Nice mods... I can see four 330uF SEPF's ($7.20), 2 Coilcrafts (free samples?), bootstrap snubber (<$1).
Did the Coilcrafts make a difference?
A 3.3uF film cap on the input might be worth it. Just bypass the on board SMT's with a solder blob or wire and put caps outboard at input terminals.
All Sanwu input ceramics are 4uF here. Inductors "100", 10uH to 14uH, total pvcc 1178uF/1352uF, not the TDK inductor lookalikes here.
Very low level hiss both, almost none, but gain might be 10dB when set for 32dB on ampboard I had connected yesterday, maybe one defective 330uF ? Treble seemed most lacking. Todays second board seems more powerfull maybe like 26dB gmarsh3118. Topmarked chip switching at 384kHz, centermarked chip (10dB board) 403kHz.
Voltagedrop diode with backgroundlevel music playing: 0.225V, turning up volume a little jumping with bass around 0.325V (slow dmm)
Very low level hiss both, almost none, but gain might be 10dB when set for 32dB on ampboard I had connected yesterday, maybe one defective 330uF ? Treble seemed most lacking. Todays second board seems more powerfull maybe like 26dB gmarsh3118. Topmarked chip switching at 384kHz, centermarked chip (10dB board) 403kHz.
Voltagedrop diode with backgroundlevel music playing: 0.225V, turning up volume a little jumping with bass around 0.325V (slow dmm)
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Nice antennas @trashcanz. 😉 You wanna snubber "HF" then make the current loop as small as possible.
For your own safety please make sure, your primary leads (power supply) are double isolated and separated from all secondary leads. 🙂
iribeo, why do you think one 330uF is defective and how does this corresponds to gain-loss?
Possible failures are "open-mode" or "short". First doesn't affect PVCC, second should trip the power supply.
For your own safety please make sure, your primary leads (power supply) are double isolated and separated from all secondary leads. 🙂
iribeo, why do you think one 330uF is defective and how does this corresponds to gain-loss?
Possible failures are "open-mode" or "short". First doesn't affect PVCC, second should trip the power supply.
Yes makes more sense if all 4 are bad, or were after 45 minutes powered ??? Today removed from Sanwu they measure 291uF 160mOhm, 298uF 302uF and 304uF all 140mOhm, can't really be reason, meter isn't real good could be 4kHz or 72kHz or averaged I don't know, good enough for indication. This board also ran a little warmer yesterday than board playing today, and much lower level, not cap related it seems. VT printed type, 8mm dia can, not datasheet 10mm like mentioned befor by other, chinese datasheet seems mix between Chemicon ripple and Nichicon layout including same letters and tables, including ripple multiplyer
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This "high" ESR seems "fine", as they aren't really low ESR as seen from the datasheet. (VT or RVT caps I guess?)
10dB sounds weird, hooking up a scope would tell or a stimulus frequency a normal multimeter can read properly like 100Hz. (If not TrueRMS)
Calculate back and we know exactly.
You could also check for capacitors leakage current and calculate ESR from rated tan delta.
I collected the datasheets here:
http://www.360customs.de/en/2016/04...ien/#Chang-Huawei-Electronic-8211-VT-8211-SMD
10dB sounds weird, hooking up a scope would tell or a stimulus frequency a normal multimeter can read properly like 100Hz. (If not TrueRMS)
Calculate back and we know exactly.
You could also check for capacitors leakage current and calculate ESR from rated tan delta.
I collected the datasheets here:
http://www.360customs.de/en/2016/04...ien/#Chang-Huawei-Electronic-8211-VT-8211-SMD
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If you're in a modding mood, try putting a big cap bank in parallel with your power supply/amp input. I have 4x5600uF on mine. I can't say if it improves the sound, but it does keep the music going a good 8--10 seconds after mains power is cut. Yeah, no real practical value there, but for some reason I continue to be amused by it. 😀
Ok "yesterdays" Sanwu loud now too, other electrolytics and wanted to replace inductors so took them off and then couldn't find the inductors I have in this size so soldered them back on, little ampboard does get real hot desoldering and soldering inductors with two soldering irons, so heat might have done something else
Irribeo,
I am lost - what are you talking about when you say you are testing caps and all this stuff in precious few posts? Is there a photo of what you are doing?
I am lost - what are you talking about when you say you are testing caps and all this stuff in precious few posts? Is there a photo of what you are doing?
Thanks X- I will try wiring a switch on the mutes. I am also planning on changing the power caps with some OSCON’s. Is it best to use the same value as the originals?
I am not testing caps. I had 1 watt sanwu 3118pbtl ampboard with maximum 10dB gain, where passive pot needed to be at 16:00 to give decent listening level, 17:00 being max volume position and gain set was standard, 100k/39k=32dB, cdplayer source over 2Vrms output into 10k pot. So the board was a little lifeless LOL
Sounds pretty defective. In theory, 20dB is lowest gain possible upon start up the ADC reads voltage form divider resistors to set gain. 10dB is not even an option from the allowed gain steps so it's messed up internally.
Like I said power output normal now. Most likely cause to me bad soldered inductors somehow, but also measured some things from bootstrap cap to output yesterday, over inductors, don't understand that didn't seem way off, but works ok enough now, just low impedance check left and then some soldering fun. Inductors are not very close to 10uH, heat increased the only 10uH that was on Sanwu's to 13uH, so now 30% and 40% off, lets see what happens with couple of ampères through them with low impedance speakers🙂
Would have been nice if you had done some measurements noted and shown to see/show what were wrong and now is most likely fixed.
16:00 vs 10:00 vs 17:00 pot level setting is nothing really valid to know a signal level. 🙁
How did you calculated/measured the 10dB?
16:00 vs 10:00 vs 17:00 pot level setting is nothing really valid to know a signal level. 🙁
How did you calculated/measured the 10dB?
I am switching ampboards, powersupplies and ampboards again and I can't get protection to trip on Sanwu's when others trip, I quit at over two times the Vac to electrostatics paralleled by dynamic sub, twice the voltage that was shown when dugs muted. I can't get dugs to protection mute on just electrostats, but connecting bass in parallel to electrostats I can easily trip protection dug's 3116 PBTL, over two times higher volts on dmm and Sanwu's do not mute, they do loose all bass btw, the dugs do not. But dugs have 10% Ldrop inductors at 36 ampères here, the chinese inductors, well they must saturate completely befor dug protection trips. Electrostat's impedance drops to 1.5 ohm mid/treble or close to that, maybe little lower, when woofer is connected in parallel that gets even lower.
(audiobah ac1308 mutes at less than 1/3th of Vac to combined electrostat/sub)
(audiobah ac1308 mutes at less than 1/3th of Vac to combined electrostat/sub)
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Good tip, just added a short over outputs and amplifier continues playing at recessed level, no protection
edit: but it does start to trip when I turn up volume knob towards max, so does have protection, isn't just as silent as on the other amps, there is a little crack accompying the mutes and unmutes, but never tried shorting the others, maybe the crack too then
edit: but it does start to trip when I turn up volume knob towards max, so does have protection, isn't just as silent as on the other amps, there is a little crack accompying the mutes and unmutes, but never tried shorting the others, maybe the crack too then
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Not tripping at low levels is normal behavior, as rms current isn't high enough and limited by inductors DCR.