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B&W-tech Spectrometer & 473 module: Setup+Mods+Info

uk-laser

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Nov 5, 2018
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9
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That's unfortunate.
I guess the only options are reverse engineering the CPLD or a MCU alternative.
Well, there's the excuse to upgrade my 8ch USB logic analyser to a 16ch one.
 



uk-laser

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Nov 5, 2018
Messages
9
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Tracing out the board to get connectivity to the CPLD, I tracked the ADC 16 bit bus to the 2 FIFOs (2k x 9).
FIFO read port goes directly to the 8051. Unfortunately, there I came unstuck. I found 3 sequential data lines shorted together. Lifting the respective FIFO, the shorts remained. The 8051 still runs and communicates over the UART, but it looks like the 12V over-voltage took out some GPIO drivers. Another factory programmed device. Since a sporty, modern, micro with external 16 bit ADC could mop-up the entire board, I don't think I'll be continuing with reversing the CPLD.
 

kecked

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Jun 18, 2012
Messages
388
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43
I saw some diy ardunio two chip,solutions on the web. Just search diy spectrophotometer. Looks really easy to implement and then you can code your own software anyway you want.
 

chloderic

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Jan 21, 2018
Messages
319
Points
43
Bit of a long shot, but hoping someone here may be able to help.
Anyone have any scrap B&W spectrometer PCBs from one of these units, perhaps with mechanical damage or missing / damaged optical assembly? Specifically I’m looking to recover one or two pieces of U401 IC, Xilinx XC9536. This is a B&W programmed part so can't just get one from Farnell.

A bit of background - I’ve been passed a friends spectrometer to repair. It had been connected to 12V rather than 5V.
When I powered it from a bench PSU set to 5V, 1A limit, the PSU went to current limit at just under 1V.
Thermal photography showed only one IC getting hot, that being the Xilinx XC9536. Removal of this IC returned current consumption to near normal, and allowed communication via RS232, indicating a fair chance of returning to normal operation if U401 is replaced.

Thanks in advance...
Robin

Hi, due to some consecutive private disagreeable events I had to pause a little here and find it time to return to life again. I will now primarily deal with the topic of raman spectroscopy and have already constructed a few more parts, but later elsewhere ...
Now to this question, I still have a board with drastic timing problems that I could give up, but I do not know how much that costs freight to UK ...
 

Richard A

Member
Joined
Jan 29, 2018
Messages
42
Points
8
Tracing out the board to get connectivity to the CPLD, I tracked the ADC 16 bit bus to the 2 FIFOs (2k x 9).
FIFO read port goes directly to the 8051. Unfortunately, there I came unstuck. I found 3 sequential data lines shorted together. Lifting the respective FIFO, the shorts remained. The 8051 still runs and communicates over the UART, but it looks like the 12V over-voltage took out some GPIO drivers. Another factory programmed device. Since a sporty, modern, micro with external 16 bit ADC could mop-up the entire board, I don't think I'll be continuing with reversing the CPLD.

I've been looking at MCUs with 16bit ADCs, but the ADC spec usually isn't as good as stand-alone ADCs:

https://www.mouser.com/Semiconductors/Embedded-Processors-Controllers/Microcontrollers-MCU/_/N-a85i8?P=1yrfw6s&Ns=Pricing|0



A PIC24 with one of these probably would get the job done:
https://www.mouser.com/ProductDetail/Texas-Instruments/ADS8866IDGSR?qs=sGAEpiMZZMtTlwiyc7n6Sp4JfDEGO4pJjlSwEKOJtjg=

I don't know if the $42 LTC1605AISW ADC is still good on my board or not.
The ADS8866 is about 1/10 the cost with similar noise specs, if not better.
 

Richard A

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Jan 29, 2018
Messages
42
Points
8
I've been working on an inexpensive dsPIC/PIC24 based controller for the spec.
Either the internal 12-bit ADC of the MCU or the 16-bit ADS8866 can be used.
Other than the MCU and optional 8866, the only other ICs are an opamp and two VRs.
For the serial interface, I'm using a voltage divider and a 3904. I don't plan on driving long cables.
I did not include the recommended vref circuit for the ADS8866, but if someone wants to add it, feel free.
I'll be ordering 10 PCBs from itead. 50mm x 50mm.
Assuming it cost $14 for 10 PCBs, I'll send the remaining boards to anyone who wants one for 2$ ea + postage.
Links will be provided to the firmware and PCB files when I'm done.


SpecDrv.png

SpecDRV2.png
 

Civitus

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Joined
Mar 1, 2017
Messages
77
Points
8

Civitus

Member
Joined
Mar 1, 2017
Messages
77
Points
8
Regarding the alignment, I have developed a compensation optics to replace the LPF. It should solve the focus shift issue (pretty much to a level tolerable within a few dozen microns). Kindly let me know if anyone is interested in since I got plenty these optics made.
Hi, can you tell me more about these replacement optics, please?
C
 

paul1598419

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Sep 20, 2013
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15,211
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The thickness of the grating should have no effect over its ability to work in the spectrometer. I would be more concerned with the blaze wavelength.
 

Civitus

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Joined
Mar 1, 2017
Messages
77
Points
8
The thickness of the grating should have no effect over its ability to work in the spectrometer. I would be more concerned with the blaze wavelength.
Hi Paul,
I do agree with you, in point of view of diffraction, but in terms of focusing le light the thikness may play some role as the light path will be shorter ... don't you think ?
and,.
and 3mm (the one inside the spectrometer has 3mm thikness, and the one available has 6mm) over 20mm (approximatly the light paths) between mirror and gratings, it gives 1/6 of the path light m and i am scared that this will affect oll the optical paths inside.
It is why i want to know if some one has changed the gratings, and wich thikness he has use for this.
Thanks again paul for the help.
C
 

paul1598419

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Sep 20, 2013
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That is the reason for the focus mirror in your spectrometer. Even if you had a B&W Tek grating with 600 l/mm you would still need to refocus. Anytime you change something in your spectrometer's optical bench expect to do a realignment. They are never fun and can be very frustrating at times, but it is what it is.
 

chloderic

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Joined
Jan 21, 2018
Messages
319
Points
43
That is the reason for the focus mirror in your spectrometer. Even if you had a B&W Tek grating with 600 l/mm you would still need to refocus. Anytime you change something in your spectrometer's optical bench expect to do a realignment. They are never fun and can be very frustrating at times, but it is what it is.
Yes Paul .... so it is .... not nice to do it and you may need some beer to do it .... and than ... it will not be easier.
 

paul1598419

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That is hilarious. I don't drink, but I can imagine trying to realign the optical bench while intoxicated. You might end up with a worse conditin than when you started.
 




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