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| [#2662] 回覆(40):Leaky cap? r Fingers got itches yestersday. Got out the NOS TCC caps got recently from UK. The Caps are packed individually, and look pretty NOS. |
clng2003 正式會員61.xxx.xxx.22 |
2004-08-22 08:29 | |
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| [#2663] 回覆(40):Leaky cap? r Intention was to post the pic for the NOS caps, can't get to work. Perhaps you can tell me how to begin my story. |
clng2003 正式會員 61.xxx.xxx.22 |
2004-08-22 08:32 |
| [#2664] 回覆(40):Leaky cap? Chi, Use MSN photo server, of which the address assigned is static and can work in R33. http://groups.msn.com/ Log in MSN and create a MSN GROUP. Post your photos in the GROUP's 'pictures' folder. Bingo!~ r |
rcwy 正式會員 221.xxx.xxx.250 |
2004-08-22 08:57 |
| [#2665] 回覆(40):Leaky cap? r This is the TCC Caps from UK. It appears NOS. |
clng2003 正式會員 219.xxx.xxx.71 |
2004-08-22 12:26 |
| [#2666] 回覆(40):Leaky cap? r. Try onc more than for upload.  |
clng2003 正式會員 219.xxx.xxx.114 |
2004-08-22 17:07 |
| [#2667] 回覆(40):Leaky cap? r The picture upload seem OK now. I can begin my tale. Next, I changed all four C4 & C6 caps (0.25uF) and C3 (0.1uF). After completion, I checked the voltage and note the following results.  |
clng2003 正式會員 219.xxx.xxx.114 |
2004-08-22 17:12 |
| [#2668] 回覆(40):Leaky cap? r Two things seem strange. First, the voltages before C6 (both left and right) appear 134 and 146v when compared with the voltages before C4 at 230 and 220v. Voltage per spec. is 220 and 215v (C4 and C6). These measurements are taken before the newly installed 0.25uF caps. This coudl be nothing to do the TCC caps. I swear the voltages were OK before before the change. Secondly, the voltages at pin 8 of the KT66, all showing very much higher voltages 36 to 41v (spec. voltage 29v). Somethings seem pretty wrong. Could it be leaking caps. How do I verify. The ST60 is now idle waiting for diagnosis. As the last resort, I will put back the Jensen Caps. I am now curious to know are the caps leaking? since I got quite a few spare one from the same seller, I need to find out. By teh way, with teh jensen, all pin8 voltages (all 4 KT66) are all close to 29v. Chi |
clng2003 正式會員 219.xxx.xxx.114 |
2004-08-22 17:27 |
| [#2669] 回覆(40):Leaky cap? Chi, Just back from Michael (Mung)'s place shortly. Let me download the circuit diagram tomorrow and digest what you meant below. r |
rcwy 正式會員 221.xxx.xxx.250 |
2004-08-23 00:13 |
| [#2670] 回覆(40):Leaky cap? I can begin my tale. Next, I changed all four C4 & C6 caps (0.25uF) and C3 (0.1uF). After completion, I checked the voltage and note the following results. ------------------------------------------------------------ Chi, You must be waiting for some feedback. First of all, I cannot read any detailed figures from the schematic that you posted below. Resolution is too low (picture too small). Anyway, I'll judge from what you said in the next message. r |
rcwy 正式會員 221.xxx.xxx.250 |
2004-08-23 00:29 |
| [#2671] 回覆(40):Leaky cap? Chi, I have just printed a schematics to understand what does it mean by C4, C6, etc. "Two things seem strange. First, the voltages before C6 (both left and right) appear 134 and 146v when compared with the voltages before C4 at 230 and 220v. Voltage per spec. is 220 and 215v (C4 and C6). These measurements are taken before the newly installed 0.25uF caps." What you refered to are the plate voltage of V2a an V2b and the value is affected by R7 and R10 AND the respectively internal impedane of V2a an V2b. First, have you accidentally swopped V2(Left) with V2(Right), or with other 12AX7 tubes? Different tubes have different aging condition and therefore different internal impedance. Second, check the condition of C3 and C5! If these two coupling caps are leakage, they will respectively affect the biasing of V2a and V2b and will hence change the internal impedance of V2a and V2b. I suspect these are the culprit. Third, check if R6 and R11 have drifted in value too much which will also affect the biasing of V2a and V2b. "Secondly, the voltages at pin 8 of the KT66, all showing very much higher voltages 36 to 41v (spec. voltage 29v)." Obvious signs of DANGER of the four expensive KT66 tubes! Each was runing at 82mA to 93mA!!! According to the schematics, 29V means 65.9mA each KT66 only! Running at 93mA means the KT66 will die in a couple of days or weeks. "Somethings seem pretty wrong. Could it be leaking caps. How do I verify. The ST60 is now idle waiting for diagnosis. As the last resort, I will put back the Jensen Caps. I am now curious to know are the caps leaking? since I got quite a few spare one from the same seller, I need to find out. By teh way, with teh jensen, all pin8 voltages (all 4 KT66) are all close to 29v." C4 and C6 could be leaky. How to check. Use your DC meter with the red probe touches other lead of C4, and black probe touches ground (chassis). What is the DC voltage of this supposingly 'zero' potential grid (when no sign is in)? If the DC voltage is below 1V, there may be a very slight leakage and is usual for PIO caps. If the DC voltage is between 1V to 2V, attention is required. If above 2V, the caps should NOT be used any more. Of coures there are other, more scientific, means for testing any leakage of caps to test the leakage parameter at the rated voltage. Note: a cap does not show leakage at 10V does not mean it will be OK at 500V. Hope this helps you. Good luck! r |
rcwy 正式會員 221.xxx.xxx.250 |
2004-08-23 00:56 |
| [#2672] 回覆(40):Leaky cap? Chi, If there is other problem, feel free to post here. I have to go to have a shower and ZZZZZZZZZzzzz. Bye for now. r |
rcwy 正式會員 221.xxx.xxx.250 |
2004-08-23 01:01 |
| [#2673] 回覆(40):Leaky cap? thanks, Richard. The 93mA calculation, I figured out also. You showed me before last time you visited my home. I am still a bit unclear how to test the PIO caps, I will call you later on today, when you get out from your ZZZZZZZZZzzzz. Chi |
clng2003 正式會員 210.xxx.xxx.115 |
2004-08-23 08:43 |
| [#2674] 回覆(40):Leaky cap? Good morning! r |
rcwy 正式會員 221.xxx.xxx.250 |
2004-08-23 10:28 |
| [#2675] 回覆(40):Leaky cap? r Confirm by the voltage measurements taken at the output end of the caps, they read 4,3,8 and 8v for the four 0.25uF and 21 and 32v for the two 0.1uF first stage coupling caps. Too bad, I got quite a few from the same guy (from UK). It needs to be returned. for now, change back to the old trusted Jensen. Thanks for the help. Chi |
clng2003 正式會員 61.xxx.xxx.28 |
2004-08-23 21:32 |
| [#2676] 回覆(40):Leaky cap? Chi - Hope the seller will be cooperative la. r |
rcwy 正式會員 221.xxx.xxx.250 |
2004-08-23 23:38 |
| [#2677] 回覆(40):Leaky cap? http://home.mira.net/~kiewavly/TL25a.html Information about this amplifier is very limited as it does not appear to have been advertised to the extent that the TL/12 was. The units photographed here date from about 1953. Physically the TL/25A is on the same chassis as the TL/12 (the chassis is even punched for TL/12 components), however the output transformer is vastly larger in size - looking more like a 50 Watt transformer. Another physical difference is the addition of a sixth valve on the chassis between the output valves and mains transformer. It is likely that these amplifiers were built to order, rather than being available ex-stock, making them very rare.  |
Gingers 正式會員 221.xxx.xxx.208 |
2004-08-24 22:45 |
| [#2678] 回覆(40):Leaky cap? Gingers, I need your professional researching service. Could you point the link to a site with the schematics for the LEAK TL25A? I seemed to have it at some stage but couldn't find it now. r |
rcwy 正式會員 221.xxx.xxx.250 |
2004-08-24 23:27 |
| [#2679] 回覆(40):Leaky cap? Could you point the link to a site with the schematics for the LEAK TL25A? I seemed to have it at some stage but couldn't find it now. ------------------------------------------- Try http://www.vintage-radio.com/data/list/leak.shtml http://www.vintage-radio.com/index.shtml Perhaps no free lunch. John |
Gingers 正式會員 221.xxx.xxx.208 |
2004-08-24 23:43 |
| [#2680] 回覆(40):Leaky cap? http://www.burdaleclose.freeserve.co.uk/new_page_66.htm |
Gingers 正式會員 221.xxx.xxx.208 |
2004-08-24 23:44 |
| [#2681] 回覆(40):Leaky cap? http://www.burdaleclose.freeserve.co.uk/circuit_order.htm |
Gingers 正式會員 221.xxx.xxx.208 |
2004-08-24 23:45 |
