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Old 17th March 2009, 01:11 PM   #11
diyAudio Member
 
Join Date: Mar 2004
Location: Krakow
Default schematic too

Hi
sorry guys to be slightly offtopic,
I just need a schematic of a combo Kustom Arrow 16,
and would not set new thread for it,
could anybody help?
please,
Thank you in advance!
P
__________________
regards, Pawel
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Old 28th March 2009, 09:27 AM   #12
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Default Also Need AVT20 Schematic

Hiya

May I please request a copy of the Marshall AVT20 schematic? I am newly registered here and so am under surveillance or some euch thing...
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Old 29th March 2009, 08:46 PM   #13
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once you can use the email button email me and I will send you a copy
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Old 30th March 2009, 01:56 PM   #14
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Hi


Thank you for your kind offer. I found an earlier thread where somebody requested and received a schematic for a similar amp (Marshall AVT 50) so I e-mailed the replier in that thread and received the schematic from them (thanks tmenzo!).

Could I ask an opinion on a possible mod to the AVT20? I find that the amp is very shrill at higher volumes, what would be the component(s) I could change in the tonestack to help the situation?
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Old 30th March 2009, 01:56 PM   #15
krizza is offline krizza  United States
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Default Me too need AVT20 schematix

May I also get Marshall AVT20 schematic? I am too under moderation...
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Old 2nd April 2009, 06:54 AM   #16
Enzo is offline Enzo  United States
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Location: Lansing, Michigan
It never ceases to amaze me the memory of the internet. I posted about having certain Marshall schematics several years ago on this board and I still get several requests a week for them.
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Old 3rd April 2009, 02:27 AM   #17
eweege is offline eweege  United States
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Default AVT 20 R53 burnt resistor

Please count me in too. I tried emailing to "doctor" but can't email yet as I am still in "moderation" mode.

I need a schematic for the AVT-20. I found a burnt resistor at location R53. The problem I was having is that the amp was motor-boating when turned on.

Anyone have any ideas on a) what caused the resistor to overheat, b) where I can find an R53 replacement resistor, and c) where I can find a replacement metal post for one of the speaker wires to connect to? One appears to have snapped off during as I was removing the amp board assembly.

Thanks in advance.

Regards,

Eric
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Old 3rd April 2009, 08:04 PM   #18
eweege is offline eweege  United States
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Default Is the R53 Resistor on AVT-20 same as AVT-50?

I found a schematic for the AVT-50 but not for the AVT-20 yet (still in moderation mode). The AVT-50 shows R53 as being a 22k ohm resistor (1/4 watt?). Does anyone have any root-cause experience for these blown resistors and/or know how similar the schematic circuitry is between the AVT-20 and 50? I guess I'll check for any other blown/shorted caps, diodes, ICs, etc in the immediate R53 circuitry area while I'm waiting for email approval..

Thanks,

Eric
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Old 4th April 2009, 12:06 AM   #19
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the avt-50 schematic is DIFFERENT from the avt-20 by miles...the avt-20 schematic has a 10ohm 1/2 watt resistor in r53...according to the tda 2050 data sheet it helps prevent oscillation/feedback? c71 is associated with it ...c71 is .22microfarad ...when r53 toasted it melted c71 as well...I know for a fact that letting the amp feedback alot will toast this resistor.
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Old 7th April 2009, 10:56 PM   #20
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Hello Again

Would anyone care to make a suggestion as to how to make this little amp less shrill (see my post above). Would socketing the TL072 chips and trying different opamps there make any difference? How about the tonestack-is there any component changes that would help? Finally would changing out the 12AX7 for a 12AT7 or 12AU7 help matters any?

Thanks all for your time and efforts

earache60
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