Onida Ultima Chassis CRT TV Circuit Diagram - Channel Skipping fault
Onida 14PROFILE/14ELITE - 20PROFILE/21ELITE - 20XS/21IQ - 14XS - 21FLAT
Used ICs: M61264 – M37160 – 24C16 – 2616 – TDA7449 – AN5522
Onida Ultima Mono - Circuit Diagram
Onida Ultima - Stereo
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Channel skipping in 20XS DLX in VL band (
Ultima couple chassis )
Even with channel +/- Manual search and fine tuning also the channels are not getting locked. The reported problem was not seen in ES set having Philips tuner SR No : CO20XSST-4000004
The problem of channel skipping is observed only in VL band in cochin godown the signal strength is 68 dBuV to 75dBuV for entire VL band.
The skipped channels were getting tuned with repeated manual ch. Search +/-ve and the skipped channels were 100 % getting locked with fine tuning.
With repeated Auto tuning there was no consistency of channel skippages observed as during first auto tune less channels and with 2 , 3 more no of channels were observed to be skipped. There was no consistency of program Nos being skipped always.
The problem of channel skipping was not seen with Philips tuner after AUTO VIF VCO adjustment in service menu.
With AUTO VIF VCO adjustment with Savak tuner there was improvement seen with less no. of channel skippages reduced down to 2 / 3 channels from 6 to 7 channels. However there was no
consistency. On one to one replacement of Panasonic tuner in place of Savak tuner there was no channel skippages observed.
With fixing of VIF VCO Alignment to digit 26 and reducing the tuning speed through Service.
Even with channel +/- Manual search and fine tuning also the channels are not getting locked. The reported problem was not seen in ES set having Philips tuner SR No : CO20XSST-4000004
The problem of channel skipping is observed only in VL band in cochin godown the signal strength is 68 dBuV to 75dBuV for entire VL band.
The skipped channels were getting tuned with repeated manual ch. Search +/-ve and the skipped channels were 100 % getting locked with fine tuning.
With repeated Auto tuning there was no consistency of channel skippages observed as during first auto tune less channels and with 2 , 3 more no of channels were observed to be skipped. There was no consistency of program Nos being skipped always.
The problem of channel skipping was not seen with Philips tuner after AUTO VIF VCO adjustment in service menu.
With AUTO VIF VCO adjustment with Savak tuner there was improvement seen with less no. of channel skippages reduced down to 2 / 3 channels from 6 to 7 channels. However there was no
consistency. On one to one replacement of Panasonic tuner in place of Savak tuner there was no channel skippages observed.
With fixing of VIF VCO Alignment to digit 26 and reducing the tuning speed through Service.
011 > 1A
0DA > 71
0DB > BC
0DC > E2
0E0 > A9
0E1 > 10
0E2 > A0
0E3 > 07
0E4 > 4C
0E5 > C0
0E6 > E2
0DA > 71
0DB > BC
0DC > E2
0E0 > A9
0E1 > 10
0E2 > A0
0E3 > 07
0E4 > 4C
0E5 > C0
0E6 > E2
The above ROM correction through service menu is also found to be successful with GDC , Panasonic and Philips tuner tried.
The above solution was tried in 27 sets which include 7 sets with Panasonic tuner, 2 sets with Phillips tuner, 4 sets with GDC tuner and rest 14 sets with Savak tuner.
7 sets were soaked for more than 2 hours and confirmed the effectiveness of the solution, then the same sets were switched off for approx... 1 hour and was again confirmed the 100 % effectiveness of the solution. Also the same sets were repeatedly auto tuned for three times and found the consistency of all the channels locking in entire band
