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  1. Replies
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    got those caps in and managed to get the amp to...

    got those caps in and managed to get the amp to behave for 4hrs. I replaced the 2 main filter caps. After 4 hrs the bias was at 85mv each side. Still not sure I fixed it, as it still rose over time...
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    Haha I know Enzo... I don't care about the...

    Haha I know Enzo... I don't care about the 315v... it's more the SIZE. 330uf 350v with the 10mm lead spacing and 20mm diameter is what's difficult. Marshall did not allow for larger radial caps. I...
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    Don't have the signal generator either, but can...

    Don't have the signal generator either, but can probably make this happen in the coming days.

    I am replacing the bulging main B+ caps. 330uf 315v. They are 20mm diameter and 10mm lead spacing. ...
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    So at power on, had nothing. After about 40...

    So at power on, had nothing. After about 40 minutes, the hum is loud, and there is about 60mvDC using the diode/cap. It's a bit odd, if I set my meter at 6v it reads 500mv... if I set it at 600mv...
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    Lemme answer my own question. The smallish cap...

    Lemme answer my own question. The smallish cap won't register lower frequencies. This will only yield rectified high freq. :p
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    As always Enzo thanks for the help. Wouldn't...

    As always Enzo thanks for the help. Wouldn't this just show ANY noise the amp produces? IE If there's hum anywhere in the amp that's being amplified to the output, wouldn't that show as DC voltage...
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    Unfortunately due to circumstances my scope is...

    Unfortunately due to circumstances my scope is not available at the moment.

    I removed C46 altogether.

    Running a mains current test now... at power on it's sitting at 1.16A. Seems very...
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    This was happening before I removed C46... and...

    This was happening before I removed C46... and after. I am just now recalling all the tests I ran on this amp months ago. Usually I have notes on these things... but have been out of the routine.
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    Agreed.. BUT, now I am back to where I was...

    Agreed.. BUT, now I am back to where I was before... months ago. I took a break from this amp cause I couldn't figure it out.

    I put it back in the cab and it is now running away really bad... I...
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    Thanks guys... Leo.. I should have mentioned...

    Thanks guys...

    Leo.. I should have mentioned that mod has already been done but did not fix the bias drift. It truly seems as though removing C46 fixed it. Odd.
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    Oh I didn't know that.. what is the issue with...

    Oh I didn't know that.. what is the issue with C46 if it's not the bias drift?

    Also, do you have any tips on drift?
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    I may have found a fix for drifting bias in these...

    I may have found a fix for drifting bias in these amps. Tomorrow will be the true test. I found another forum where someone mentioned C46. This cap is across V8 EL34 Plate-screen. My guess is it's...
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    Okay gotcha, thanks

    Okay gotcha, thanks
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    Thanks guys... Hem I didn't say anything about...

    Thanks guys... Hem I didn't say anything about 15% below so not sure where you got that figure from.

    Customer says amp isn't as loud as it was before. Typical haha... so we are trying to measure...
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    G1 are Music Man amps truly what the stated RMS...

    G1 are Music Man amps truly what the stated RMS wattage is? It'd be the first amp company I know of where this is the case. IE a 100W Twin Reverb does not put out 100W of clean signal with no...
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    Additionally: It can't be an oscillation, because...

    Additionally: It can't be an oscillation, because upon pulling the PI, the bias slowly goes back down, about .1ma every 3 seconds. Quite strange... I can't think of anything that could cause this. ...
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    Hey folks.... got one in with this problem. It's...

    Hey folks.... got one in with this problem. It's a TSL 122. But as mentioned early on in this thread... the bias only drifts (high) if the phase inverter is in place. Which leads me to suspect an...
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    Samsung lns3251d overscan

    Hey all,

    Anyone know why this happens or how to fix it?

    I have a Mac mini connected via HDMI to the TV in the subject. Everytime my Samsung sleeps, the aspect ratio on the TV gets messed up. ...
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    Thank you sir! I've been on a real estate...

    Thank you sir! I've been on a real estate investing adventure for the last 1.5 yrs so haven't been doing as much amp work. Still love audio electronics though! And this forum is incredible... love...
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    Lifted the anode of the bias diode, removed the...

    Lifted the anode of the bias diode, removed the 120k dropping resistor, floated the junction of the two, ran a floating wire to the 33k/15k junction. Fixed. Conductive board.
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    Lifted the anode of the bias diode, removed the...

    Lifted the anode of the bias diode, removed the 120k dropping resistor, floated the junction of the two, ran a floating wire to the 33k/15k junction. Fixed. Conductive board.
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    Cheap pcb boards, bad design. I had this issue...

    Cheap pcb boards, bad design. I had this issue in this thread from a while back. https://music-electronics-forum.com/showthread.php?t=43711&highlight=mesa+rocket

    I now have the same model amp on...
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    I have another one of these on my bench. Guess...

    I have another one of these on my bench. Guess what the issue is. Yep, the same. This is not the same amp I worked on before, it still has the stock 120k resistor in the bias supply. I'm still...
  24. Thread: Crate BX50 DLX

    by lowell
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    Thanks guys... I'll skip replacing all those...

    Thanks guys... I'll skip replacing all those components then for now. I already checked opamps for DC offset.

    Not a speaker issue... forgot to say I tried others
  25. Thread: Crate BX50 DLX

    by lowell
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    Crate BX50 DLX

    This came in with a blown TDA output chip. Replaced it and now it's working, however it has a gated/farty distortion thing going on. It's even worse on the lead channel. So it's common to both...
  26. Thread: TDA2050

    by lowell
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    Thanks for the help guys and sorry for the late...

    Thanks for the help guys and sorry for the late reply! haha
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    Yup thanks.. they're plastic jacks anyways

    Yup thanks.. they're plastic jacks anyways
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    He misspoke :D Happens in and out of chassis

    He misspoke :D

    Happens in and out of chassis
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