Heres my solution to fitting the BD237 to the NCC200. It goes in the same place as it does in the Qudos. As you can see I drilled three holes just in front of the heatsink. That's it!
You might just have to sneak that 220nf cap forward a touch but there's plenty of room for it. Flying leads will go under the board.
Here's the solution that I settled on for TR5
https://flic.kr/p/2jgoDCu
I was thinking about converting these version 1.4 boards to Qudos a while back, along the lines that Chops54 is describing
This gives me the confidence that it can be done, thanks Chops54
Remember that TR5 will need to be electrically isolated from the heat sink so check the mounting pad for continuity with a meter as there are different types
For some reason my DVMs are refusing to measure anything when put in the +ve line and it looks like they are not passing the supply voltage through either. Odd. If measuring across the +ve emitter resistor I'm assuming around 26mV is what we're looking for?Your welcome James. Front end pulls roughly 12mA. Alan uses two DVMs when he sets his.
Luca, the picture that I have linked to is a v1.4 Board that has been changed to v1.5 with the exception of a 330pf and a 3k that need changing to 220pf (C14) and 2k7 (R12). (R2) 22k has been changed to 1k, (R23) 2k2 changed to 1k2 and the bias current wound up to 130maHi Mark, nice and easy solution.
I see you have not still removed R4, R27, C9 and C10 from the converted Qudos board. Is it not worthwhile?
Luca, the picture that I have linked to is a v1.4 Board that has been changed to v1.5 with the exception of a 330pf and a 3k that need changing to 220pf (C14) and 2k7 (R12). (R2) 22k has been changed to 1k, (R23) 2k2 changed to 1k2 and the bias current wound up to 130ma
I was also advised that R4, R27, C9 & C10 could be removed on the Qudos boards, doing so adds a further degree of refinement. It’s also worth pointing out that all of these mods are applicable to the HackerNap. There was a little discussion on here about the paralleling of output transistors
It was also suggested to me that R4, R27,C9 & C10 could be safely removed on Qudos boards but have seen that they are back in on the latest production run as seen on the Facebook page. However I’m not sure what would be the effect on NCC200 boards and without having the necessary measuring equipment to check the stability I would not make that change. I’m sure that there are others on the forum that would have more of an idea.
With regard to setting the bias on a Voyager I used two meters and added the readings together to get the 36mA that was recommended
Yes, supplied as bare boards. But not recentlyCan I ask if you bought those direct from Avondale?
JamesFor some reason my DVMs are refusing to measure anything when put in the +ve line and it looks like they are not passing the supply voltage through either. Odd. If measuring across the +ve emitter resistor I'm assuming around 26mV is what we're looking for?
Thanks Alan, yes, I was thinking the same. I'll have to check that. The boards have been built and used for some time now, just putting in a new case, so just double checking everything. Using the emitter resistor method I'm showing about 122mA on each channel.James
Sounds like the DVM internal fuse has blown for your DC Milli Amps range ?
Alan