I have a question regarding a Marantz 2130 tuner I bought for my vintage audio system.
I just finished replacing all the electrolytic capacitors in the tuner and it seems to work okay with a couple of exceptions. First, the Quartz Lock worked but the indicator did not. I found that the pot RT48 was mis-adjusted causing the touch sensor to not dis-able the lock function. Problem is, someone hacked in some wires to work around the mis-adjustment. I undid the hack and now it works fine. I am worried the same hacker may have done more damage causing the two other issues I'm seeing. The problem is, when the multiplex filter switch is released, the right channel drops out completely. Also, when the "mono" button is selected the stereo indicator goes out. However, If I view the L & R output signals on my scope overlayed they appear to still be in stereo. Could these issues be due to improper alignment (MPX chip issue) or should I be looking for another wiring hack. It is very difficult to follow the signaling via the Marantz documentation. The multiplex switch appears to simply add in a .015uf capacitor into the circuit and does not seem like it should kill the right channel. If I examine the switch it appears there are lines on it's wire wrap pins indicating there were wires on them at one time but no indication in the schematics. It would be great to get some detailed photos of the wiring of a working tuner.
Any help would be greatly appreciated.
Gary
I just finished replacing all the electrolytic capacitors in the tuner and it seems to work okay with a couple of exceptions. First, the Quartz Lock worked but the indicator did not. I found that the pot RT48 was mis-adjusted causing the touch sensor to not dis-able the lock function. Problem is, someone hacked in some wires to work around the mis-adjustment. I undid the hack and now it works fine. I am worried the same hacker may have done more damage causing the two other issues I'm seeing. The problem is, when the multiplex filter switch is released, the right channel drops out completely. Also, when the "mono" button is selected the stereo indicator goes out. However, If I view the L & R output signals on my scope overlayed they appear to still be in stereo. Could these issues be due to improper alignment (MPX chip issue) or should I be looking for another wiring hack. It is very difficult to follow the signaling via the Marantz documentation. The multiplex switch appears to simply add in a .015uf capacitor into the circuit and does not seem like it should kill the right channel. If I examine the switch it appears there are lines on it's wire wrap pins indicating there were wires on them at one time but no indication in the schematics. It would be great to get some detailed photos of the wiring of a working tuner.
Any help would be greatly appreciated.
Gary
If the mono button is selected the stereo indicator should go out, surely? And if both signals are there on the scope, the fault must be downstream of wherever you are probing for that, and can have nothing to do with the MPX chip at all.
Hi guys,
When I depress the mono button the stereo indicator goes out. However, when I view the left and right channel line outputs with my external Tektronix scope the music waveforms are not the same. With the oscilloscope, if you place channel one over channel two they should be exactly the same if they were playing mono.
The multiplex noise filter button is not in the signal path per the schematic and is what is so confusing. Pressing that button should not defeat the right channel. For this reason, I think there is a wiring error. If someone has a 2130 I'll bet there is a wire or two wire wrapped onto that switch.
The switch is not dirty and I jumpered it to be sure.
Gary
When I depress the mono button the stereo indicator goes out. However, when I view the left and right channel line outputs with my external Tektronix scope the music waveforms are not the same. With the oscilloscope, if you place channel one over channel two they should be exactly the same if they were playing mono.
The multiplex noise filter button is not in the signal path per the schematic and is what is so confusing. Pressing that button should not defeat the right channel. For this reason, I think there is a wiring error. If someone has a 2130 I'll bet there is a wire or two wire wrapped onto that switch.
The switch is not dirty and I jumpered it to be sure.
Gary
Think the noise switch just connects a capacitor between the channels to reduce the HF separation.
It obviously shouldn't kill one channel, but it must be connected wrong to do that.
It obviously shouldn't kill one channel, but it must be connected wrong to do that.
Hi Rayma.
Exactly! This is why I am hoping for some photos from another tuner of that switch as it looks as though there was a wire wrapped around one of its pins.
Gary
Exactly! This is why I am hoping for some photos from another tuner of that switch as it looks as though there was a wire wrapped around one of its pins.
Gary