Blaupunkt FM reception driving me nuts! - PeachParts Mercedes-Benz Forum

donbryce · #1 12-12-2003, 09:05 AM

I bought a Blaupunkt Denver CD player on EBay about a year ago. It looks great in the dash of my '85 30SE, which is 90% of why I got it. My old 450SE had a Blau cassette, and the tuner in it was excellent, so I figured...wrong, big time! This piece of junk has an intermitent squelch-like sound (like you get on CB radio) and a lot of sibbilant (sssssss) interference on FM. It does vary with the driving location, but happens on all stations, all FM bands, and no amount of fiddling with the tuning gets rid of it.

I have tried adding an antenna booster (some help, but it's still there), changing the antenna to the original Hirschmann (new mast, still no change), and looked for a screw to adjust the 'trim' (there is none).

Can anyone offer a theory on what is wrong, other than the unit's tuner must be bad? I love the looks of this thing, it plays CD's flawlessly, but all I listen to 99% of the time is 3 FM stations. I'm seriously considering replacing it, but now I'm gun-shy of anything that isn't available locally (Pioneer, Kenwood, etc.) or designed for the North American market. I noticed a post from someone who is having trouble with AM reception with his Becker Audio 10. We're talking high $$ stuff that won't tune in what a $99.00 Koss can do. Is there something fundamentally different about European AM/FM vs N. American?

tecqboy · #2 12-13-2003, 09:06 PM

Did you get a Blaupunkt designed for European reception? The FM bands vary for different parts of Europe ( and the world ) and are not always the same as in the US. Also, USA FM uses a different amount of pre-equalization in transmission. It is more than Europe and would make a European radio sound more sibilant. US FM is spaced at 100Khz and is offset from Canadian FM by one "channel". US FM are assigned odd channels 94.5MHz, 97.3MHz etc. In Canada even numbers are used 94.6 Mhz 97.4MHz etc. US and Canada FM both use 75KHz modulation index. There is no "trim" on electronically tuned radios and on old radios it was only for the top of the AM band. So, to work properly in the USA, a radio must be specifically designed to work there. I have a Blaupunkt MD in my SL and it has the "digi tuner" front end. I have never owned a better FM reception tuner in a car. But I almost never use the tuner; it only gets commercials. I've 35 years experience as a commercial broadcast radio / television engineer. I just looked at your post again and see that you are indeed in Canada. Check you owners manual and see if there is a "secret" menu to set the radio for Canada. Your AM radio is on 9khz spacing too. ( 10 khz is US standard. )

donbryce · #3 12-15-2003, 08:30 AM

THANK YOU!! This is indeed the most informative response yet to this vexing issue. Unfortunately, since I got this on EBay, and it came without a manual, I may never be certain of it's origins. The previous owner did live in the U.S., though, so I downloaded the US manual from the web. I've checked this manual several times, and there is nothing in there on setting/resetting the tuner. Since the car is now in storage for winter, I'll pull the unit and look more closely at it. Do you know if there is anything I should look for to identify whether it was designed for US or european use?

Also, I could try some of the other FM bands on it and see if tuning makes any difference, but I have tried this in the car and couldn't detect any better reception on the 3 'bands' which the US manual identifies (FM1, FM2, FM3/FMT). The manual shows the tuning range as 87.5 - 107.9MHz, intermediate frequency 10.7 MHz. This is in the on-line manual, though, which may or may not match the unit.

tecqboy · #4 12-15-2003, 11:36 AM

Those are not different FM bands. They are 3 sets of pre-set groups. A way the arrange favorite stations. FMT stands for FM Travel. My radio is Dallas RMD 169 US. It has settings for USA LATIN and Europe. The manual says press "DSC" and select TUNER. End / store settings press "DSC" again. That's clear as mud to me. I don't have the radio available to try it either. My car is also in storage away from the salt. The manual says nothing about Canada. In the spec section the Tuner is listed as US FM 200 KHz. Which makes sense as US FM is on 200 KHz spacing at odd numbers. Try operating your radio on FM and notice if it stops at odd , even, or both FM frequencies. If it stops at even or both, then it should work OK for Canada stations. Heck, what to people do who live near boarders?

donbryce · #5 01-03-2004, 12:10 PM

I have 2 favorite FM stations. These are preset to the frequencies 105.3 and 106.9. These are local Canadian, but 'odd' numbers, as you had suspected for a US market tuner. If I do a manual tuning, the displayed frequencies jump 105.1 > 105.3 > 105.5, and 106.5 > 106.7 > 106.9. This, I presume, verifies that the tuner is set up for the US market, as you noted, since the stop points are odd numders.

But I checked and the correct frequency for each station is indeed 106.9 and 105.3. This doesn't agree with your assignment of odd numbers to US and evens to Canadian stations, does it?

What do you suppose is going on here? Should the tuner 'jump' in even increments (105.2 > 105.4 > 105.6), or should it just go up and down regardless (105.1 > 105.2 > 105.3 > etc.)? Should I be able to tune it to 105.2 or 105.4 to get proper reception of 105.3?

#6 01-06-2004, 03:57 PM

You can have a loose solder joint for the antenna onto the circuit board, failing preamp(though I doubt it), moisture in your antenna cable, or bad connection at the antenna itself. A few things to try: check the radio's settings for local/distant receiver setting(s); try the radio in another car; pull the radio and get DC power to it and try an external antenna. Basically you've got to troubleshoot for yourself. Oh, and you can also get the model # off the radio and check it's specs on the FCC's website.

donbryce · #7 01-06-2004, 08:37 PM

Good suggestions all. The local/distant setting doesn't help, though, and I'm confident the antenna connection is good as I recently overhauled the unit (new mast, grommet, etc.). However, it was doing this prior to my overhaul too, so at least I know I didn't create the prblem. I will check the cable itself though, as that's one item I haven't checked. I'll look into the FCC specs too. Thanks.

ctaylor738 · #8 08-02-2004, 07:11 PM

How did this turn out? I have the same problem with the Blaupunkt Orlando (CM127) in my 280SL. It is a euro car.

Could I have a problem with compatibility in my antenna or cable?

Thanks.

donbryce · #9 08-03-2004, 09:03 AM

Well, I tried connecting to a spare antenna and it still wouldn't tune precisely. I also tried a signal amplifier, no change. I figured in the end that it might be the location I'm in, or possibly a defect in the unit's tuner. No way to really tell, and not cost-effective to have it checked. I moved on to a higher end Blaupunkt, which tunes perfectly, but it does have a different tuner system too, digitally improved I think. This is no help to you, I guess, except that my old Blaupunkt cassette unit tuned just fine, so it's 1 out of 3 that didn't. I don't know if the old cassette had the same tuner as the Denver, but it was older so maybe they just have problems with the tuner in the Denver and Orlando series.