DC to DC converter supply issues

[KuusamoMart]

The +/- 9V DC to DC converters are becoming very difficult to procure; suggest changing to +/- 12V 1W converters instead, ensuring 4.7uF capacitors are appropriately rated. The Op-Amps can operate with +/- 15V rails, so there is no requirement to make changes to the amplifier section. As a side benefit, the ILDA specified 10V control voltage range can now be achieved, which was a limitation with the 9V converters.

[Grix]

12V can and has been used interchangeably.
However I must note that there was never any problem with the ILDA spec. I'm guessing the 10V voltage you are referring to is the XY signals, however the differential signal is 10V, meaning that each line is 5V and -5V with respect to ground, so the +/-9V converter has no problem with it.

[TrevorPage]

The BOM already states a +/-12V part, and did so at least as far back as 2022 when I ordered components.

For added information, here in the UK I successfully used Farnell part numbers 3652675 and https://uk.farnell.com/multicomp-pro/mpa0512xt-1w/dc-dc-converter-2-o-p-1w/dp/3652640.

[KuusamoMart]

Ah, the BOM in the repository has been updated, but because I generated the Gerbers in KiCAD from scratch, the BOM only showed the 9V converter. The change needs to be flowed back to the KiCAD design.

[TrevorPage]

Ah, gotcha! Nice to meet someone else building this BTW! (Slight cheeky hijack: If it's any interest, I'm personally using my fork of https://github.com/TrevorPage/laser-dac within my own software for this interface.)

[mael214]

Hi guys !
All of your parts are not longer available.
Do i have to rework the PCB or maybe you have other parts that could fit ?
Kr

[TrevorPage]

@mael214 are you referring to the DC/DC converter specifically?

A DC/DC converter I have successfully used, which is still available, is:

https://uk.farnell.com/multicomp-pro/mpe0512xt-1w/dc-dc-converter-2-o-p-1w/dp/3652675?CMP=i-bf9f-00001000

However, it looks like it's only remaining stocks that are available.

Farnell shows this as an alternative soon to be available:

https://uk.farnell.com/traco-power/tes-1-0522/dc-dc-5v-12v-1w-smd/dp/1635252?MER=sy-me-pd-mi-alte

It is a standardised footprint, so you should find numerous dual-output 9V or 12V DC/DC devices that will fit.

[mael214]

@TrevorPage Yeah sorry :/
This one https://uk.farnell.com/multicomp-pro/mpa0512xt-1w/dc-dc-converter-2-o-p-1w/dp/3652640 you mentionned earlier in the thread is discontinued.

I will check on similar one then !

Thanks a lot !

[TrevorPage]

@mael214 if it's any help, Mouser also stock the Traco part: https://www.mouser.co.uk/ProductDetail/TRACO-Power/TES-1-0522?qs=ckJk83FOD0Xz2aGJiyeZmw%3D%3D

[Grix]

Another alternative for the PSU is Recom R1DX-0512-R.
All the parts on the board have alternatives that are easy to procure, I just ordered a new official batch myself.

[and-pad]

Hi, I recently assembled a batch of 5 Helios boards, and I can't get them to work properly. I can program them, and the software recognizes them, but there's no output at the ILDA port.

I tested the same signal with other Helios units I bought, and it works — so the problem seems to be with my custom boards.

The only difference is that I replaced the obsolete ISA0512-TR with the IAS0105D12, which is listed as a direct replacement. I’ve compared both datasheets and everything looks compatible.

At the moment I don't have an oscilloscope (one is on the way), but I was wondering: has anyone else run into this issue or has any idea where I should look?

@Grix
Thanks a lot!