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Old 25th September 2012, 02:43 AM   #31
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Interested
Lets see what the schematic looks like.

sdman
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Old 14th November 2012, 02:05 AM   #32
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Default L7 Amp

I too have bought the kit and have reversed engineered the schematic. I'd like to compare mine with others. What is the verdict on sharing?

I'm using the L7 to replace a blown power amp in a Janis Interphase 1A subwoofer amp. I'm almost ready to power up. I'd like to cross check my schematic before doing so. I plan to power up slowly using a variac, but am not sure what to look for on the output mosfet voltages. i.e. if they were bipolars, I know I can watch for the Vbe's to come up to 0.7. Any tips?
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Old 11th January 2013, 01:37 PM   #33
exflaco is offline exflaco  Armenia
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Please share complete L7 schem and pcb
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Old 11th January 2013, 02:28 PM   #34
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Quote:
Originally Posted by exflaco View Post
Please share complete L7 schem and pcb
Nice small Amp, sch. & pcb 2.

Regards zeoN_Rider
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Old 5th March 2013, 04:44 AM   #35
ljm_ljm is offline ljm_ljm  China
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Quote:
Originally Posted by skipt View Post
I too have bought the kit and have reversed engineered the schematic. I'd like to compare mine with others. What is the verdict on sharing?

I'm using the L7 to replace a blown power amp in a Janis Interphase 1A subwoofer amp. I'm almost ready to power up. I'd like to cross check my schematic before doing so. I plan to power up slowly using a variac, but am not sure what to look for on the output mosfet voltages. i.e. if they were bipolars, I know I can watch for the Vbe's to come up to 0.7. Any tips?
VGS. They and BJT similar measurement. First, the first in a pin the voltage.
Usually have a 3.3 V - 3.6 V, N - MOSFET, P - MOSFET voltage is different.

Generally I suggest that need not adjust L7 above values.
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Old 10th March 2013, 11:29 PM   #36
rade95 is offline rade95  United States
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Why nobody published the schematic?
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Old 18th March 2013, 12:55 AM   #37
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Default double output stage

Hi LJM.
I purchased this amp kit from Ebay. The amp board is very good quality and I have assembeld and tested for basic operation with no heatsink (+-/ 35 v, 10 ohm in series with supply rails. Both modules worked first time. I would like to add a second pair of output fets to increase the output current ....Is this possible. The aucton states:
Class AB MOSFET L7 Audio power amplifier boards KIT DUAL-CHANNEL 300-350W X2 NEW."

I dont think in this configuration it can handle 300w RMS. My supply rails will be +/- 74DC. Could I safely add the second set of fets? Should I add 2 sets??

Thanks
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Old 21st March 2013, 02:44 PM   #38
rade95 is offline rade95  United States
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Hi LJM_LJM,
Just got my boards and started examining the circuit. There are several problems with the components marked on the PCB. First the PCB is NOT desigbed for IRFP9240/240 because if IRFs were used the PCB would connect two source pins of the MOSFETs. Look at F5 PCB and you will see what I am talking about. F5 PCB connects middle pins of the IRF MOSFETs which are drains not sources. If you use Toshiba K1058/J162 lateral MOSFETs (probably a better choice anyway) the pin layout IS CORRECT. Next in the driver stage there are 2 2N5551 close together. The pin layout of 2N5551 like 2N5401 is EBC looking at the flat front of the transistor. However the PCB layout for 2N5551 drivers has middle pins connected, if they are BASE this makes no sense. Looking at the schematic in post #5, 2N5551 drivers have COLLECTORS connected indicating that the pin layout is ECB not EBC, which for 2N5551 is _wrong_. I don't know if there are any suitable transistors that would match ECB pin layout. I can bend the pins and fix that but why was this done? I don't get it. A mistake of the PCB designer I guess. The bigger problem is that the PCB and the IRF MOSFETs supplied do not match the pin layout of the IRFs, so there is no way on Earth that this PCB would work with the IRFs without modifying (cutting) the PCB pads. For the sake of making this kit buyers happy, LJM_LJM can you please comment on this.
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Old 21st March 2013, 05:32 PM   #39
rade95 is offline rade95  United States
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I tested the transistors and now I can confirm that 2N5551 supplied with the kit DO match the PCB layout ECB. They are not EBC transistors like you buy on Mouser or Digikey. This is strange, very strange.
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Old 22nd March 2013, 02:07 AM   #40
rade95 is offline rade95  United States
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Quote:
Originally Posted by Tinface View Post
I bought a couple of kits, reverse engineered the PCB and have created schematic. Should I publish here?
Please PM me and lets exchange schematics. Have you finished building your amp?
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