The 22 Month Eletrolytics

The well-known problem was with the DVP 642. I found the info on the web site

An article there gave the actual part number which is printed on the circuit board for that particular capacitor.

The URL, above, also has info on other Philips DVD players. Have a look.

--- Joe

Yes, agreed. Most LCD TV switchers have sophisticated shutdown circuitry for the main control IC, and sometimes for the pfc supply as well. These circuits measure under and over voltage, as well as over-current conditions, and can represent a fault-finding nightmare, as you try to over-ride them with the supply in isolation from the TV, to see which supply or protection circuit, is causing the shutdown ...

But as you say, most cheapo switchers as found in DVD players and home cinemas and the like, have absolutely nothing south of the rectifier.

Arfa

I don't know specifically with your model, but the most common problems caused by bad electrolytics in items like this are no or intermittent operation, a failure to come out of standby, a failure of the standby supply to come up if the unit has been fully off-power, pattern on the screen of the display, or random error messages on the screen like "no signal being received" or some such.

If there is no physical evidence of a bad cap, such as bulging, leaking, or a popped bung, then the best (and only, in my opinion) way of locating bad or 'on their way' caps, is with an ESR meter. One of these will locate 99% of bad caps without even having to remove them from the board, and is worth its weight in gold to a commercial repairer. In saying that, measuring ESR is a bit of a black art in terms of interpreting the readings the meter gives you, but the digital types like Bob Parker's (now remodeled to the "Blue ESR Meter" - see Anatek Corporation's website) make this interpretation a whole bunch easier. Secondary-side caps are the most common for giving a physically visible clue, and the worst offenders are those mounted close to a heatsink. Primary-side troublemakers are usually physically small low-value types - up to about 47uF - and are almost always mounted close to a heatsink. Dead supply with no blown fuses, is the typical symptom from these.

The best thing that you can do to prolongue the life of any power supplies in DVD players or HC units, is to make sure that they are not locked up in a cabinet with poor airflow, and that they are on the bottom of any equipment stack, so that they are not drawing warm air from some unit underneath.

Arfa

"Arfa Daily" wrote in news:sKgnn.362533$ snipped-for-privacy@newsfe27.ams:

The SMPS in TEK 1710/20/30 series TV products would have the cap on the +5V rail rise in ESR,the supply would drive ALL the other supply rails high, the +40V would climb to >60v,the HV oscillator xstr would overdissipate,char the PCB to the point it became conductive,and the supply would go into "burst" mode. I had to grind out the charred area,fill with epoxy,and set new eyelets and do track repairs.I also put in a better rated

Other techs just replaced the whole PCB. I was always replacing bad electrolytics on the 1700 monitors. They typically were installed in racks that kept their temp above "normal".

Sorry It's you who crashed, several years ago in fact.

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I've seen this with quite dramatic consequences. 2 years ago a friend brought me a budget DTT-DVD player which was dead. Opened up,and several caps had literally exploded, but only one was in the psu. the others were downstream, on the main/processor pcb. Clearly there had been some catastrophic voltage rise.

The other week I picked up a DTT set top box. Same thing - lots of exploded caps, with only the legs still on the pcb. The few remaining electolytics on the main pcb were bulging. Needless to say, both these units were promptly scrapped as BER. The lesson is: when something is acting erratically, don't wait before changing the caps!

-B

Hi!

Every cap in the switch's SMPS was fine, and the outputs were right on. A large (filter?) cap on the main board blew its top. It looked like it had been working up to this for a while. It had been working great up until the moment it fell off the wagon.

A replacement cap didn't help much, and I sure couldn't complain about six years of service from a used switch that I paid all of $10 for. I saved the SMPS for later use and recycled the rest. A new D-Link switch replaced it. What struck me was how the components have shrunk. The SMC switch had several large ICs, two of them responsible for switching and one that appeared to be a sort of processor (for what I have no idea, it was not a managed switch). There were some artifacts near the processor for RAM and ROM, probably used to add management functionality?

The D-Link switch is based on a Realtek platform. It runs cooler, performs just as well and is a simpler design.

William

This looks like a good thread to jump into:

I have a friend that has a Hafler TA-1600. The bass is non- existent and every thing else is a bit flat/muted. Each channel has a separate board powered by a common, multi-tap, dual voltage transformer that outputs ~32 and ~64 VAC with

The transformer has two input leads and 12 output leads. One group of three per board per voltage.

Each board has two power inputs, comprising the above voltages, that contain three leads each that are Red - Black - Red. Red to red gives the 32/64 volt for each input, while any red to black combination gives half of the red to red voltage in that winding group.

There is not any visible damage to any component. Each board sounds identical to the other when isolated. This amp is currently disassembled so that I may work on each board individually, yet I'm not sure whether attempting to save the system is actually worth the bother.

With reading all of the electrolytic problems that seem to be permeating the electronic field, I am seeking information to a possible fix, and hope that maybe someone here might actually have some experience with the Hafler TA's and could point to some resources/give some hints or how to's with this unit.

Thanks,

Steve

PS: the voltages listed above are measured voltages. The transformer does not have any specs listed on it.

If the sound is identically bad on both channels, that suggests something common to both channels, such as the power supply. The possibility that a coupling cap has suddenly lost value is unlikely, as the same cap would have to fail on both channels.

I would also look at the /system/ in which the amplifier is installed. The lack of bass might be due to an interface problem elsewhere.