Hi, UD-503 Service Manual and Schematic can be found here (no charge for download, just wait a while before download appears) https://elektrotanya.com/teac_ud-503_ver.c_sm.pdf/download.html https://elektrotanya.com/teac_ud-503_sch.pdf/download.html BR Flemming Bach Andreasen Denmark

Some guy in the US own the right to the name Mometum, so in the US (and also Turkey) it will be named to HD-1.   Cheers Flemming Bach Andreasen https://www.linkedin.com/in/flemming-bach-andreasen-756a703

It the same as Momentum 2.0 Wireless, it just a name change.   They can not use the name Momentum.. That the reason!

It is the same as Momentum 2.0 Wireless, it just a name change.   They can not use the name Momentum.. That is the reason!

Hi,   Try to insert the jack plug into the M2 Wireless, while they are turned on, after 10-15 seconds remove the Jackplug.     Jackplug inside the M2 Wireless has a BT radio On/Off function (Flightmode) and this switch can if it is dirty hang.  You might need to perform this multiple times. ...

If you liked the Momentum Wireless, you should definitely try the new Sennheiser PXC-550 Wireless.   http://en-us.sennheiser.com/pxc-550-wireless   Same Danish team that was behind the M2 has worked on the PXC-550 product!   This time the BT link works in the release version! It even has a...

Is your powercord grounded ?     It could be an ESD pulse that reset/freezes the electronics.    BR Flemming

Hi AudioQuality777   From what I remember, when I modded my UD-503, the Analog RCA inputs are converted on the small input PCBA to balanced (TI NE5532 opamp for each RCA input, also dual mono PCB split), and are feed to the second inputs of the NJW1195.    Just like the example from the data...

Hi,   M2 Wireless has three speech microphones, all three are used to pickup the voice. But there is some DSP signal processing involved to obtain some directional beam forming. This is the reason that you are tricked to think only one is picking up the voice.      It sounds like the...

I dont think it is worth the money, to buy an external Clock for UD-503.     Look at HiFi-News Jitter measurement on USB:  28pSec jitter   To my understanding the 10MHz ref input options is onlyworking for USB input, not the Coax/Optical SPDIF !?  

Hi AudioQuality777   It looks like your NT-503 has an additional Switch-Mode power supply. This is properbly to supply current to the extra Digital interface PCB´s  that the NT-503 has.    Can you take some more pictures of your NT-503 of the Inside ?    Cheers Flemming

You need an Allen Key or Umbraco key (can´t remember which size) to remove the side screws. This goes as well for the aluminium lid, it just an smaller Allen key.      Remember UNPLUG the 120/230V power chord if you decide to open your UD-503, due to the risk of electric shock, if you dont...

Hi,   Chord 2Qute DAC seems a bit overpriced... no Stereo XLR, No Headphone amp out, no RCA Line in, does not support DSD256, no way to select between NOS and upsamling, No possiblity to select different digital filters.   The Teac UD503 gives a lot of bang for the bucks!!  And it sounds...

Today I did a little reverse engineering on the UD-503 Ouput amplifier circuit.  Total there are 4 of these output amplifiers circuits (Stereo Balanced) but only one is shown here.    I think it is a pretty good way to implement a push-pull output stage with an Opamp as driver.  They even...

:thumbsup: Im glad that it solved your problem! :grinning: If this problem shows up again, please let me know. Cheers Flemming