Raytheon PalmIR 225 teardown, level function issue - Page 1
Forum section: electronics / general

author: Spirit532
author_rank: Frequent Contributor
timestamp: July 08, 2019, 08:36:15 pm
content: So I just received a Raytheon PalmIR 225 that is more or less dead, from someone who hopes it could be repaired.The camera is more or less on its last dying breath in terms of the chopper wheel, but the optics and BST sensor seem to be working fine. There's only one issue - the image isverydim, only becoming useful at around 200C.The on-camera GUI has a "LEVEL" control which I'm assuming is supposed to set the range, but it's simply not workingat all, while all the other features are functional(focus, gain to an extent, viewfinder brightness).Does anyone have any experience with these devices?Here's a few photos:Left:https://i.spirit.re/NY5mV.JPGRight:https://i.spirit.re/lHfJ2.JPGSensor:https://i.spirit.re/gWlhu.JPGBack with micro CRT:https://i.spirit.re/1WwCF.JPGTop of the lens block:https://i.spirit.re/eX5PV.JPGBottom of the lens block:https://i.spirit.re/jMkRx.JPGCard cage:https://i.spirit.re/pOaiP.JPGPower board, side 1:https://i.spirit.re/1mPbE.JPGPower board, side 2:https://i.spirit.re/tikoZ.JPGDSP board, side 1:https://i.spirit.re/ANkFf.JPGDSP board, side 2:https://i.spirit.re/pFkZ2.JPGLeft housing:https://i.spirit.re/sRj8Z.JPGIO ports:https://i.spirit.re/4SAe4.JPGSeems like there's a digital communication port, maybe someone got in and disabled the level function?Everything looks to be in perfect condition other than the chopper wheel, but the image is still extremely dim, with or without it.

author: Fraser
author_rank: Super Contributor
timestamp: July 08, 2019, 09:33:24 pm
content: I presume you have already found the manual ? The PalmIR 225 is very similar to the PalmIR 250 so this manual applies.....https://www.x20.org/wp-content/uploads/2014/11/250-USER-GUIDE.pdfA very low contrast image that responds only to high temperatures can suggest loss of vacuum in the BST sensor. The BST core in this camera is the same design as that used in the EEV Argus 2 and 3. It was also used in the ISG Talisman BST. The cores basic design also appears in the Thermal eye 300 and Cadillac DeVille camera. They are all part of the Raytheon BST core kit range.Sadly the exact cause of your ‘patients’ problem is not easy to remotely diagnose and you will not find public documentation on the Raytheon Core, it’s I/O or the control signalsRaytheon take their documentation security very seriously. There may be some information on the power and video connectivity of the core that can be shared but Raytheon never released the schematics of their core PCB. There is a composite video output available on the PCB edge connector but that will just prove whether the defective image you are seeing on the EVF and RCA video output is what is coming from the corer a later video processing stage.Fraser

author: Spirit532
author_rank: Frequent Contributor
timestamp: July 08, 2019, 09:38:10 pm
content: Loss of vacuum might be a thing I can restore, since I'm building a UHV pumping station.However, why would the LEVEL setting not doanything?And is there any info on interfacing with these cores to adjust deeper settings/see diagnostics?

author: Fraser
author_rank: Super Contributor
timestamp: July 08, 2019, 09:46:49 pm
content: Is there a level change indicator on the screen that shows changes in the setting ? If so, then I agree that it is strange that the Level control has no effect as it is a software function. Is the unit set to manual mode for manual adjustments ?Fraser

author: Spirit532
author_rank: Frequent Contributor
timestamp: July 08, 2019, 09:53:40 pm
content: There's no indicator, sadly. The unit has an auto mode and a manual mode, the level/gain are only adjustable in the manual mode. I can adjust the gain, but when I move the cursor to level, the +/- buttons simply do nothing, or perhaps the image is so dim that it just appears to do nothing.The digital port is interesting though, but I can't find any references to software.

author: Fraser
author_rank: Super Contributor
timestamp: July 09, 2019, 05:28:14 pm
content: I thought about this overnight and remembered something very important that a very wise friend told me......With a faulty BST camera, monitor the current draw during boot carefully.The BST sensor contains a Peltier module that sets the operating point for the sensor array. The Peltier module draws significant current as it works to get the sensor die to the required temperature. This is seen as a higher current draw at first boot that drops back to the nominal current draw for the camera after a short period of time. If you boot a BST camera and do not see increased current draw, followed by a drop back to nominal, something is wrong with the Peltier module drive. From memory the ARGUS 2 BST camera had an initial current draw from its battery of around 800mA that dropped back to around 450mA. The ARGUS 2 battery is a 12V pack.It would be worth investigating the Peltier module drive behaviour to ensure it is functioning. Loss of temperature setting and stabilisation on a BST sensor is crippling to its performance.Fraser

author: Spirit532
author_rank: Frequent Contributor
timestamp: July 09, 2019, 05:29:44 pm
content: Nope, that's working. Pulls about an amp at startup, then drops to 300mA gradually.

author: Fraser
author_rank: Super Contributor
timestamp: July 09, 2019, 05:36:50 pm
content: Ah, pity, that would have been an easy fixFraser

author: Bill W
author_rank: Super Contributor
timestamp: July 10, 2019, 04:11:32 pm
content: If it is a low vacuum, in 'auto' mode the image should get very noisy. Does it ?I do not recall many BST going to air though.It could be a fault in the auto / manual mode control. You have 4 lines, 2 logic ones to select manual or auto and two that set the manual levels. The controls were meant to be variable resistors across 0V / 5V.I think that digital control was only in the later cores, you have the older 'analog' board.Bill

author: Spirit532
author_rank: Frequent Contributor
timestamp: July 10, 2019, 04:18:56 pm
content: No, it doesn't get noisy in "auto". Nothing changes. That's an interesting point, which means it's most likely not vented to air.Could you by any chance let me know where those 4 lines are? On the card edge connector, or on the gray 80-pin Amphenol? And if so, which pins? PMs are okay.

author: Bill W
author_rank: Super Contributor
timestamp: July 12, 2019, 12:44:10 pm
content: Your power board image shows a MAX520, quad DAC, very slow access not for video.Something must need 4 DC levels........

author: Spirit532
author_rank: Frequent Contributor
timestamp: July 12, 2019, 05:43:06 pm
content: Something must need at least 2 DC levels.I found the "gain" and "level" voltages on that MAX520 - "gain" is non-inverting(going up makes it go up), "level" is inverting - going up makes it go down. Both are present and are full range.I've traced them out to a few pins on the headers, but then they vanish. I couldn't find where they go.Any idea where to go from here? Where are these voltages utilized?

author: Bill W
author_rank: Super Contributor
timestamp: July 13, 2019, 02:14:41 pm
content: So both the DC controls work, but have no effect on the video ?Given that, the other two channels of the MAX520 might be the auto / manual switching for level and gain.We did that on Argus2 & 3Are any controls making the other channels of the DAC change ?0V is manual control, 5V for auto, not sure if a Gen 1 core lets you float it for auto.I would expect the levels from the MAX520 to head fairly direct for the 80 way as they control the DSP card behaviourEqually the levels must end up on an ADC on the DSP board, likely a slow 8 bit serial connected one, not the video one. If you cannot find one, then it could be in the giant ASIC.Are all the pins on the 80-way connecting well to the PCB ? Sometimes they lifted offBill

author: Spirit532
author_rank: Frequent Contributor
timestamp: July 16, 2019, 12:46:42 am
content: Quote from: Bill W on July 13, 2019, 02:14:41 pmLevel has no effect, gain does(overall image brightness).Quote from: Bill W on July 13, 2019, 02:14:41 pmI've identified all four(ish) channels - two are for the gain and level settings, another is for the viewfinder brightness, and the fourth is an unknown voltage that does not vary with anything, but lowering it down to ~0.2V from the ~1.1 it's at with a high value resistor seems to make the UI overlay text dim(no effect on the image).Quote from: Bill W on July 13, 2019, 02:14:41 pmThe level signal goes into the 80 way connector, then it just disappears into the inner layers, right at the connector, which I've gone over with an iron just to make sure.Quote from: Bill W on July 13, 2019, 02:14:41 pmThe only ADC I could find was the TLC1541C, which is only 32ksps. None of the signals seem to go there, or if they do - somehow indirectly.