JoaMat

OK, I'm trying and hopefully learning something, with solder paste and component in place and then hot air. What temperature and airflow did you use? Also what type of solder paste?

Michael, Add 2 mini T2 boards. Thank you, Joachim

A few years ago I bought a Weller hot air station WTHA 1. It was my first hot air station and I thought it was a good station. It was quite expensive so it had to be good! Suddenly the display showed “Error 3” and nothing more happened. No guarantee left and I couldn’t remember from whom I bought that crap from. After some investigation I bought a Quick 861DW. Now I’ve used the Quick for a while and I’m very happy with it and it costs a third of the Weller - and ten times better. I use a Weller!! solder station for smd soldering and have no intention to change that. But when working with the Quick hot air station the last days I tried to solder components with the Quick and it did work quite well. So, first I thought this is a complicated way to solder smd parts.. … but I now I’ve changed my mind, well worth trying – Thanks for sharing this, James.

Nice! I like them chassis.

Milled a new “corrected” board on Sunday. When populated and ready for test the bloody thing worked fine for a few seconds than it started to decrease voltage slowly down to 230 volt or so. I started to change component by component and when just a few unchanged I replaced the dn2540 and issue solved, phuuu. Anyhow. Now the regulator seems to work alright, okey just 10 – 12 mA of load. With trimmer (200R) there is a range of 5V at 400V. Picture shows 400.0V and after 20 minutes the meter in “minmax” says average 400.0V within -0.0/+0.1.

Now it’s tomorrow and it turned out to be long day. My work flow nowadays is first schematic and then board layout. The idea is that I can’t make a board that doesn’t follow the schematic and in the end minimize board errors. And it actually reduced my errors to almost zero… but an error in schematic will guarantee a board that is schematically error free but also something that doesn’t work properly. Two errors in schematic are now corrected and the little thing works like charm. By the way - yesterday was a Friday 13th, wasn’t it?

Shit! While looking at the left picture above something seemed to be wrong. Hmm, so-8 at upper left trace to pin 2 should go to pin 6..... have to fix that, tomorrow

Today’s exercise. Milled a double sided board and populated it. Now I know it’s fairly easy to solder this by hand. If you can solder a mini T2 board the GRHVxxx boards shouldn’t be much of a problem. Besides it’s funny. This board is essential the same as Kerry’s except no enable and a trimmer to adjust output voltage. Thanks for those mini boards Kerry.

Here is a PCB with unnecessary area. A big metal saw and it’s fixed in a couple of minutes.

I’ve got questions about using +/-450V supplies with mini T2. It would probably work alright, I can’t see why it wouldn’t. If using a drop down resistor for +220V there is a Vishay 24.9k/3W that probably will do (haven’t tested it - maybe I should or someone else). One other request is the location of stand of holes. Attached are templates for left and right boards - imperial and metric. I had to print them 100.4% to get scale 1:1. They don’t look nice but that is what I managed to do in Proteus. holes mini T2 Right v.23.PDF holes mini T2 Left v.23.PDF mm holes mini T2 Right v.23.PDF mm holes mini T2 Left v.23.PDF

Folks with DIY T2 are used to “switch off thump”. I don’t know if anyone have solved the issue with the real thing. I use a T2 PSU with my mini T2 and when switching off the sound just dies out nicely without any thump. T2 PSU has much less capacitors than later GR supplies which probably explains the no thump. Glad you solved the switch off thump so nicely and easy.

Bare boards, please.

mini T2 v.23. Changes from v.22 Ground plane at area for brackets removed. Silk screen lines 20mm from long side edges, cut here if you want transistors mounted direct on heat sinks. Then you also have to run wires for +B traces just been cut. Be careful you are now close to other traces - only for DIYers. Regarding wishes for tblocks I want to quote myself (from a private conversation oct. 2018) “I haven’t used them at all with amplifiers and I have never missed them. Advantages are: - you can route the wire to the spot where it’s wanted, – the connection is much safer than with tblock, - saves space, – with a desolder gun or a solder iron they are easy and fast to “disconnect”. This also what Kevin did with his DIY T2 except for the outputs to earphone. With power supplies I use tblocks, then I find them convenient. Bottom line - IMO – tblocks destroys a layout.”

On GRHV regulator board – is there a capacitor C2 between source Q3 and emitter Q4? If so - reason?

Here is a picture of my third mini T2. Area for heat sink bracket screw holes cut away. Board now 160mm x 80mm and transistors mounted direct to heat sink. Inner dimension of case is 200mm x 161mm. This is the way I’ve built my amplifiers for some years now. There simply is no room for terminal blocks – will only make things more complicated for me. The real thing - DIY T2 has no tblocks either (except for output to Stax connector).

OK, time to bring this thread up on the first page. I think this is one of the most interesting threads after “The ultimate DIY? A Stax SRM-T2!“ (alright, there are lots of interesting things on HeadCase). Here Kevin introduces GG, sandwich, DHT, T8000DR etc., etc..

Any chance for a GRHVxxx BOM?

Looks even nicer today. But my brain is about to overheat – how does the probe work?

Here are some files, the best I could find. kgsshvproductiondualmot.PDF kgsshvps8g.PDF kgsshvBOM.xlsx The BOM has to be reworked with the components you want to use. Some might be harder to find. Take look and see if this is useful.

Happy Birthday, Sir!

After looking at posts by Kerry regarding the GRHV boards I think it might be a good idea for builders of the mini T2 to even build Kerry’s regulators. To me those boards seems doable and they aren’t any more difficult than the amplifier boards nor significant higher voltages either. The more you solder the better you get at it.

Good to know that 10th worked for you. I didn’t dare to buy smaller than 15th even it’s a short flute. When I did my digital attenuator I had 10th clearance so I had to make a conventional chemical etching. Same here, no luck with the V shaped things – probably only for the pros.

Looks nice! What tool did you use? I use 15th end mill but as I understand V shaped tools are more commonly used.

https://static.qobuz.com/goodies/39/000101993.pdf

I believe Kevin has made more than a couple of versions of the KGSSHV. If you post good pictures of your boards I’m sure people here can help you.