8500 X50 Self Calibration Failure: Service Required

I have had this detector 2 years and the self calibration has been bombing out for the past 6 months. I have no interest in sending it in. Does anyone know the fix for the detector? I may break it open and fix it if I know which direction to go inside; otherwise, I'll likely trash it and buy another, different brand. I have read some on the V-1. I hard wired the 8500 detector about 6 months after purchasing. Is there any truth to hardwiring causing this problem or is it just a defective detector? Thanks.

It has nothing to do with hard wiring. It has more to do with heat and age. It's probably not something you can fix yourself since Service Required messages usually end up needing a replacement antenna.

If you trash it, you can always send it to me in Florida. :D Of course I'll pay the shipping.

Try resetting it by press the mute and the top buttons on top holding it up and power the unit on. See what happens.

I'll try resetting it. I don't recall the book mentioning anything about resetting the detector. I wonder what is happening to the antenna as far as heat damage. To self calibrate, how does the anttenna come into play?

I will likely open it up to see if there is any obvious heat damage that can be repaired. I always leave the detector in the car, although not on the dash. I thought someone may know the actual fix because from what I read on this board, many have the same problem.

Smith1000,
The antenna is made of Aluminum which expands and contracts
in Hot and Cold weather. If left in the car during extremes you
will see this happen to the detector faster. I've had my X50 for
almost 4 years now and have never had a Self Cal message.
I make it a point to bring the detector in with me most of the
time when I can.

Just curious, do you leave your detector in the window
in the direct sunlight? If so, that's what caused it. If
not, could just be high temps in the car during the summer.

I'd rule out a bad unit, you've had it to long for it to be
defective.

how bad is it to leave it in if it's right behind the tint strip. no sunlight affects. just the temperature sways during winter between really cold and moderate and summer cooking of the cabin.

or if one's better than the other? leave it in the car during the winter but take it in on hot summer days if the windows aren't down?

I remove the unit from the window when I leave the car; however, there have been times I have left the unit in the car during the day. This has happened on weekends when home.

Sounds like I will likely find a broken or separated antenna within the unit. If so, I may be able to fix that fairly easily. I'll take a look and see what it has going on inside. Possiby, the antenna can be allowed some slack to expand and contract freely. Based on the size of the unit, there can't be a whole lot on the inside. Thanks.

Quote:

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Originally Posted by Orbital75

Smith1000,
The antenna is made of Aluminum which expands and contracts
in Hot and Cold weather. If left in the car during extremes you
will see this happen to the detector faster. I've had my X50 for
almost 4 years now and have never had a Self Cal message.
I make it a point to bring the detector in with me most of the
time when I can.

Just curious, do you leave your detector in the window
in the direct sunlight? If so, that's what caused it. If
not, could just be high temps in the car during the summer.

I'd rule out a bad unit, you've had it to long for it to be
defective.

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I don't think it has anything to do with expanding/contracting aluminum. ...just transistors operating at their maximum operating temperature for too long, and deteriorating at an accelerated rate.

I also think variance in transistor quality accounts for the varying experience WRT to self cal messages and heat tolerance. I also think this explains why some X50s are unbelievable, and others more "human". My one blue X50 thinks it's a V1.

The X50's horn does not contain a separate LO board. Instead the LO circuitry is part of the main board under the horn. The expanding and contracting aluminum horn relative to the circuit board can cause the horn-to-board screws to eventually become slightly loose, resulting in poor grounding of the horn and/or the loss of a tight RF seal around the LO electronics on the circuit board which are enclosed by the horn.

Since it is so easy to remove the X50's bottom cover and check that the horn-to-board screws are tight, this really should be checked first before sending in an X50 for service -- especially if the X50 is out of warranty. After checking the screws and hopefully finding one or more of them slightly loose, be sure to hold down the appropriate buttons to factory reset the X50 upon the first power-up after checking the screws. With luck, the X50 will then complete its power-up sequence with no self cal or service required message. :)

This is great information. I snugged up the horn to board screws. They seemed tight enough already (enough for grounding I would think), but they did turn slightly. I also snugged up the horn screws from the topside. One of those screws, a flat, inset screw was loose. The topside screws only hold the horn together tight.

I live on a gravel road and have about 3-4 miles to go to the highway. Screws coming loose has been a problem in the past. I had an old laptop that would drop screws. The vibration in the vehicle works things loose.

I reset accordingly and have it in the house now and there has been no self calibration failure so far. It did not go into the self calibration mode following the reset; however, it does not self calibrate every time, so it may or may not be fixed. I'll see how it does. Thanks.

I have also learned about self cal the hard way. My older VW's battery was very weak and as a result would throw self cals on perfectly good detectors.

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Originally Posted by Smith1000

This is great information. I snugged up the horn to board screws. They seemed tight enough already (enough for grounding I would think), but they did turn slightly. I also snugged up the horn screws from the topside. One of those screws, a flat, inset screw was loose. The topside screws only hold the horn together tight.

I live on a gravel road and have about 3-4 miles to go to the highway. Screws coming loose has been a problem in the past. I had an old laptop that would drop screws. The vibration in the vehicle works things loose.

I reset accordingly and have it in the house now and there has been no self calibration failure so far. It did not go into the self calibration mode following the reset; however, it does not self calibrate every time, so it may or may not be fixed. I'll see how it does. Thanks.

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I was hoping that this would work. If you don't get any self cal messages after a week or two of use, then you might want to dip the tip of each screw, each one removed one at a time, in contact cement and then reinstall each screw. This should permanently resolve the self cal problems since the screws won't be able to easily work loose in the future. Unfortunately contact cement dries much more quickly than ThreeBond, so you will likely have to create several puddles of contact cement while you proceed to dip each screw in the contact cement. You can use some isopropyl alcohol to slow the contact cement's drying process though!

Not one self calibration message today all of the way to work and back. Does the loose connection cause the self calibration? I presumed the detector would automatically self calibrate following a certain number of start-ups as part of its regular processing. My thought was, if the self calibration failed, it would again try to self calibrate another 1 or 2 restarts.

I am curious about the self calibration process. Is it an internal calibration or does the detector communicate externally (doubtful)? From what I recall, when I first started receiving the self calibration message, it would complete the calibration and resume normal operation. At some point later on, it would fail and the service required message would result. I would restart the detector and it may or may not work properly. Very soon, it would again get the service required message.

Would loc-tite work on those screws? Thanks.

Quote:

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Originally Posted by Smith1000

Not one self calibration message today all of the way to work and back. Does the loose connection cause the self calibration? I presumed the detector would automatically self calibrate following a certain number of start-ups as part of its regular processing. My thought was, if the self calibration failed, it would again try to self calibrate another 1 or 2 restarts.

I am curious about the self calibration process. Is it an internal calibration or does the detector communicate externally (doubtful)? From what I recall, when I first started receiving the self calibration message, it would complete the calibration and resume normal operation. At some point later on, it would fail and the service required message would result. I would restart the detector and it may or may not work properly. Very soon, it would again get the service required message.

Would loc-tite work on those screws? Thanks.

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My theory is that the slightly loose screws cause a flaky ground connection for the horn, and that this somehow interferes with the self calibration process.

Belscort radar detector models self calibrate upon every power-up and then periodically thereafter while powered on in order to correct for temperature induced frequency drift. The self calibration process is an internal one which basically involves a process of precisely adjusting the voltage to the local oscillators to make the local oscillators produce the correct frequencies relative to a single on-board crystal reference frequency. The circuitry for the on-board crystal is temperature compensated.

Anyway, it sounds like your self calibration and service required issues are resolved. Use your RD for several days more and if all is good, then open it back up again and secure the screws with contact cement.

I would NOT use loc-tite on the screws! The screws are tiny and loc-tite is extremely strong stuff! You probably will never be able to get the screws out again without completely stripping the heads. Contact cement, once cured for a day or two, has more than enough holding power yet will allow the screws to be removed if need be for servicing in the future. Just get a small amount of contact cement on the bottom third of each screw. That will be more than enough to prevent the screws from working loose in the future. You could dab some contact cement atop each screw head and onto the surrounding circuit board to secure each screw, but that would look really tacky and could pull off the silicone overcoat on the circuit board. Again, a bit of contact cement on the bottom part of each screw would be the best method and will do the needed job of preventing these screws from working loose.

Quote:

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Originally Posted by MEM-TEK

The circuitry for the on-board crystal is temperature compensated.

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How does that work?

Quote:

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Originally Posted by aradarnut

Quote:

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Originally Posted by MEM-TEK

The circuitry for the on-board crystal is temperature compensated.

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How does that work?

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Maybe I should have said , "The circuitry for the on-board crystal is very stable with regards to ambient temperature."

Heck, I am not really sure if Belscort is using additional circuitry in conjunction with the crystal to assure a very accurate reference frequency regardless of ambient temperature. It may be that the reference frequency from the crystal is stable enough throughout the specified operating temperature range of their radar detectors that an additional temperature compensation circuit is not needed. This really is a question for Jimbonzzz, the Professor, since he has delved into the operation of radar detectors in general considerably more deeply than I have.

A crystal oscillator by nature is very stable over temperature changes. In the X50, the 1st LO is calibrated by examining mixer products which result from mixing the first LO with the 2nd LO. Since the 2nd LO is crystal referenced, the 1st LO can be accurately calibrated.

Interesting, thanks for your inputs. How do police dash units maintain accuracy after baking in the sun? Similiar techniques?

Quote:

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Originally Posted by Smith1000

Not one self calibration message today all of the way to work and back...

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Hi Smith1000,

How is your X50 doing now after a few days? I am dying to know whether or not it is still giving you self calibration error messages!

--Michael

Michael,
It's doing great. Not one self-calibration failure since tightening the screws and resetting. It starts up normally and has been remarkably quiet all week. It only alerted a few times this week, KA and K. The highway patrol around here uses KA and the county is K. There has been a lot of rain here this past week which translates into fewer to none running radar.

I believe it is working fine now, similar to its behavior when new. It is in highway mode and is detecing about a mile. The county will run his K constantly, so it is easy to tell as the signal becomes stronger. Many thanks!

If and when the problem occurs again, I will put some contact cement on the screws.

Hi Guys, another newbie here. So glad that I found this site. I bought two new RX65s in May '07 through cardomain.com while I was travelling in the US (3mths in an RV - sweet). Didn't get it until just before I came home to New Zealand so no US use at all. I gave one to a mate and his is fine but my one has started doing the selfcal - service required thing. It is a version 6.1 manufactored 5th week of '07.

I live in an area where it gets nice and cold in winter, (had 10 nights in a row of minus 11 celcius, not sure what that is in farenheit but it's well below freezing) then the summers get up to around 40 deg C (100ish). My mate lives in a more temperant area. I'm thinking that my problems are probably heat/cold related but have a question.

If I open up the case to tighten screws, will that void the warranty? I'm not sure if it will be covered anyway as I have lost the invoice and I'm not sure if cardomain.com are authorised resellers (they said they were).

Other than the selfcal problem it has been a great detector. I am a soon to be retired cop of 20 years so am very familiar with the radars/lasers etc and this detector works better than the V1 in my opinion. It has very similar detection distances but the tech mode sets it apart.

I have disabled X and K as they are not used in NZ anymore and the tech display allows me to instantly know if the threat is a cop or just leakage from the cheap detector that just passed me.

I look forward to some interesting discussions with you all.

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Originally Posted by robster66

Hi Guys, another newbie here. So glad that I found this site. I bought two new RX65s in May '07 through cardomain.com while I was travelling in the US (3mths in an RV - sweet). Didn't get it until just before I came home to New Zealand so no US use at all. I gave one to a mate and his is fine but my one has started doing the selfcal - service required thing. It is a version 6.1 manufactored 5th week of '07.

I live in an area where it gets nice and cold in winter, (had 10 nights in a row of minus 11 celcius, not sure what that is in farenheit but it's well below freezing) then the summers get up to around 40 deg C (100ish). My mate lives in a more temperant area. I'm thinking that my problems are probably heat/cold related but have a question.

If I open up the case to tighten screws, will that void the warranty? I'm not sure if it will be covered anyway as I have lost the invoice and I'm not sure if cardomain.com are authorised resellers (they said they were).

Other than the selfcal problem it has been a great detector. I am a soon to be retired cop of 20 years so am very familiar with the radars/lasers etc and this detector works better than the V1 in my opinion. It has very similar detection distances but the tech mode sets it apart.

I have disabled X and K as they are not used in NZ anymore and the tech display allows me to instantly know if the threat is a cop or just leakage from the cheap detector that just passed me.

I look forward to some interesting discussions with you all.

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Further to above, I have confirmed that opening the case will void the warranty, I guess that is why one of the screws is under the serial number sticker (so they can tell). Anyway, the good news is I got a replacement invoice and although Bel didn't reply to emails, I finally managed to get them on the phone and they will repair it under warranty and even send it back to NZ for free. Lets hope it will be all go after that.