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IF you do indeed have continuity from V5 pin 2 & pin7 to V4 & V3, pin 4/5 & 9, then you cannot explain the lack of voltage on V4 & V3.
Something is not being measured correctly.
Something is not being measured correctly.
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Or maybe the continuity is failing only when current is flowing?Originally posted by Enzo
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It's not that difficult of a circuit.
The heaters are in parallel.
Like stacked up checkers.Comment
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"Typical" heater circuit for reference."I took a photo of my ohm meter... It didn't help." Enzo 8/20/22Comment
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Could be corrosion, a bad solder connection, break in the wire inside the insulation, jumper s wire between those two points.Comment
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Correction********Originally posted by sweatyk View Post
V3 & 4 read 7.28VAC across pin 9 and 5
Sorry for the false reading there Jazz P...........stressful week here.Comment
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Isn't 7.2 VAC a little too high for the heaters on V5 thru V8? Aren't they supposed to 6.3 VAC?Comment
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Is that with tubes in or tubes out? Tubes out, it should drop when they're in. Tubes in, yeah, that's high... I guess if tubes aren't regularly burning out, though, it's okay... the Super Twin I had for a while didn't eat the tubes with 7.1V. Seems +\-10% is allowable for spec.
JustinLast edited by Justin Thomas; 03-08-2015, 05:55 PM."Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
"Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
"All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -Comment
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That's par for the course with no tubes in. All your voltages will be higher, with nothing to pull the current.
Justin"Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
"Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
"All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -Comment
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Well the symptoms have somewhat changed since the beginning of this thread and I cannot figure out why. All I have done is clean and tightened the tube sockets, reflowed solder, and take some voltage readings. I have inspected the main board under a magnifier a dozen times looking for incidental solder bridges and cracked traces. When I first got it only 3 of the 4 power tubes would light up other than the lighted power switch itself. Now none of the tubes light up and the power switch flickers when I turn it on then goes out. I have tried different tubes. I ran jumpers from the power tube sockets pin 2 and 7 to the tubes not installing them and they light up just fine. Quite frankly I’m a bit baffled. I would really like to repair this but my knowledge of how circuits’ works is my weak spot. Any thoughts?Comment
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Have you resoldered all the sockets?Originally posted by Enzo
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yesComment
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You said the power tube flickers, is this the same or a separate issue? When you run the jumpers to the tubes, does the power switch now stay lit?
When you use the jumpers, I assume you only try one tube. How about when you only plug one tube into the socket, still no heater?
Edit: removed info that referred to wrong schematic.Last edited by g1; 03-09-2015, 06:36 PM.Originally posted by Enzo
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I looked them over several times on both side to make sure I didn't over do it. Deoxed and retensioned them all. What are your thoughts. I could always remove them completely and inspect. I'm guessing I should do that before I go any further.Originally posted by g1 View PostComment
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