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| [#21] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL THE measured output after the CAP ..is 28VDC ( not make sense as the input is 27 VAC......but ...) which suppose to connect to of heaters for all 3 tubes funny..... tube 1 : Pin 4 = 8 VDC . Pin 5 , zero VDC tube 2 : Pin 4 = 8 VDC , Pin 5 @ 18 VDC Tube 3: Pin 4 = 18 VDC , Pin 5 @ 28 VDC but..............tube 1 pin 5 ...@ zero V...whyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy, suppose there at alllllll connected.. whyyyyyyyyyyyyyy funnyyyyyyyy  最後修改時間: 2021-07-10 14:05:23 |
hahayanyan 正式會員49.xxx.xxx.237 |
2021-07-10 13:58 | |
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| [#22] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL In your circuit, the filament of each tubes are connected in series. Ideally, you have to supply 37.8VDC (12.6V x 3) or 37.8VAC (rms) to them. Now that your AC input is 27VAC, don't expect rectified DC to be somewhere near 37.8VDC (27*1.4). The rectified DC is a varying direct current with peak approximately 37.8V. When you measure DC voltage, it's much lower as your meter gives you average value (not the peak value). After pi filter, your DC is much stable and its value is closer to the average value measured before filtering. Normally, you will get rectified DC with value slightly higher than the input AC. It's assumed it's capacitor-input filter and with loading. The value is much lower with choke-input filter. I think it's normal you get 28VDC out of 27VAC input |
bambino 正式會員 123.xxx.xxx.161 |
2021-07-10 14:51 |
| [#23] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL Almost understood fully on what u jsut taught me Things I do not understand... If it is really series... Why pin5 tube one no voltage.. Haha Hard for my skill level to trace the circuit from that double side pcb... Haha.... Am trying for the low voltage path Thx thx thx |
hahayanyan 正式會員 49.xxx.xxx.119 |
2021-07-10 15:02 |
| [#24] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL tube 1 pin 5本來就接了地，當然是零，對嗎！？ |
羅密歐 正式會員 218.xxx.xxx.140 |
2021-07-10 15:04 |
| [#25] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL #24 係喎接咗地... 簡單的提醒thx Pin 4 and 5 is series... Abd pin 5 to pcb ground having lower reistance vs pin4 to pcb ground point 繼續學習 form basic.. Haha每日喝多一點點 最後修改時間: 2021-07-10 15:12:57 |
hahayanyan 正式會員 49.xxx.xxx.119 |
2021-07-10 15:08 |
| [#26] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL referring to your schematic below, the filaments are connected this way.... Gnd -＞ Tube 1 (Pin5) -＞ Tube 1 (Pin4) -＞ Tube 2 (Pin4) -＞ Tube 2 (Pin5) -＞ Tube 3 (Pin4) -＞ Tube 3 (Pin5) -＞ 28VDC Note the order of pin numbers, tube 1, pin5 is measured 0V against Gnd.  |
bambino 正式會員 123.xxx.xxx.161 |
2021-07-10 15:11 |
| [#27] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL Haha thx guys Seem the filament circuit seem fine Then I troubleshooting the HV 最後修改時間: 2021-07-10 15:16:42 |
hahayanyan 正式會員 49.xxx.xxx.119 |
2021-07-10 15:15 |
| [#28] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL 現在可以經計算得知，各膽之燈絲電壓如下， Tube 1 = 8V Tube 2 = 10V Tube 3 = 10V 而本來應該是每支膽都是12.6V的。 很不正常啊！ 尤其是tube 1的陰極，根本不可能在正常工作溫度。 另找三支燈絲電阻一致的膽來調試吧。 |
羅密歐 正式會員 218.xxx.xxx.140 |
2021-07-10 15:16 |
| [#29] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL Ok... I find some better match tube.. Good learning today.. Remind me.. 3 filament actually just 3 simple voltage divider.... Thing should added up to be the same as the first input Pin 5 of tube one to pcb ground does having some resistor and cap on the pcb I do feel strange too..i do suppose to see 6.3x6.... Haha thx thx rhx thx 最後修改時間: 2021-07-10 15:23:32 |
hahayanyan 正式會員 49.xxx.xxx.119 |
2021-07-10 15:18 |
| [#30] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL if you want to supply the rated voltage to filament of multiple tubes, it'd better connect them in parallel. this way, each filament current might be different but are powered by the same voltage. most tubes are designed to operate at the rated filament voltage. 最後修改時間: 2021-07-10 15:37:31 |
bambino 正式會員 123.xxx.xxx.161 |
2021-07-10 15:36 |
| [#31] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL now having 3 tube...the filament resistance all around 36 ohm ( it was...one of them at 55ohm, and 2 at 36 ohm) tube 1 : Pin 4 = 10.7 VDC . Pin 5 , zero VDC tube 2 : Pin 4 = 10.7 VDC , Pin 5 @ 20.78 VDC Tube 3: Pin 4 = 20.77 VDC , Pin 5 @ 28.9 VDC closer. match ..haha #30 that is not the scope today......, but it is a very logical thought toooooooooooo 最後修改時間: 2021-07-10 15:40:51 |
hahayanyan 正式會員 49.xxx.xxx.119 |
2021-07-10 15:37 |
| [#32] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL Tube 3燈絲電壓還是太低了，只及正常的65%。 量燈絲電壓，不用對地來量。以你面前這台機為例，一對表針直接跨在pin 4與5之間便可。 |
羅密歐 正式會員 218.xxx.xxx.140 |
2021-07-10 15:48 |
| [#33] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL still, tube 3 got 8.13V on filament, way too low against rated voltage 12.6V overall, the filament supply voltage is too low (28V). and also, power trans secondary is 110VAC only. be honest, i don't understand why it has to step down input AC 220V to 110V and later on boost back up to 2xx volt (via voltage doubler or something). i think it's something weird in the circuit design. the circuit in #2 makes more sense. |
bambino 正式會員 123.xxx.xxx.161 |
2021-07-10 15:50 |
| [#34] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL #32 tube 1 between pin 4 & 5 : 10.69 VDC tube 2 between pin 4 & 5 : 10.1 VDC tube 3 between pin 4 & 5 : 8.13 VDC the actual circuit on the board is a combination of #2 and #20 ,and some add on coupling cap and transistor Filament circuit..follow mostly from #20, actaul on pcb having some coupling resistor and cap to pcb earth HV - follow mostly # 2 ... some add on around the plate input ... haha may be it is some sort of secret sauce to get a tone inbetween a 6922 and 12AXT type of sound..haha...who knows..haha..., the plate seem running cold too. haha so lucky..one of the seller...said..he could not sell me a not working R2R..even he committed..haha...,...although i love that.., but should not take more haha 最後修改時間: 2021-07-10 16:03:01 |
hahayanyan 正式會員 49.xxx.xxx.119 |
2021-07-10 15:51 |
| [#35] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL 燈絲供電電壓不足，可以減小#20中的R16阻值來調整。 現在的麻煩是，三只12AX7的燈絲阻值不一致，這就比較奇怪了。就算用平價的國產膽，我也未嘗遇到過誤差這麼大的。 最後修改時間: 2021-07-10 18:39:39 |
羅密歐 正式會員 182.xxx.xxx.98 |
2021-07-10 18:37 |
| [#36] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL 明白明白 但係這應該 有一個channel 無聲的原因 Haha... Shall further investigate it later.. Tonite Thxx |
hahayanyan 正式會員 49.xxx.xxx.255 |
2021-07-10 19:33 |
| [#37] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL 一係就支膽死 係咪三支同係新既12AX7? 定係有d 用左5751? |
schmike 正式會員 123.xxx.xxx.143 |
2021-07-10 20:58 |
| [#38] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL 佢好似會整死啲tube Haha 其實對上兩次都玩put 啲一定冇事嘅tube.. Haha They are all 12ax7 on it.. And very certain they are ok too (was) Not sure.... I have some more not expensive ax7 around surely they are functional I have only 3 to 4 pcs of not too bad 5751...notngoing to risk it.. Haha 最後修改時間: 2021-07-10 21:51:50 |
hahayanyan 正式會員 49.xxx.xxx.40 |
2021-07-10 21:51 |
| [#39] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL Haba no idea why... One chanel no sound But quite sure.. One of the transistor is bad.. At be o e of the diode too |
hahayanyan 正式會員 49.xxx.xxx.79 |
2021-07-12 18:55 |
| [#40] Troubleshooting:CLONE Ear 834P LOST LEFT CHANNEL Haha 我相信佢應該燒咗笠regularator Haha But I may also damage the bottom trace when remove that regulator...2 of the bottom side do not have conductivity to the top trace  最後修改時間: 2021-07-15 12:56:29 |
hahayanyan 正式會員 49.xxx.xxx.105 |
2021-07-15 12:52 |
