I think that's believable. Still pointing to the V1 stage as the problem. It would be handy to stick a spare 12AX7 (==ECC83) in right about now just to see what happens. It would not be the first cathode follower that I've seen fail due to excessively heater to cathode voltage. I recall you measured about 200V on the cathode (R19). The tube spec is 200V and some makes are better than others.
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I really don't know yet. We'll know more when the capacitor comes is. On the other hand do you know where you at least borrow one for a test?
Or buy one here https://www.thomann.de/it/jj_nn003_roehre_ecc83s.htm EU8.90 + shipping.Experience is something you get, just after you really needed it.
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Unfortunately Nobody can lend me one.But as soon as we test with the cap(I should get this week)will see I've found this in italy ECC83S JJ-ELECTRONIC 12AX7 ECC83 tubes tube valvole NUOVA TESTATA | eBay
is it the right one?
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I just checked the data sheet for the JJ's. The max heater to cathode voltage is 180V. Better go for a Sovtek 12AX7LPS ECC83 - 12AX7LPS SOVTEK VALVULA NUEVA NEW TUBE RÖHRE TESTED | eBayExperience is something you get, just after you really needed it.
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so guys finally I got the cap so If i understand I need my "signal generator" to check if the tube works.So can you please tell what i have to measure now?
P.s. for nickb
Since you like etna yesterday there was an explosion and 10 skiers where lightly injured(nothing serious) :-)
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Originally posted by AL78 View Postso guys finally I got the cap so If i understand I need my "signal generator" to check if the tube works.So can you please tell what i have to measure now?
P.s. for nickb
Since you like etna yesterday there was an explosion and 10 skiers where lightly injured(nothing serious) :-)
OK. Add the cap in series with your meter lead, either black or read it doesn't matter. Set up the signal generator test like before and measure the ACV at the junction of R9/R10, R20 where is connects to V1 anode & grid and R19 where is connects to V1 cathode. It would have been a big help if Marshall had bothered to put the pin numbers on the schematic for V1Experience is something you get, just after you really needed it.
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Hi thanks so I put my signal to 300mv I get 2.195v on the junction of r9/r10
So If I understand right I have to check the 2 points where there is continuity with r19 right?
Both point is 86v AC
Unfortunately for r 20 there is more than one point of continuity how can identify the right one?Last edited by AL78; 03-18-2017, 04:59 PM.
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Originally posted by AL78 View PostHi thanks so I put my signal to 300mv I get 2.195v on the junction of r9/r10
So If I understand right I have to check the 2 points where there is continuity with r19 right?
Both point is 86v AC
Unfortunately for r 20 there is more than one point of continuity how can identify the right one?Experience is something you get, just after you really needed it.
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