• 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

mpx

  1. Richard P

    Sansui 5500 No Stereo, Clear Mono

    I'm working on a Sansui 5500 receiver and am having an issue with the FM Multiplex board. I get good FM reception but no stereo. I have a good 19 kHz, 3 Vrms signal after TR402 and a 38 kHz, 1Vrms signal at the base of TR403 but no 38 kHz on the collector of TR403. DC voltages around the...
    • Richard P
    • Thread
    • 5500 mpx multiplex sansui stereo stereo separation tuner
    • Replies: 45
    • Forum: Tuners
  2. Carbsandcaps

    Is there a way to tell if a receiver or tuner has multiplex?

    Looking into buying a Grommes 502c receiver. I’m trying to figure out if it has multiplex built in or just doesn’t have the option because there’s no multiplex out connection. I don’t think there are enough tubes for multiplex but I can’t tell and I can’t find a service manual anywhere for it.
  3. Carbsandcaps

    MPX 19khz amplitude question

    I was wondering if anyone knows at what amplitude the 19khz tone has to be at to “activate” the mpx. I’m trying to get a relay to work in a fisher mpx unit but I can’t get a good mpx signal where I’m at so I’m using a signal generator. I can get voltage at the relay coil but it’s varies pretty...
  4. Carbsandcaps

    Kenwood tuner confusion

    I just picked a kenwood kw-100g tube tuner and it has this “stereo monitor” option. I don’t really understand the instruction. When it’s in stereo monitor there’s some static and the station can be heard faintly. Is this a very overcomplicated way to test the multiplex signal instead of a simple...
  5. Carbsandcaps

    Tuner alignment by ear (ya I know)

    So ive got a Harmon kardon st-350 tube tuner that im trying to get to work with my fisher MPX-100 multiplex adapter. I can’t get stereo no matter what I do. Now the history on the tuner… When I got the tuner it had nothing. No am or fm. Replaced some bad tubes, still nothing. Decided to mess...
    • Carbsandcaps
    • Thread
    • fm radio alignment mpx mpx 100
    • Replies: 11
    • Forum: Tuners
  6. D

    LA3401 Multiplex Decoder

    I have a vintage Voice of Music receiver that works fine, but will not provide FM stereo. I replaced the original MPX board with a modern design based on the Sanyo LA3401 chip. I got the board working and restored FM stereo, but I can't figure out how to wire in the mute feature. According to...
    • Dan_B
    • Thread
    • la-3401 la3401 mpx mulktiplex pll
    • Replies: 2
    • Forum: Solid State
  7. David Weaver

    Question to TU-888 Owners

    I recently acquired a cosmetically very nice TU-888 but it has the common issue of the FM indicator and stereo indicator lights not working. Upon cleaning and inspection I noticed a a transistor and cap mounted to the underside of the MPX board (F-1283). The service manual does not indicate...
  8. Geek

    MX-110 MPX Matrix Issues

    Hi Folks, Gotta MX-110 on the bench here (Ser. 188Z6) with a unique issue I have not encountered before. Problem: All (including FM Mono) works awesome. MPX position delivers a mono L-R (left minus right, the info contained on the 38KHz DSB subcarrier) to the speakers. There appears to have no...
    • Geek
    • Thread
    • matrixing mcintonsh mpx multiplex mx-110 tuner
    • Replies: 6
    • Forum: McIntosh Audio
  9. T

    HELP! Marantz 2230 - wiring under P300 board

    I am a big dummy and I forgot to take before photos of the wiring under the P300 MPX board in my 2230. There are two posts on the underside of the board that had a wire going to each of them. They are labeled J316 and J30(5?) PXL_20201005_214115530~2 by tinwhiskers posted Oct 5, 2020 at 4:56 PM...
  10. ukfan4sure!

    MPX Adapters -- Please Skool Me?

    I'm looking to get a MPX adapter for my P-22 as I'd like to hear FM in Stereo. It would add a warmth and depth to the music I would hope. Maybe the MPX-100? Or is it the MPX-200? For my chassis, which one(s) would I need to search for? Thanks in advance!
  11. V

    Reference 180r

    Hello. I am working on a Reference (by Quadraflex) 180r that is in fantastic cosmetic shape and works just fine except for no FM stereo/no stereo light (the light was blown, I have replaced with an 8V30mv lamp) I have cleaned the mono/stereo/MPX toggle as well as variable resistors on the FM...
    • vmedia
    • Thread
    • la23350 mpx quadraflex reference
    • Replies: 1
    • Forum: Solid State
  12. pgena

    MR77 Loss of MPX?

    My Mr77 sounds fine, but at around 10 minutes after power-up, the right channel gives way completely to white noise. Though the station is strong (6+), a quick turn of the Stereo Filter switch to 1 returns the sound on the right and the sound is clear for the duration. If I switch the filter...
  13. tusntuk2

    Sx-626 FM Stereo problem - Does this sound familiar? Need some help.

    Just finished recapping a lovely little SX-626, and the FM board doesn't want to go stereo. The Muting switch sometimes works, sometimes cancels all strong signals and goes silent. The Stereo light flickers while tuning, sometimes indicates stereo on weaker stations, but often does not glow on...
    • tusntuk2
    • Thread
    • awe-011 decoder fm stereo mpx multiplex muting circuit stereo light sx-626 tuning cap
    • Replies: 5
    • Forum: Pioneer Audio
  14. QSilver

    TX-9100 strobing/unstable stereo

    I finally found one of these after much searching. There's a little rust on the back grill but besides that, the case is in great condition. FM and AM are great but the Stereo is not working so well. Basically what happens is that when you tune into a stereo broadcast, the stereo lamp starts to...
  15. S

    Does anybody do tuner alignment in Vermont/Northern New York

    Im looking to see if anybody around northern New York does tuner alignment, I have a Fisher 400 that I would like to get the tuner back to full performance but lack the equipment.
    • streetwise
    • Thread
    • alignment fisher mpx tuner
    • Replies: 5
    • Forum: Tuners
  16. PooPoo

    Does anyone know if the 2275 MPX board is interchangeable with other models? Need to replace it

    I need to replace a 2275 MPX board but can't find any on eBay does other models have the same board I can use on 2275? Also my signal strength meter is completely dead sometime when left off for awhile it will work for a few seconds then go completely dead.?!
  17. T

    Marantz 4400 - tuner MPX board - help needed

    Hi all, I have a 4400 with no stereo. tuner works in mono only. I am trying to remove the MPX board. - any idea on how to do this without taking the 50% of the 4400 apart? what are the typical components which fails on this board? I intend to replace all the elcos Thanks Robin
  18. Briant8

    Dadgummit! 2275 MPX board recap, now no radio...

    Hi all! I've been following along with both thxdave and Steven Tate's threads as it seems that we are all currently recapping a 2275 (how do you guys insert those cool short blue links? Was going to link to those threads and the parts list, but it comes up as the big long URL address...)...
  19. NazcaRecords

    Marantz 2245 P300 board parts list

    Hello Has anyone perform an upgrade on a MPX P300 board with new parts from either Mouser or Parts Express. Thank you
Back
Top Bottom