder paste works very well where you need to set up many pads for a single device.? ?

?

--

?

?

?

Have to say, drag soldering is an amazingly effective technique. The few SMD chips I replaced previously were always a struggle, and I tried solder paste and soldering individual pins. Drag soldering literally takes less than a minute, requires very little cleanup and produces high quality, good looking joints.?

I draw the line at 20-30 pin packages. Don't even want to think about replacing a 128 pin ARM chip :)

?

On Sun, Nov 10, 2024 at 06:25 PM, Brendan wrote:

Yeah Paul has been doing his hand at some G2 ICs R&R and is doing well (another notch in his belt of skills)! David partridge, Michael and I and even others, Losmandy!. ?Many electronic repair places don’t like to touch these as they don’t understand the system or quote the $100+ per hr repair rate nor do they don’t have ICs in stock or access to inbuilt firmware, like dspic33s...and many others.? They couldn't replace the ARM and load in the very specific bootloader (firmware), so the main firmware can be uploaded by SD card and GFU. This is propriety as indeed in reality so is the dspic33 firmware.

Hard to say what this issue is but think it’s one of three (in order) the DsPIC33 IC, U6 buffer IC or lastly "H" bridge (unlikely but possible).? If it was a "tallboy" I'd be first straight to the socket joints!????

?

Repairing is not only replacing, its also keeping spares in stock on hand ready.?? Also the ability not to damage the PCB under repair, lift pads, damage tracks as you want these PCBs to last and in general most are fully repairable and indeed have user lives of decades (just look at the G1s).?? It just takes time to repair, which I can understand is the issue for the user!??? But most repair time is post repair testing...to ensure its Good to Go "GTG" (I hate to send a repair that bounces (for any reason...its frankly embarrassing and not professional).?? That's why the repairers test units to an inch of their lives; have the circuit diagrams; ICs on hand ready to use; firmware' from factory and writers.....and working knowledge of the circuitry as they are users as well.

?

Repairers and software writers are in constant contact with each other on FW changes, possible system mods, updates all things Gemini etc.?? One aim....a better system and continuing support!

?

FWIW......remember these are repairable at much lower costs than new.?? But yes I understand users finding Turn Around Time (TAT) frustrating.

--

Brendan

On Sun, Nov 10, 2024 at 04:37 AM, Paul Kanevsky wrote:

On Sun, Nov 10, 2024 at 12:29 AM, John Kmetz wrote:

The PCB components are machine soldered at the manufacturer and are extremely difficult to remove and replace by most people. Brendan Smith apparently has the skills to do this though you would need to pay for the round trip to Australia, plus cost of repairs, and the incur the travel times as well

David Partridge, in the UK can also do PCB repair work.?

?

For a skilled small electronics person SMD repairs are not a big deal. But you 100% need a good SMD rework station and some reflow materials to put them back together.? There are also some health and safety issues that push it out of the realm of the casual electronics hobbyists as the investment needed is kind of steep unless you use it often.?

?

--

?

?

?

On Sun, Nov 10, 2024 at 12:29 AM, John Kmetz wrote:

The PCB components are machine soldered at the manufacturer and are extremely difficult to remove and replace by most people. Brendan Smith apparently has the skills to do this though you would need to pay for the round trip to Australia, plus cost of repairs, and the incur the travel times as well

Fritz,

?

Glad you got it worked out though you had to buy the replacement. The PCB components are machine soldered at the manufacturer and are extremely difficult to remove and replace by most people. Brendan Smith apparently has the skills to do this though you would need to pay for the round trip to Australia, plus cost of repairs, and the incur the travel times as well. At least you can start like new now and have confidence in the mount performance. My second PCB board has never failed in the 3–4-year period since I did my replacement.

?

Good luck,

?

John

?

--

_____________________________________________________________________________________________________________________________________________________________________________

Losmandy G11G2 on pier; refurbed Losmandy G11 with OnStep controller; SkyShed design roll-off observatory; ZWO ASI2600MM-P; ZWO ASI071MC; Sky-Watcher Esprit 100 ED with field flattener; Celestron C925 Edge HD with 0.7XFR, William Optics Zenithstar 61 APO; PHD2, NINA, Sequence Generator Pro and PixInsight user

Alright, thought I’d close this out.?

New board installed and zero issue now with the mount. Swings the RC10 around easily and guiding last night seemed to be alright (bit of clouds and only initial alignment).?

I’m thinking I’ll donate the old board to Michael Herman and he can do what he sees fit with it. Maybe there are a few components still good on it he can use to fix other boards.?

On Mon, Nov 4, 2024 at 03:01 PM, Fritz wrote:

Thank you all again for the incredible amount of background and help! I talked to Michael Herman in detail on the problem and it was decided that likely the best course of action is a replacement board.

?

As John Kmetz pointed out a replacement board used to be $300 which imo is a very fair price or a board with common parts and in production so long. It is now $700 for just the board.?

Sometimes it is a trade off of time vs money with enjoyment of a hobby, and in this case I do not have the time go down a potential rabbit hole with the board and miss out on the imaging season in Florida. I skipped last years imaging season to build my new observatory so I’m really looking to start imaging again.?

I’m certainly confused why the board is so expensive now and it leaves a bad taste in my mouth but it is what it is. I was also unable to get a hold of anyone at Losmandy since the beginning of this post (email or phone). The board was ~7 years old and always kept in an environmentally controlled environment. My observatory has both an air conditioner and a dehumidifier.?

Thank you all again for your help and giving so much to the community. I’ll report back if this is the fix. Looks like the replacement board shipped out today.?