Chronograph Giving Me Fits

[03lover]

My chronograph is giving me fits and I hope you or some of your friends can come up with some good suggestions. Hopefully, suggestions as to how I can eliminate the problems with me present chronograph rather than, "junk it and get a good one." I have a Pact Chronograph that is about ten years old. It has the light diffusers but works better without them. I also have the printer that goes with the Chronograph.

One problem is with low readings in the 200 to 250fps range. These I found to be created by the cables attached to the bottom of the sky screens shaking in the wind, so I taped the cables to the mounting bar and that eliminated most, but not all of the low readings generated without firing a shot.

The next problem is high readings in the 1200 to 1250fps range. I found these to be caused by muzzle blast. Even when my buddy shoots next to me I get one of the high readings.

Both of these problems are not present all the time and I have been unable to identify the conditions or lack of that may be causing the problems.

I will be contacting Pact again about these problems. The were not very hellpful the last time I contacted them.

Any suggestions will be greatly appreciated.

[GeneT]

The sensors are resistive. So is any kind of break or weak spot in the cables. The problems you describe are consistent with a cable going bad, and the age of the chrono is consistent as well. If you're at all electrically handy, I'd replace the cables - just be careful not to move anything around in the sensor housing. (you can get cord and plugs at Radio Shack, or elsewhere [Edit: you should be able to re-use the old plugs]). Alternately you can get new sensors from Pact, for I think $30. I doubt there's anything wrong with the 'brain' box - and that's the good news.

GsT

[fredj338]

The older PAct chronos have really poor screens. Mine would be all over the place for readings in qall kinds of light. I finally shelved it & bought the Oehler. Try getting Pact to replace the screens.

[AZ-Stew]

I'm guessing you have a loose connection between the cables and sensors. The slightest movement (wind or muzzle blast) causes a momentary disconnect, triggering the timer.

As noted, if you're electrically savvy, open up the box and re-solder all the connections having to do with the sensors and cables. DO NOT do this with one of the old Weller soldering guns. They work for radiators and plumbing but are ABSOLUTELY no good for electronics. They get too hot and their tips are far too large. If you don't have the right tools, find someone who does and knows how to use them. A local Ham Radio operator would be a good choice.

Another option is to trade it in to Chrony. They give a substantial discount for trade ins.

There are a couple of other recent threads floating around the forum regarding chrono setup and use. Do a search. There's much good info in them.

Regards,

Stew

[303Guy]

03lover, you didn't mention whether this is a more recent developement or whether this chrono has always done this. Responding to muzzle blast sound like a vibration thing and the chrono is measuring the speed of sound from and angled source (hence the higher than sonic velocity reading). It could be 'dry joints' in the soldering but for both triggers to be simutaneously affect is a bit coincidental. Still, it could happen. Does the machine give these false readings if you tap the cables or the plugs? And if you tap on the screens?

[Whitespider]

The problem could be the "brain" box, but I would doubt it, my PACT model #1 is about 30-years old now and still works perfectly. I wouldn't think the problem is the actual light sensors either, there isn't anything overly complicated or super high-tech about sky screens. It sounds like you have one or two issues related to vibration and maybe one related to the light getting to the sensor eye.

The first thing I'd do is clean the connections where the cables plug into the "brain" box. Clean the plugs on the end of the cables with alcohol (or electrical contact cleaner) and fine steel wool. You can open the "brain" and remove the covers from the sockets to get at them, but cotton swabs dipped in alcohol (or cleaner) and shoved in and out of the sockets should clean them up. Afterwords, a thin coating of dialectic grease on the plugs should help also.

The sensor eyes themselves are photo-transistors. The wires are simple coaxial cable with the center conductor soldered to the "collector" of the transistor and the shield soldered to the "emitter" side. It's possible that these solder connections have broken, or maybe the wire is broken somewhere close to the sensor housing. It's also possible that over time the stress has bent the wires/connections inside the housings so they occasionally short. If you take the four screws out of the housings you can "split" open. Inside will be a couple clear plastic lenses you can lift out and clean (make sure you put them back with the "up" side up). Check the solder connections on the little eye and also check the wires to make sure they aren't broken (you may have to shorten and strip the wires back a tiny bit and re-solder). You can also test the wires for continuity (the center conductor goes to the tip of the plug). Have someone wiggle test the wires as you check continuity. When you reassemble make sure the sensor eye sits squarely in the little recess that holds it tight and aligned. Also make sure that the wires are in the stress relief slot and there isn't any chance they can short across.

[03lover]

303Guy,

The chronograph is a 1987 Pact. Wow how time flys. I thought it was only about ten years old.

To answer your question, NO, it didn't always do this. I did have problems with missed readings off and on from the start and that was usually due to poor sky conditions.

I would get so frustrated with the darn chronograph that it sometimes sat for several years. Recently I have been doing a lot of load developement and started using it again. If I can't find a reasonable fix to these problems, this chronograph will be retired for good. Too bad, all the years I have struggled with this thing, I never shot it. Now I am getting the urge to put a bullet through it.

Whitespider,

Your suggestion about the cables is something worth checking out. Also, there has been a number of forum threads indicating the brain box can be a problem with muzzle blast, even when located behind the shooter. Pact has suggested this also. The problem seems to be more so with the Pact chronographs.

I plan to take a few hours in a couple of days and start checking out what has been suggested here. Hopefully I will be able to identify the source of the problem

[Mr Peabody]

I too use a 1987 Model One Pact. I did have fits with it until I bought the new sensors and the little shades that fit on them. What do you use to mount your bar out in front of you. I use a large and stable tripod and try to put it at least 10 foot in front of me. The cables hang straight down from the bar and run out on the ground till they come up on the table where I'm shooting from. Cloudy days are best. Days with big fluffy clouds drifting by are the worst. This thing senses the bullets shadow; direct overhead light is a killer too. You can turn these sensors at a right angle to your line of fire if the sun is overhead and they'll work just fine if the bullet passes by the opening for each sensor. I'd like to have a longer spacing than the 24 inches they're programmed. It might work more accurately with velocity's over 3000fps. If you decide to get rid of it, holler out. I'd like another.

[jmh54738]

I agree with Mr. Peabody relative to the cable placement, it is important as PACT told me. An old battery can make readings crazy. My unit has a large battery which is soldered in and needs replacement about every 5 years.

[03lover]

Mr Peabody,

I also use a very heavy duty camera tripod and set it out as far as the cables permit.

Your suggestion to buy new sensors has come up on another forum. Also, cleaning the plug ends of the cables and the sockets may help as could checking the solder joints on the sensors.

I think I have enough suggestions that make sense when considering the types of problems I am having, to set up the chronograph tomorrow and do some testing to see if I can isolate the source of these problems.

Then I will call Pact to see how much they can help with the limited life time warranty the chronograph is suppose to have.

I would buy a different chronograph in a heart beat if I wouldn't be scrapping my HP printer that will work only with my Pact chronograph. The printer cost almost $90.00 back in 1989 and it wouldn't be worth $0.02 without the Pact I have.

[03lover]

Chronograph Problems

The day is June 30th 2010, a bright sun shiny day 75 degrees and perfect for some load testing.

I set up my Pact Model 1 chronograph I had purchased in 1990. I have been having problems with this chronograph picking up readings when my shooting buddy fired his handgun 4ft to my right. I had tried covering the sensor cables, the brain box and whatever else the Pack people had told me to no avail.

True the bad nature of this Pact chronograph, it started off picking up every shot my buddy took. I decided to stand a 2’ x 6’ by 2” thick piece of Styrofoam in front of the two sensors, actually resting against the one nearest me. My buddy continued shooting and I got no more readings caused by his muzzle blast or shock wave.

Obviously, this is no fix to the problem. I even tried cutting the foam down to a height that would allow the use of the chronograph, but the problem came back. My buddy’s shooting caused readings and my own shooting cause readings in the 1225 fps range, which were way too high for the cast bullet load.

I called Pact knowing I had never received a satisfactory answer from them in the past. I described in detail the tests I had conducted today. Pat at Pact suggested turn the sensors 90 degrees to one side and fire in front of them. Also, I could try covering the brain box with something to prevent the shock wave from hitting it. My answer to that was, “You were not listening to me when I described the tests I had done earlier this afternoon. Protecting the sensors from the blast eliminated the problem. It is the sensors that are the problem, not which way the sensors are pointed or where the brain box is, which was behind me.”

Pat had no more suggestions, so I hung up and started considering my options.

Since I have a Pact chronograph purchased with an optional HP printer, both of which are no longer available, buying another manufacturers chronograph would mean both my printer and Pact chronograph are useless junk. There is nothing made today that works with the HP printer I have.

NO. 1 option appears to be – Buy new sensors and hope for the best.

NO. 2 option may be – junk what I have and buy something else, BUT WHAT? Is there a chronograph out there that provides most of the data my Pact does and print it out, that doesn’t have any problems or cost an arm and a leg?

I am not at all happy with the people at Pact. They really know little about their product and less about how to fix a problem. I asked if they maintained a file on problems users of their chronograph have had and what was done to fix them? They have no such file. You would think if the sensors have been a problem for many years in the past, perhaps they are still a problem. No suggestion that Pact had worked out a problem of sensors going bad.

Other than buying new sensors hoping that will fix my problem, I AM ALL THROUGH WITH PACT.

Guys, what is one or more of the trouble free chronographs that are on the market now?

[JSH]

Almost every time I see some one set up a chrono at the club, they set the thing to close to the bench or muzzle. They then get goofy readings that go all over the place and then it is an equipment failure. What difference does it make if the reading is at the muzzle or 20 feet away. You still have a reading and numbers to go by.
I have a piece of cord that I use to place my chrono at the range.
Try moving your chrono out and see what results you get.
jeff

[03lover]

JSH,

I always place the sensor bar as far out as the cables will permit.

[Mr Peabody]

03 Lover;
You sure got me shakin my head. I've had people shoot along side of me while I clock a load and never had any trouble for it.
For the heck of it, take your large piece of styrafoam and place it as you said. In front of the nearest sensor, cut out a triangle somewhat smaller than your sunshades and shoot thru the hole. If it works then shock waves might be what's causing your problems; which I think means something is loose out in front of you.
Good Luck

[fourarmed]

My original Pact (PC) packed it in, and I called them. The guy said "Send it to us with five bucks." In a couple of weeks they sent me back a complete reconditioned Model 1 that has worked great ever since. Maybe they don't do that any more.