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One step closer. Connected a cathode current meter to the tubes. Measured about 40mA. Then the current started to rise on V3 and V4 to about 50-55 mA. The pop sound came and the cathode current dropped to about 40mA. After a while it rose again and the same thing happened. V1 and V2 were normal.
Having a strange problem with a Marshall JMV410H. At irregular intervals there is a pop sound. The sound is the same as when you switch off the standby button. Like a small pistol shot, but with a silencer. Several minutes may pass between each time it happens. All volume controls are set to...
I will take a look at the tubes. To make it clear. I changed first the two catode resistors and then a put in the new tubes. i will also check the screen resistors.
I have changed the 4 power tubes and also the two cathode resistors with the same value but as 3W. One was burnt. Have also adjusted the bias to approx. 45mA for each tube (pair). Might try to test with one by one of the old pipes to see if that helps.
I run a small service workshop for electronics, especially tube amplifiers.
I have received a Marshall JVM410H which emits a pop sound in a non-linear pattern. There may be pop sounds at 40 second intervals or it may take up to 5 minutes before the sound comes. The sound does not depend on the...
Thanx. I will check the voltage loss and the ESR. And will use a variac to check the curent. I also uploaded a picture in higher resolution. I understood that the owner would like to have the amp so close to the original as possible.
Hi
I have a Marshall Super PA 100 with serial number to check for a customer.
For me it lokks like there are original capasitors in the amp. See pictures. Is it necessary to change this capasitors? There are no leakage or "bubble" .
Hi
I got an amp Marshall 2203-1 with effect card from a customer who has burned. As you can see at the attached pictures it is R31/32 in the filament system, and R17/18/20 in the feedback/cathode of the phase inverter tube, and R11 the cathode resistor at V2, the second valve in the preamp witch...
Thanx for lot of tips. i will try some of them this week-end and report back the result.
@neikeel asked for what happened . The owner told me that he tried to adjust the bias, then he short-circuited two pins on one of the EL34.
@Ray Baker. I am using a variac with ground between the wall and...
Hi everybody.
I hope that somebody can help me thinking. I have looked at this amp for a while, and I have problem thinking rationally. I have uploaded a video who explain the problems with the amp. I think it is a grounding problem, I have checked all point of soldering, twisted the filament...
Yes. I have also a suspicion about ground, but it looks like every groundpoint is ok.
I have changed the preamp tubes. No difference
When I remove the first preamp tube, the noise is almost gone.
Even when the guitar volume is totally down, the noise is still the same.
Help!
I have a Marshall JCM 800 who are rather noisy at High input. I post a video here where you can hear the noise when I put in the guitar at high input. I have tried with 6,3 DC filament for the two preamp tubes, no result. I have change the jack input set at the front. In the video you can...
Hi.
I wonder if I have the right diagram, because there is a effectloop printboard in the amp. I put a picture inside the amp. I also put a video about the noise when I connect a guitar to the High input. Also there is a vlip from the scope at the end of the video. The probe is connected to...