• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Marantz 2275 - no stereo FM

alignment tools -- assuming I'm stupid/desperate enough to try some manual fiddling on my FM boards...

would either one of these alignment tool sets handle what's needed on a Marantz 2275?

Aven 13016
Philmore 63-910
 
rBuckner said:
Correct! Smaller/lesser fins are for the FM.

On the 2230 you could sub the 2230's IF board output into the 2275's P300 input with a long enough piece of coax cable. That would narrow it down to the P300 board. Likewise, further back the tuner front end can be subbed into the 2275 but I believe you had good meter movement indicating the front end is strong. Now someone could have screwed with the IF can in that front end and got it out of whack!

On both I'd recommend disconnecting the 2230 cable end, don't leave it in place and just tack the "jumper" cable on.
Click to expand...
I'm (reluctantly) considering bringing in my 2230 receiver into this... with this idea to feed the P300 MPX board on my 2275 with a "known good" signal from the 2230 (which does get stereo FM)... and if I still don't get stereo FM, then it must be something wrong with my P300 board, not further upstream

studying my 2230 schematic, it seems that the signal leaving the P200 (IF Amplifier) does NOT go directly into the P300 board -- but rather to the P500 (FM Detector) and P550 (FM Muting) boards... only after those boards, does the the signal go into P300... very confusing, lots of lines on that schematic!

Q1: seems that the main input into P300 (on the 2230) is at pin J301... is that correct?... if so, should I trace the wire that's attached to J301 back upstream, and then tap out of my 2230 from that point?... from the schematic, that point seems to be J560 (at R563), which is on the P550 (Muting) board

Q2: where do I connect into my 2275's P300 input?... I think it's also J301

Q3: need confirmation that the connection is made with a single wire only, and that it must be coax? (and can I use a piece of "cable TV" coax cable)

Q4: do I have to disconnect the wire currently on J301 on my 2275?... it's wire wrapped... (I'm guessing yes, because otherwise I'll have incoming signals from both my 2275 and 2230 at the same time)
 
Last edited:
ssouci said:
I'm (reluctantly) considering bringing in my 2230 receiver into this... with this idea to feed the P300 MPX board on my 2275 with a "known good" signal from the 2230 (which does get stereo FM)... and if I still don't get stereo FM, then it must be something wrong with my P300 board, not further upstream

studying my 2230 schematic, it seems that the signal leaving the P200 (IF Amplifier) does NOT go directly into the P300 board -- but rather to the P500 (FM Detector) and P550 (FM Muting) boards... only after those boards, does the the signal go into P300... very confusing, lots of lines on that schematic!

Q1: seems that the main input into P300 (on the 2230) is at pin J301... is that correct?... if so, should I trace the wire that's attached to J301 back upstream, and then tap out of my 2230 from that point?... from the schematic, that point seems to be J560 (at R563), which is on the P550 (Muting) board

Q2: where do I connect into my 2275's P300 input?... I think it's also J301

Q3: need confirmation that the connection is made with a single wire only, and that it must be coax? (and can I use a piece of "cable TV" coax cable)

Q4: do I have to disconnect the wire currently on J301 on my 2275?... it's wire wrapped... (I'm guessing yes, because otherwise I'll have incoming signals from both my 2275 and 2230 at the same time)
Click to expand...
Good way to narrow it down, if the signals are the same levels. Very much worth a try.

Ans.1: J301 is the input on the 2230, and comes from J560 which should be disconnected there at J560. Check that out with a meter to be sure.
Ans.2: Also correct and it must also be disconnected.
Ans.3: A single conductor, best in the form of a coax. A single wire may work, but a ground would have to be run and the "hot" wire would be unshielded. I wouldn't bother and that TV coax should work, do connect those grounds at both ends. You don't need to unhook the source end ground at the 2230 nor the destination end in the 2275. Just tack solder the coax shields to those locations.

That noise on the video at the "108" end may be from an LED lamp nearby and possibly any wireless / WiFi signal nearby. I do find it interesting that the meter reads so high when tuned all the way to the left. Is there an adjustment for meter level and if so, was it adjusted? If so, the high meter readings may be falsely so and your issue may still be a weak front end, IF or the other two FM boards.
 
thanks!... I'll try this test as soon as I can, should be very interesting and hopefully revealing

RE: "I do find it interesting that the meter reads so high when tuned all the way to the left. Is there an adjustment for meter level and if so, was it adjusted? If so, the high meter readings may be falsely so and your issue may still be a weak front end, IF or the other two FM boards...."

yup, I know what you mean... it seems that the signal strength meter never really goes low, so perhaps that tech just "goosed it" so it looks like my reception is strong?... to be fair, it did come back pulling in stations much better than when I brought it in (but not in stereo!... and seems to have a fair bit of "weird noises" across the dial...)... I'm sure there's a meter adjustment, will look later
 
OK, I used my 2230 receiver to inject a "known good" FM signal into the FM-MPX board on my sick 2275

I used a patch cable between the two receivers made from shielded video cable... removed the RCA jacks, and soldered the wires in place, both the inner lead and outer shielding (temporarily)

powered up both units, started tuning on the 2230, and suddenly, FM was being received in stereo on the 2275!!!... every strong station was playing in stereo, plus the stereo lamp correctly lit up... EUREKA, so I was now able to rule out my FM-MPX P300 board as the culprit

or so I thought... this went on for a few minutes and all seemed good, then I went to get my camera... when I returned, suddenly NO MORE STEREO, back to mono... not even a tiny blip of stereo, all mono

I checked my connections, couldn't find any shorts, and the solder joints were holding... tried for 10 minutes more, still no more stereo... WTF!?... arrrgghhh... think I might lose my mind

I connected from pin J560 (on the 2230) over to pin J301 (on the 2275)... J301 is the main input to the FM-MPX board

hopefully I didn't damage my 2230 somehow, I have not removed the patch cable yet, still want to figure out what went wrong...


DSC04591.JPG DSC04593.JPG DSC04588.JPG DSC04585.JPG
 
Oh no, that sucks! Intermittent is a four letter word...

Make sure the cable didn't crack off at either unit. Check the bottom of the board where the posts are that the cable attaches to on the 2275, maybe it's cracked. You can probably wiggle it from the top and get a good idea if it's solid or not.
 
rBuckner said:
Oh no, that sucks! Intermittent is a four letter word...

Make sure the cable didn't crack off at either unit. Check the bottom of the board where the posts are that the cable attaches to on the 2275, maybe it's cracked. You can probably wiggle it from the top and get a good idea if it's solid or not.
Click to expand...
I will look tomorrow... actually, on the 2275, I de-soldered the pin and pulled it out, so I could keep the wire-wrapped connection intact

my jumper cable is about 6ft long... is that OK?... (should be, since it did work... at first anyway)
 
One thing to check is if you have a voltage difference between the chassis grounds of the 2230 and 2275 with your voltmeter on AC & DC. Both have non-polarized AC plugs (I don't know about in Canada) so if plugs are reversed from each other in the power strip either the hot or neutral can be tied to chassis ground through the 2.2M resistor. When you connected the grounds you made them both the same and the shield might be carrying current?
 
Dankik: I will check that (about the grounding and plug orientation)...

but I just thought of something: perhaps I need to adjust my R311 pot??? (on the FM-MPX board of the 2275... that fine tunes the 19kHz signal)

currently, R311 is sitting where I last had it set, which might not be correct and it might be sitting on the very fringe, hence changing during my test (remember that I found that rotating it made basically no difference, so my current position is nothing too specific, and thus questionable)... I'll try and report back
 
Last edited:
UPDATE:
- tried adjusting the R311 pot (on the 2275)... turned back & forth through full rotation, but made no difference, still no stereo FM... as before, turning this has surprisingly little/zero effect
- tried reversing one of the power plugs on the power bar, made no difference
- plugged the 2230 into a separate wall outlet, made no difference
- exercised all the buttons/switches, especially Mono and Muting (these were all recently cleaned), made no difference

on the 2230, when I briefly reconnected the disconnected wire to pin J560, stereo light came on, so it looks like it still has a good signal, and I haven't damaged the 2230!

still have to check solder on the posts of the 2275...

something I find strange: why was I able to get proper stereo for several minutes, uninterrupted?... that suggests something CHANGED during that time -- as opposed to being completely wrong or broken... perhaps a part warmed up, a very iffy connection got dislodged, a weird electrical charge built up, or ???... I was fairly careful not to bump things around too much, seeing as I had the jumper connected
 
Last edited:
OK, NOW THIS IS SUPER WEIRD...

I was probing around the 2275 looking for abnormalities, and I suddenly got stereo! (sound itself + stereo lamp)

then I accidentally discovered that it was the FLASHLIGHT I was using that triggered this "fix"

whenever I brought the flashlight near the stereo lamp (above it), and even when I moved it behind a bit (over the FM Front End), it triggered stereo!... even positioning towards the back of the receiver (over the right amp heatsink) would trigger... but not when over the FM-MPX board

the effect is most easily triggered by placing the flashlight directly over the stereo bulb, and over the FM Front End module... removing the metal cover from the FM Front End helps noticeably... as time went on, these two key areas were the only ones that triggered anymore

I also discovered that turning the flashlight OFF immediately stopped stereo, turning it ON immediately brought back stereo... I'm using a Energizer-brand 300 lumen 2AA LED flashlight, that gives of a faint buzzing sound when on low... model #TUF2AAPE (see photo)

I tried with a different brand LED flashlight, and that one did NOT work at all to bring stereo... it has to be the Energizer

*** I'm now suspecting that my previous triggering of stereo (post #49 above) was actually due to the flashlight effect, perhaps in combination with the 2230's good signal, or perhaps not (???)... I was using the flashlight at the time, and could easily have had it sitting atop the receiver ***

I also noticed that this effect varies with battery strength... the stronger the batteries, the more easily stereo is triggered

also, it seems to need some time to work... trying immediately upon powering up the receiver(s) does not work, must wait 10-20 seconds

using other objects (like metal pliers, etc.) does NOT trigger stereo

is this receiver haunted or something?... do I have to use a flashlight to listen to FM? jeesh....

MFG_TUF2AAPE.jpg
 
Last edited:
LED flashlights work by pulsing the DC to the LED at some high frequency. The battery strength could affect the pulse width/frequency. So, you are emitting some RF energy into the FM front end circuits that causes an oscillation that now receives the FM MPX signal. :dunno: What can we take away from this... perhaps an oscillator is not oscillating unless an external signal helps it to start oscillating? The other thought is that there is a grounding (shielding) issue that is present.
 
dankik said:
LED flashlights work by pulsing the DC to the LED at some high frequency. The battery strength could affect the pulse width/frequency. So, you are emitting some RF energy into the FM front end circuits that causes an oscillation that now receives the FM MPX signal. :dunno: What can we take away from this... perhaps an oscillator is not oscillating unless an external signal helps it to start oscillating? The other thought is that there is a grounding (shielding) issue that is present.
Click to expand...
your guess is likely better than mine!

however, keep in mind that I'm essentially using the "complete" front end from another receiver (the 2230), and injecting that into the FM-MPX board on my 2275... so I don't understand how any of the pre-MPX board circuits in my 2275 could come into play, since I'm injecting at a point AFTER these (like the P100 FM Front End, or P200 IF boards)... isn't it like they don't even exist anymore?

weirdly, the flashlight seems to affect all/most of the FM boards -- except for P300 FM-MPX!
 
Last edited:
WHOOPS?

as described earlier, I replaced (all of) the original 2SC828S transistors on my P300 board... (yup, shotgun replacement, since I'd seen others do that with success)

it was suggested to me that the transistors I used might not be suitable, since they don't have a high enough frequency rating, and that the original 2SC828S were rated for 220MHz

I used 2SC1815, which is what I'd seen used as a substitute on another "no-fm-stereo Marantz" thread, and they ended up fixing their problem... actually, they used KSC1815Y

Q: did I make a mistake using 2SC1815?
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom