I had previously written about this set. There was a "buzzing" sound when turn on was attempted. The green front panel light comes on but the set doesn't power up. I got into it and found that there is a power supply board on the right side. This is where the buzzing seemed to be coming from. There is a large heat sink lying flat which is on top of what looks like a huge (perhaps 3.0 X 5.0 ") IC. The heat sink runs warm. There are two voltages marked on a connector on this board. There are
5.0 volt and 15.0 volt points evident. The 5.0 volts was OK but the 15.0 volt line was at about 9.0 volts. There was also a capacitor on this board, C16. This is a 47uf 250 volt electrolytic which was bulged at the top and had unreadable ESR. I replaced the cap and the symptoms were the same. Within a minute or so the new cap was running quite warm. I powered down and checked all the diodes near this cap and they all seemed to be OK. The board was reinstalled at this point so I don't know what the voltage across the new cap was. Since something was going on around the area of that cap my intention was to briefly power up again and recheck these voltages. The set was powered up for about 20 seconds and I had just finished checking the low voltages when I heard a fairly loud "crack" come from the area of this board. There was no smell or evidence of any component failure, unless its that large IC under the heat sink which I can't really see very well. The buzzing is now gone and while the 5.0 volt line is still OK, the 15.0 volt line is now reading 12.0 volts. There are also two small fans mounted on two other boards on this set that do not run. Admittedly I may be in a little over my head here but I really don't want to walk away from this kind of work, especially when these things are so expensive and consequently so likely to have a repair estimate OK'D. Can anyone please offer some further assistance with this repair. Sorry that this is so long but I don't feel its possible to provide too much information when dealing with something like this. Thanks very much. Lenny Stein, Barlen Electronics.- posted
17 years ago