Radar detector teardown and look inside. - Page 1
Forum section: electronics / repair

author: TheEnd
author_rank: Contributor
timestamp: August 18, 2015, 05:13:01 pm
content: Many years ago, I bought a cheap Beltronics Euro 550 Radar/Laser detector.They aren't of great value these days, GPS based systems, the Mk1 eyeball and common sense do a better job, but it's an interesting bit of kit non the less.Firstly in use, they don't do a hell of a lot in the UK, Laser detection would have to rely on a very lucky bit of scattering from someone else's car, if you get targeted, your speed would be on the gun's screen before you have a chance to react.The radar detector similarly warns you of Mercedes with radar based cruise control and automatic doors on shops, so it's mainly false alarms all day.Anyway, this is what it would normally look like-and this is what it looks like with the lid off-The large metal can is the main waveguide and radar detector.In the second pic, you can see a small cut out in the can which is where one of the laser detector sits, and the lightguide can be seen on the plastic shell.There are two sensors inside, for front and rear detection.This is the gorgeous LED dot matrix display-and this is the issue I was facing which would appear after maybe 30mins of On-time, and now comes on instantly.?LO3 CAL apparently relates to Local Oscillator 3 calibration.If it has to respond to certain radio frequency bands, it's going to need some sort of reference.My first idea was to open it up, look for any crystals and replace them and see what happens.This is the bottom of the unit-There's a 4Mbit TSOP SPI flash chip (Datasheethttp://www.atmel.com/Images/doc3443.pdf)and a Motorola MC68HC908GP32 series microprocessor. The pads by the side look to be BDM pads and the datasheet confirms MISO MOSI SCK etcDatasheet -http://cache.freescale.com/files/microcontrollers/doc/data_sheet/MC68HC908GP32.pdf)Flipping it over and removing the radar can shows the top side of the boardThere's only one main 4MHz crystal for the processor visible, and since the error was for LO3, I would have expected 3 oscillators at least! The laser detection photodiodes can be seen in the top left of the PCB.Time to delve into the radar module-I can see a small device in the middle which I'm assuming is a Ceramic resonator, only a GE marking, so no info on what it is resonating at.The other large device is marked SC 9046 which isn't enough for a google hit. It appears to be metallic which two "corridors" running though it. There is a trimmer, but I'm smart enough to leave those well alone for now.Here we have it again with some incidental light to get some component numbers-There's an ON semiconductor VHC 02 PGYZ which all I can get is a very high speed CMOS.An LMX2325 - "PLLatinum 2.5 GHz Frequency Synthesizer for RF Personal Communications"and a Philips SA614AD - "The SA614A is an improved monolithic low-power FM IF systemincorporating two limiting intermediate frequency amplifiers"Flipping it over again and opening the top cover and waveguide reveals this-There's an 10 pin header with a curious semi-transparent disc stuck on top of it. I'd assume it is some sort of "programmed/calibrated, don't touch" marker as there isn't anything interesting underneath.There are (on both sides) quite a few splayed "antenna" pads, and some unusual round components, marked C and one with a G with X arranged legs.Top view- higher res-Getting into radar based stuff is well outside of my field, but as there wasn't much more I could see or do, it went back together, and hey presto -He's back up and running for now at least!So, there we go, a quick look inside a combined laser/radar detector, which a fancy tiny LED matrix and since I didn't mention it earlier, it talks to you too!

author: Gyro
author_rank: Super Contributor
timestamp: August 18, 2015, 05:58:43 pm
content: Wow, that a hell of a lot of complexity for a simple radar detectorI used to be involved with doppler microwave traffic detectors for traffic control and there way way less in those!Thanks for sharing

author: Fraser
author_rank: Super Contributor
timestamp: August 18, 2015, 05:59:00 pm
content: The RF section is nice quality. Far better than cheap Radar detectors that I have worked on.Aurora

author: cozza
author_rank: Regular Contributor
timestamp: August 19, 2015, 02:04:30 am
content: I had a similar unit (Beltronics V940) and the surface mount electrolytics were high ESR. Fault symptom was locking up with laser detection false alarm.Not surprising given the extremes of temperature inside a vehicle.

author: tautech
author_rank: Super Contributor
timestamp: August 19, 2015, 08:39:10 am
content: Quote from: cozza on August 19, 2015, 02:04:30 amExactly.Possibly corrosion of the connecting headers may have caused the OP's headaches?My son dropped his $700 Escort unit and a SOT-23 bipolar that was mounted very close to a through hole plastic stand-off took the impact and broke in half.Luckily we could still read the SMD code and soldered an equivalent in it's place and still going to this day 10+ years later.