Originally Posted by ti-triodes
I just cracked open one of my 3575's to upgrade the HDD and found the following info.
This is a refurb unit manufactured 4/07 and refurbed 11/07.
Note there are some different numbers on the tuner.
My 5/2/09 post (#4658) described operational or performance problems with my April 2007 Sylvania ZV450 combo recorder (recently purchased used) that has the same UTUNNTUSP033/UI003AF tuner found in my July 2007 Magnavox 2080. While these tuners have the same part number they are from different lots.
Ti-triodes reports that the same UTUNNTUSP033/UI003AF tuner is used in an April 2007 3575. That tuner's LOT FUDe is the same lot as that found in my July 2007 2080.
Perhaps the same UTUNNTUSP033/UI003AF tuner is used in the 3576 and the 2160 as well.
My Philips 3575 and Magnavox 2080 and 2160 models operate and perform very well.
My Sylvania ZV450SL8 does not tune digital sub-channels below the channel 73 range and can only access digital sub-channels in the channel 73-118 range through direct channel entry. The remote’s channel up/down buttons select only between L1 and L2 when DTV is selected. Analog channels may be tuned with channel up/down or through direct channel entry when TV is selected. Wajo, dww and Dartman gave advice ranging from upgrading the coax cable, switching back to analog and then back to digital or holding the remote’s DTV/TV button. These remedial measures have not corrected the problems. Yesterday I moved the ZV450 to a different room where a six foot length of shielded RG6 coax was connected directly from the 2080 RF output (for an amplified pass through signal) to the ZV450. A re-scan of the channels resulted in no functional improvement.
The Magnavox 2080 continues to tune all the digital sub-channels with channel up/down or through direct entry.
Are the Sylvania ZV450 problems a sample defect or are these problems inherent to the ZV450 model? I don’t know.
While operational or performance differences might be attributed to sample variations/defects, another explanation may be found in hardware/software differences resident to these models’ “MAIN PCB.” Photos of the Main PCB of my 2080 and ZV450 are attached.
Update 1: As of 5/22/2009 the Sylvania ZV450 only intermittantly directly-tuned clear QAM channels in the channel 73 and higher range, even after running a new (enhanced, i.e., "analog and digital") channel scan. The splitters were recently upgraded from 5 MHz-1 GHz models (Regal GS2DGH and Ideal 85-134) to 5MHz-2.3GHz models (GE/Jasco AV22694 and 87625). The 2080, also set up cable-ready, continues to tune the clear QAM channels as normal. On 5/23/2009 the ZV450 was set up for OTA (ATSC) reception where it appears to function normally.
Update 2: In recent weeks the Philips 3576 has developed the same weak clear QAM performance deficiencies as the Sylvania ZV450SL8 (subsequently given to a daughter who reports that the Sylvania is satisfactory for her use). A few days ago the 3576 was reconfigured for OTA use where it performs satisfactorily.