did you meter the mosfet out of the board?
-
-
"Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
-David VanHornComment
-
I am not getting something... first, you had a short on the 2 prongs. You took the Mosfet off, made no diff. Then you took that SMD cap right above the 2 prongs off, now the short is gone on the prongs but the SMD cap isn't shorted? Doesn't make any sense to me.Comment
-
SMD ceramics are rather delicate, they can be damaged if you solder them wrong and thermally or physically shock them, it's possible to disturb the short internally or crack the capacitor by desoldering it, especially if done with a soldering iron rather than hot air. Then the short would appear to vanish.
I've also had disappearing short circuits on tactile buttons, once the part is desoldered. My guess would be tin whiskers internally on the switch contacts that melted, or similar."Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
-David VanHornComment
-
tactile switches are usually silver plated, maybe the black tarnish that builds on them is conductive.
Comment
-
Nah… that black stuff makes contacts worse, not better. At work I have sometimes trouble with switches because they use cleaner on them.Comment
-
Good morning everyone,
I'm trying to repair an onkyo ht-r390 that has no sound output, despite the volume being at maximum, the rest seems to work; the video output signal (coming from an hdmi input) is present, but the audio is absent. Similar situation if I send an audio signal from any input I have no output.
The firmware reported is the following:
M:1.00/11107BLP
D:?.??/????????
O:1.00/11107AL
The DSP firmware given the question marks seems corrupt.
On the BCHDM-0678 - 25140678 - QPWBCHDM0678A0 board the chip that usually seems...05-11-2025, 02:59 AM -
I have bought this Zener Diode for this project what size and wattage resistor value do I need to use to get near 50 watt output
I bought this from an eBay seller but unfortunately they only had one
I bought three from Vetco Electronics these are Sylvania ECG5185A 9.1@10w A to Stud what size and watt resistor do I need to use to get near 10 watt output
I bought three of from them to also make battery packs with this output power limit in mind
I want to use this battery pack and turn it into a 9.1 output battery pack output to eliminate using 9 volt battery... -
Looks like I may need a little help from the PSU experts (or anyone really!
) I have a Corsair CX750M (Model 75-002019) that I picked up for free about 4 years ago. This is the PSU:
So here’s what’s strange about this one: it appears to work normally (normal output voltages) and any PC is stable with it. However, after a while (typically 10-20 minutes, but time can vary depending on the load), there is a sweetish smell of burned magnet wire insulation emanating from the PSU. Upon opening the PSU after this happened (many times), I was able to confirm... -
Hi:
I bought this amplifier from the 70s to try to repair it. So far it has no output sound, just noise. You can volume it up and down.
I've checked fuses and all are ok.
I've continued with capacitors:- The main black one should have 4700uF, but it has lost half of its capacity during these years.
- The ones that I've numbered have still a really low ESR and the full capacity after ¿40 years?
The 4 transitors are perfect. Desoldered and tested individually.
There are also components which I don't know exactly what they are.... -
Surprisingly enough, this receiver doesn't have the DSP chip issue. The HDMI board does not get hot, and sound over HDMI works fine.
Regardless of the input, the right channel has noise that is clearly noticeable even on average volume level. The only cases when there's no noise is when VCR input is selected (some tracks on the board are damaged, maybe that's why), or if HDMI input is selected but nothing plugged into it. In all other cases, even when no input is connected I still have the noise.
There's some logic behind it. As soon as I select an input I get only left...04-23-2025, 10:09 PM
Comment