siriushardware wrote:As you've noticed L305 /L306 are only supposed to have two actual connections. However, components with only two pins are prone to wobble back and forth so sometimes coils / inductors / transformers have extra legs which are not connected to any part of the coil winding. Their job is just to provide more solder anchor points to the PCB.
czietz wrote:The schematic gives it away: These are not simple inductors.
Fujiyama wrote:Are they all the same? The schematics say nothing about their values.
siriushardware wrote:In the light of that clarification from Czietz, it is actually possible that the capacitor in the T-filter assembly has gone short circuit.
You can verify this by taking out the suspect coil/filter and measuring the resistance from each terminal of the component to the others. Your meter should see a dead short, more or less, between two of the pins.
From those two pins to the third pin (the one which normally goes to zero volts on the PCB) there should appear to be infinite resistance, although you may see a brief flash of lower resistance when you first connect the meter. If all three pins appear to be constantly shorted to each other the device is faulty.
If that proves to be the case, what I said before still applies - these components are just interference filters and you can bypass a suspected faulty one by linking from one side to the other and leaving the third (0V connected) PCB hole unconnected. If that solves the problem, by all means try to source a replacement filter.
dhedberg wrote:How about Quest Components?
https://www.questcomp.com/QuestDetails. ... partsearch
Fujiyama wrote:dhedberg wrote:How about Quest Components?
I just registered with them (in order to check the shipping costs) and found out that there's a minimum US$ 25 order (100 of those T-filters) and the cheapest shipping method would be US$ 50, so in total US$ 75 for 100 of them. And that's not even including import duty and taxes. I estimate the total would cost me around US$ 94 which is a bit much considering I just need one (plus possibly a couple of extras in case the other filters need replacement some time).
Fujiyama wrote:How do you find equivalents for components like this? Is it a matter of knowing your stuff, understanding datasheets and comparing, or are there dedicated websites/databases for this very thing?
Fujiyama wrote:Also, are these filters parts that commonly wear down and need replacing (like electrolytic capacitors), or have I just become very unlucky?
Fujiyama wrote:The STe service manual lists several different filters (see image attached) and I assume its similar to what is found in the Mega STe. But it's hard to tell which filters go where. Can you decipher it better perhaps?
Fujiyama wrote:I've started getting an "out of range. 15.8KHz/60Hz" message on the LCD display itself. It often happens if I do a reset (CTRL-ALT-DEL or pressing the reset button) even though the computer has booted fine. Could the monitor be at fault?
Fujiyama wrote:I think you're right about "ALT" meaning alternative filters as this doesn't seem to be a critical valued part. According to the list there are 5 options, but the ZJSR5101-102 isn't mentioned. How did you figure out that one?
Fujiyama wrote:I should probably take a closer look inside the Mega STe to see if I can find "102" markings on all of them. There are quite a lot of those filters, probably 50 or more, attached to each connector (serial, parallel, MIDI, ACSI etc.). Are they to prevent voltage spikes from coming in and destroying the other components nearby?
Are they to prevent voltage spikes from coming in and destroying the other components nearby?
siriushardware wrote:Well done on finding that faulty filter. I have to admit that's a long way from being the first thing I would have thought about, but your persistence has paid off. At least you don't have to replace the Optocoupler after all.
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