request: complete ScanPro50 tuning guide - including factory settings

[buffo]

Hey folks!

I've got a problem... A good friend of mine was recently tuning his ScanPro50 scanners using my tutorial. Unfortunately, he got his pots mixed up, so instead of adjusting servo gain, low frequency damping, and high frequency damping, he adjusted the position offset and possibly the zero offset as well. ARGH! Now his scanners are totally hosed...

OK - I'm more than capable of tuning a set of scanners, so I told him I'd do my best to get them adjusted correctly. But I don't know how to tune the other 4 pots on the amp. Those are normally set at the factory and then left alone. And in this case it looks like I'll need to to a complete re-tune on these amps, so I want to be sure I have everything set correctly, including those extra pots that are not normally adjusted when you tune.

So does anyone have a procedure for adjusting Input Scale, Position Offset, Zero Offset, and Position Scale on the SCanPro50 amps? (Actually, I think the last one - position scale - is basically input gain, so I can handle that one, but I need to know what do to with the other 3...)

Adam

[FourDee]

Wel input scale is actually the input gain

You should adjust the position scale (PR2) for a voltage of around 5V on TP3 and TP4 (they are complementary, meaning TP3 will be 0 if TP4 is max and vice versa) when you move the scanners to their extremes.

Before you do this, make sure that you remove jumper JP5 to remove power to the coils

Regarding the other pots, I should check the schematic I have lying around here somewhere.

[buffo]

Thanks for the quick reply!

Wel input scale is actually the input gain

Interesting... The manual I have identifies the Position Scale pot as input gain (which I thought might be incorrect). I agree that input scale certainly makes more sense. Maybe a bad translation from Chinese on my copy?

You should adjust the position scale (PR2) for a voltage of around 5V on TP3 and TP4 (they are complementary, meaning TP3 will be 0 if TP4 is max and vice versa) when you move the scanners to their extremes.
Before you do this, make sure that you remove jumper JP5 to remove power to the coils

Not exactly sure what you mean here. OK, with JP5 removed, look for 5V between tp3 and tp4, but with what signal applied to the input? (Quadrature square wave?) And I'm assuming I'll need to use the 'scope to see this... Also, I'm assuming that the test points are labeled on the amp? (I don't have it in front of me at the moment.)

Regarding the other pots, I should check the schematic I have lying around here somewhere.

You have the schematic for the entire amp? How'd you get that?

Adam

[mixedgas]

Buffo, you might find this interesting reading. Its for the baseline cambridge the chinese like to clone. Note AGC in this schematic is actually the amount of drive to the position sensor leds.
Skywise hosts it for me..

http://www.skywise711.com/lasers/scanner/scanner.html


Steve

[FourDee]

Not exactly sure what you mean here. OK, with JP5 removed, look for 5V between tp3 and tp4, but with what signal applied to the input? (Quadrature square wave?) And I'm assuming I'll need to use the 'scope to see this... Also, I'm assuming that the test points are labeled on the amp? (I don't have it in front of me at the moment.)

Nope, no scope needed, and no input signal

The TP3 and TP4 are outputs from the PD. You just turn the rotor to an extreme and measure the voltage on TP3. Of it is 0V, measure on TP4 or turn the rotor the other way. Then adjust till you have 5V

And I can confirm that the schematic is identical to the CT amp. I just can't find it right now ...

[mixedgas]

Nope, no scope needed, and no input signal

The TP3 and TP4 are outputs from the PD. You just turn the rotor to an extreme and measure the voltage on TP3. Of it is 0V, measure on TP4 or turn the rotor the other way. Then adjust till you have 5V

And I can confirm that the schematic is identical to the CT amp. I just can't find it right now ...

is it identical to 68XX or ct micro amp.??

Steve

[dave]

You have the schematic for the entire amp? How'd you get that?
Adam

Hey Adam,

I have most of the schematic drawn up from one of the new style scan amps. Ill email it to you now..

[dave]

http://www.skywise711.com/lasers/scanner/scanner.html


Steve

is it identical to 68XX or ct micro amp.??

Steve

Very similar to that one Power limiter is a bit different tho, which I think is probably a good thing

[mixedgas]

Very similar to that one Power limiter is a bit different tho, which I think is probably a good thing

The raytheon Power Limiter chip is no longer made. Junktronix has a tube of them, but that is the last source on the planet.

Steve

[buffo]

Thanks to everyone who helped out. I'll reply back here when I've had a chance to give it a try. (Hopefully with good results!)

Adam

[FourDee]

Sonima seems to have a source for the chips, because they are still using them

[mixedgas]

Sonima seems to have a source for the chips, because they are still using them

At the end of life, chip makers offer "lifetime buys" where you can get all the remaining stock of the dies mounted on closeout. I'll bet they did a "lifetime" buy. Or had them cloned. Whats the chip manufacturer on the Sonimas???

Steve

[cfavreau]

Regarding the original thread question. I also have a set of scanners, this time ScanPro40's instead of the 50's. I bought them used off of Ebay from a seller who did not know what they were doing. Every pot had been tweaked and the things were completely out of tune. I tried to get them in tune however I was never really able to get them tuned above 24 kpps. I also had a high frequency oscillation at low scan speeds ~5 kpps.

Until I read this thread I just thought they might be damaged. I tried tuning the position feedback and it fixed the amps. I no longer have the high frequency oscillation at ~5kpps and it was a lot easier to tune the scanners to higher speeds in a much shorter amount of time. I finally got them tuned to almost 30 kpps (only spent about 15 minutes on tuning the pair). The scanners are a lot quieter too.

I used pots PR1 and PR2. As discussed earlier these pots adjust the optical feedback voltages. PR1 adjusts the position offset voltage and PR2 adjusts the position offset size. In order to do this use TP3, TP4, and a ground connection near TP3/TP4 and a multimeter. As mentioned in a previous post be sure to remove JP5 as this removes power/drive to the coils. Once you remove JP5 you can move the scanner's shaft from stop to stop. At one end, TP3 should read near 0V (mine was around 0.5V) and the other end TP3 should read 5V. TP4 should read the exact opposite voltage that TP3 reads. For instance, if TP3 reads 0V then TP4 should read 5V and if TP3 reads 5V then TP4 should read 0V.

The hardest part about making the adjustments is that if PR1 is not correct then it is a bit difficult to get correct. Reading TP3 I simply adjused PR1 until it woul not move the voltage any lower. I recorded that as the low voltage. I then adjusted it until it would not move the voltage any higher. I subtracted tis high voltage from the low voltge and divided it by 2. Then adding this number to the low voltage you get the approximate center voltage. Now just adjust PR1 until you arrive at the center voltage.

Next you will need to read TP3 at the stops. If it does not read close to 0 and 5V then adjust PR2 until the top end reads 5V. Now check TP4 the same way. If TP4 does not read 5V on the top end the you will need to move the Position Offset so that it gets TP4 closer to 5V. Now test TP3 again. It should be off. Adjust PR2 again. Repeat the whole adjust offset, test TP3/TP4, adjust PR2.

That probably all sounds confusing however the point is that you need to center the Position Offset first. Then walk the Position Offset and Position Scale until TP3 and TP4 both read 5V at the ends of the rotor's scan angle.

I think probably having 2 multimeters would help out immensely. I only have one... I suppose I should have gotten my scope out and used it instead.

Anyways I found that this works well. Hope this help out.

[dave]

At the end of life, chip makers offer "lifetime buys" where you can get all the remaining stock of the dies mounted on closeout. I'll bet they did a "lifetime" buy. Or had them cloned. Whats the chip manufacturer on the Sonimas???

Steve

The amps I have here have the raytheon chips. I had to buy a spare one from Sonima, and they were expensive.. Guess they know what they are worth..

[buffo]

Thanks for the tips, cfavreau!

Adam

[cfavreau]

The amps I have here have the raytheon chips. I had to buy a spare one from Sonima, and they were expensive.. Guess they know what they are worth..

I have a few questions about the chips since people are talking about them.

1) Not having a schematic or a data sheet on them what do they do?
2) Should I be concerned about them? Should I get a replacement?
3) Can they be bypassed or is there a substitute that can be made... maybe on an addtional board?

Thanks.

[mixedgas]

I have a few questions about the chips since people are talking about them.

1) Not having a schematic or a data sheet on them what do they do?
2) Should I be concerned about them? Should I get a replacement?
3) Can they be bypassed or is there a substitute that can be made... maybe on an addtional board?

Thanks.

They are used in the coil temperature calculator, CTC, it pulls the input signal to ground if the integrated product of the energy expended in the galvo is too high. It squares the input signal, and feeds a leaky integrator, that is all. If the integrator charges high enough, it biases on a FET across the signal chain and pulls the image size down. If it gets seriously dangerous, your image size suddenly shrinks and the image can distort.

Not all amps have CTCs.

What worries me is I have never seen this happen at SELEM, makes me wonder if the circuit was copied properly.

There is no second source for the part. Kevin Criqui has a tube or two of them, and if you are concerned, just order some from Kevin. They don't pop very often at all. You should not be concerned.
Quite a few vendors who stock discontinued chips have them in stock. If I have to, I know how to make a board that will do what is needed.

I will say this about adjusting the LED current source, keep the current down. It is possible to pop the leds in the sensor with some galvos. If you have to, put a voltmeter across R19(cambridge 6XXX amp) and watch I led as you adjust..


Steve

[cfavreau]

Which one is the LED current? Is that Position Scale? I thought it was just adjusting opamp gain?

If it is the LED current, then I have already ran it up probably too high on one end. It isn't now, just when I was adjusting things I ran the Position Scale up to see what effect it had on TP3 and TP4. I don't recall if I went all the way up though. I do know that TP3 and TP4 can go to over 7V which would mean that the LED can get over 50% brighter? than it should be when properly adjusted.

Does anyone have any factory setup guide or something for these amps?

Thanks!

[mixedgas]

Which one is the LED current? Is that Position Scale? I thought it was just adjusting opamp gain?

If it is the LED current, then I have already ran it up probably too high on one end. It isn't now, just when I was adjusting things I ran the Position Scale up to see what effect it had on TP3 and TP4. I don't recall if I went all the way up though. I do know that TP3 and TP4 can go to over 7V which would mean that the LED can get over 50% brighter? than it should be when properly adjusted.

Does anyone have any factory setup guide or something for these amps?

Thanks!

If you go back and reread the thread, you'll find a link to a old Cambridge manual Skywise hosts for me. Its combined with a LM LSDA22 to make life easier for me..
A schematic is there. And yes, there are 2 pots adjusting the led and one of them is POSITION SCALE. When you set the position sensor up, you are changing the optical power in the galvo sensor. That subsection of the schematic, lower left, that says "AGC OUT AND AGC RETURN"is the led current source. AGC is a left over term from General Scanning's position sensor. It really was a automatic gain control loop. On the GSI RF sensor, this was a must for printing and marking applications. On this Cambridge,and your clone, its just a good current source.

BTW, this cost me probably 550$ to learn, the cost of going to a Laser FX conference and attending the Cambridge factory seminar..

More people should go to conferences, it would really help the industry..



Steve

[buffo]

I agree, Steve.

Unfortunately, conferences aren't as popular as a Lase-off. We learned this at SELEM over the past few years when everyone voted in the forums to have lots of presentations, but when it actually came time to turn off the lasers to listen to the presentations, it was like the school bell ringing at the end of recess. No one wanted to stop playing.

On the other hand, a few people can attend a conference, learn a lot, and then come here to pass on their knowledge. That might be an alternative...

Adam