Post B7T0WZY58AeLe9mWwa by Stellar@mk.absturztau.be
(DIR) More posts by Stellar@mk.absturztau.be
(DIR) Post #B7SSKZLeeZMT6n4e80 by Stellar@mk.absturztau.be
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the repair is NOT going great, i decided to recruit some help. :ankhafirerage:
(DIR) Post #B7SSYmOyuuUteEPF7w by jessew@mk.cpluspatch.com
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@Stellar@mk.absturztau.be why do you have anal beads everywhere
(DIR) Post #B7SSYmeZyuySQbhhRI by Stellar@mk.absturztau.be
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@jessew@mk.cpluspatch.com It's pride month, keep up.
(DIR) Post #B7SX09miUIxdntolwu by kate@mk.absturztau.be
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@Stellar ..that looks like a switching power supply? Those often follow weird schematics and make use of very rare components and rare silicone...
(DIR) Post #B7SX09yPmoJoOBI7BQ by Stellar@mk.absturztau.be
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@kate its one of 3 pcb from a sound amplifier, it keep blowing its fuse and i don't know what i'm doing, i've tested all capacitors and they're ok. i don't know what to do next. :blobcatsipsweat:
(DIR) Post #B7SZbjNbJFOIp37AeG by kate@mk.absturztau.be
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@Stellar .. in wich case you should check all other components. I assume you haven't got any schematics of this?Those switching power supplies often do have protective fuses in the input section close to where the power cord is attached. Some do have over current and over voltage protection. Some of these are "one way" components. They usually connect between the live wire and protective earth/ground. So they could be permanently shorting the input after having saved your electronics once against overcurrent or overvoltage. They often look like blue insulated discs with two wires. Some are also orange or black, but blue is most likely. When you post a photo with better resolution I probably can come up with more hints if you like?
(DIR) Post #B7SZbjZeaR23QQknR2 by Stellar@mk.absturztau.be
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@kate oh god, there is like 8 of them blue insulated disks, they all read open with DC. is it expected?
(DIR) Post #B7Sj2vguXiy0PbBtx2 by kate@mk.absturztau.be
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@Stellar ... they all should have a resistance of megaohms. But, this isn't always easily measured with a battery powered meter as the probing voltage might by 9 volts max. They still might break down when 120/230 Volts get attached.Also there usually is a bridge rectifier somewhere that creates DC from the input voltage first before that is switched down by various switching units. Since you checked all capacitors the rectifier might have a single diode or more shorted. Which can blow your fuses anytime too. When you like just shoot a photo more close up of all the PCBs and I have a look what you can check. When you feel it is not for the public feel free to post it in a private message to me.
(DIR) Post #B7Sj2vxvWSZtGN9UTQ by Stellar@mk.absturztau.be
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@kate i took closeup pictures
(DIR) Post #B7Sno1bWm7p8B7NwgK by kate@mk.absturztau.be
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@Stellar Great! .. so ... all your blue disc items are capacitors, so far so good. The PCB has descriptive names of components on it, which is great.The is one component close to the input terminals that looks like a black disc and is makred on the PCB as VDR ... Check any and all components that bear that name VDR. VDR is short for Voltage Dependent Resistor. Those react to overvoltage and should afterwards self-rest to a high resistance again. Your meter should show many Megaohms.Also a bit further there is the bridge rectifier in a black plastic casing that is characterized by a cut off edge. In case you can identify the brand and name of the rectifier you could find the layout of the connectors. If not you can try this: usually the two middle wires of the four in a row are for the AC and the two at the end of the connector row are the DC connectors. Just check all 4 connectors for a short with your meter.All the bigger capacitors look like in good shape. A faulty capacitor is easily found by checking the metallic bare top of the capacitor where there are some fine lines in the metal. These lines are the intended cracks in case the capacitor has overloaded and would blast off. There are no dark spots or visible coal like burnings anywhere as far as I can see. So that is a good sign.Now for the sinister things. Just in case all the above checks do find nothing the culprit might be an overloaded transistor in the switching sections. Also there are several diodes visible. All those are very hard if not impossible to check in-circuit. What you can do however is check their terminals from the soldering side for any shorts. However, since the switching sections connect the transistor switches to chokes and transformers with very low resistance, so a low meter value doesn't tell you if it is a short or not in all cases.Make sure your values are really zero to conclude it is a short inside the diode or transistor.Proceed to all your PCBs in that way to find any clues or faulty components.Get back to me with any or all findings and photos of the other PCBs if you want.Also feel free to send me messages to my e-mal if you want.Also yet another hint: if possible check all transistor switches for their ID, name and brand. That might help a lot later on to find replacements and the layout of thier respective connecting wires. Good luck!!
(DIR) Post #B7Sno1rpnUrqzh0y6C by Stellar@mk.absturztau.be
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@kate yeah i've been prodding around the soldering side for a while, that black disk you talked about that has the double-diode symbol is reading a very high resitance reading both way of something like multiple megaOms. there is so many lines that goes everywhere on the live side and idk if i'm supposed to read open, high or low resistance on them
(DIR) Post #B7SokxP82B34Engdeq by Stellar@mk.absturztau.be
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@kate i did some doodling to show here stuff is on the soldering side
(DIR) Post #B7SqDZIIqzhpoVhVzc by Stellar@mk.absturztau.be
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@kate i've checked the rectifiers, they are infinite oms resistance, so i guess they are not shorted, and the low-voltage side of the rectifier reads low oms (500 Oms) but i think its because of the capacitors bridging them. what's strange is the blue capacitors aren't getting charged by my multitool unlike the normal cylinder capacitors, because the resistance reading is not increasing when reading them. also i got more photos
(DIR) Post #B7SsrS4pJ5PkvAXjBg by Stellar@mk.absturztau.be
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@kate oh god i think i figured it out: i've been putting F5AH 250V fuses in, which instantly exploded in a bright flash when plugging in the amp, where can i get those T fuses?
(DIR) Post #B7Swz5tW429yFz9V5c by kate@mk.absturztau.be
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@Stellar ..those blue capacitors have a low capacitance, so their loaded even by the small voltage of your multitool quite quickly so you do not see them loading.
(DIR) Post #B7Sx1jUhntl9eWo0Bc by Drayventhal@mk.absturztau.be
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@Stellar @kate AFAIK you can buy those fuses in hardware stores.
(DIR) Post #B7SxTWlciU4KHwyLGi by kate@mk.absturztau.be
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@Stellar the fast-blow glas fuses of that type should generally be available in stores that sell electronics and fuses. Amazon has them too.When the fuse blows it means that the current rushing through is far too high, hence there is a fault or short behind it.
(DIR) Post #B7SxTWznrlPYzvbfN2 by Stellar@mk.absturztau.be
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@kate yeah but F5AH is fast and T5AH is slow? i only have F type, and i tried opening all the other old electronics but none of them use a 5 amps slow fuse
(DIR) Post #B7SyEFHJYcAfes4XjM by kate@mk.absturztau.be
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@Stellar Yes the T means slow and F means Fast. 5A means that the fuse blows at 5 amps or more. So that PCB is protected by it and the fuse avoids the PCB to burn and hence avoids fire. T5AH are quite common, also higher currents are available. Those glasses fuses are also available up to 10 A. The higher value fuses are filled with sand which you easily can see in case you have one of these. Do not attempt to replace this fuse with one of higher current value! This only increases the risk for more damage.
(DIR) Post #B7SyI6HExv7atqsMIS by Stellar@mk.absturztau.be
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@kate well i'll get a box of them on aliexpress.... oooh they sell killer queen ties... oh ... i could use a new phone case...
(DIR) Post #B7Sz6ycZBqERvL6vQG by kate@mk.absturztau.be
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@Stellar be careful when you get a set of these. My experience with sets is that they sometimes mark the fuses with cryptic text and not the standard terms for the rating.The rating should be carved on the metal ends. sometimes it is also printed on the glas. And in cheap-o boxes the have none. You must be careful to read the little inscriptions on tiny paper stickers in the box. Beware!
(DIR) Post #B7SzjUTxBCFZk9RlXE by Stellar@mk.absturztau.be
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@kate damn, times are hard, its hard to shop nowadays :blobcatpensive: necessities are so expensive /jk
(DIR) Post #B7T0TXWqBVx0VrksuO by kate@mk.absturztau.be
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@Stellar ..that is insane! Those boxes must have hundreds of fuses in them? IN any case I guess that is total overkill?Cannot you just purchase twenty of those you need?
(DIR) Post #B7T0WZY58AeLe9mWwa by Stellar@mk.absturztau.be
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@kate no i'm kidding its 2 bucks with 1€ shipping, i was making a joke because i have filled my cart with 12 other useless stuff i always see when looking for stuff on there