Help driving GSI 120DT Galvo motors

[thorson14]

Hi Steve,

I could hardly read it myself in person. I confirmed the number with a couple set of eyes in my lab.

The chip reads:
DAC7802KP
99170363


Thank you,
Todd

[mixedgas]

That just made reverse engineering considerably easier..
Its a dual Multiplying Digital to Analog Converter. With 12 Bit latching parallel inputs.

The two LT1057s right next to it mostly like convert the MDACs current output to a voltage and that voltage, after adding offset and level controls, drives the Galvo amps.




See attached...

[mixedgas]

Driver Amplifiers used in Galvo Amp Final Stage..
PA1 Data sheet

https://www.apexanalog.com/resources...s/pa01-73u.pdf

Steve

[thorson14]

Hi Steve,

I see the LT1057s you're referring to, great news. Thank you for the documents and info on the converter and amps.

I am wondering where I will be tapping into the board to send my signals. If I'm going to plug the board into the controller tower backplane for power purposes, is there a connection to tap into on the board anywhere?

Thanks again!
Todd

[mixedgas]

The connection if analog would be around the 1057 OPAMPS.. That is why I asked about the DAC chips. You'd need to "lift" a part or two to enable the connection. Due to the multilayer board, I cant make that determination from just the pictures, I need to probe it with some tools I have.
!
You have several senior electronics technicians in the College of Engineering at Irvine. You need one with really good board level soldering skills. We're at the point that I could walk one of them thru this in a email or two or three, or in a phone call.. Either that or it needs to come here.
!
Steve

[thorson14]

Okay I will contact an appropriate person with expertise in board level soldering skills within the college here. I have quite a few contacts already in mind. Can you tell me what tools will be required so I can confirm my contact has them here?

Thanks again,
Todd

[mixedgas]

That is old technology, A desoldering station with vacuum is all that is needed, plus a voltmeter. Assuming you will use the confocal microscope's existing power supply by plugging the card back into its bus slot.

Steve

[thorson14]

Hi Steve,

I have my feelers out for help with the desoldering station with vacuum. I had planned on using the original controller tower for the motors' power supply.

I wanted to clarify a few things after researching these OpAmps today. Please correct me if necessary...but from what I've gathered, we will be heating the 8 pins for the LT1057s (both OpAmps that then signal to the X and Y channel portion of the motherboard I'm assuming?) simultaneously so the OpAmp can be lifted up to expose the pin connections. Then we will test these connections (I'm not sure where we will be connecting the voltmeter during this connection testing portion) and determine where we can connect to for sending our sine waves from our custom software/DAQ setup to scan the laser with the mirrors mounted on the galvos. I located the pinout information for the LT1057CN8 OpAmps:

Am I doing okay so far?
Once we find the correct pin connections, will we just connect to the frequency (analog) side of the OpAmp or in this case, will we even need the OpAmp there? I know I might be getting ahead of myself - I need to find somebody to get these components lifted first - but I'm just trying to look a few steps ahead and make sure I'm understanding everything myself before getting into gritty details with my PI.

Thank you,
Todd

[mixedgas]

Were not lifting the opsmps.Odds sre We will lift one component.

[thorson14]

Okay good - I will write once I locate some de-soldering help. Hopefully I get some responses tomorrow morning.

Thank you,
Todd