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M400t Repaire and upgrade

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tpsretard

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Joined: Mon Jan 19, 2009 10:12 am

Post Tue Jan 20, 2009 11:37 pm

M400t Repaire and upgrade

OK, i just got the first m400t working again
:) i miss the sound of a carver.

The dum op amp was faulty. Sending 25 volts across the speaker outputs.
so i replaced that with a spare i had nocking around from an older m400 that i keep for parts.

Now that the amp is running again i would like to bring her to the 21st century.
i want to change the outputs, and most of the filter caps and posibly the caps on the amp boards also.
maybe a better quality input opamp also.

have anyone here ever done this to an M400t or am i heading for uncharted waters..
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OBI56

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SILVER-7 TUBE AMP

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Post Tue Jan 20, 2009 11:55 pm

Re: M400t Repaire and upgrade

Congrats on getting the cube working again tpsretard. You are a brave man to want to start upgrading a cube; those things are a bitch to work on as there is practically no room to work in there. The most difficult part is going to be the PS filter caps as you have paper thin clearances as it is so you have to make sure that the replacement caps are no bigger than the originals or risk either shorting something or blocking the limited airflow in there. Not sure if anyone here has actually managed to upgrade a cube or not, but I'm interested in finding out how you fare.
Why let facts or common sense get in the way of your opinions.
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tpsretard

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Posts: 18

Joined: Mon Jan 19, 2009 10:12 am

Post Wed Jan 21, 2009 9:12 am

Re: M400t Repaire and upgrade

I do not know about brave, more stubborn than anything really.
Working on the amp cards are not that bad, if you damage the psu card, that is where it gets a little harder because of space.

Now this is the late model m400t where is uses a real opto cupler (transistor, not the older resistor) so i got a nice one :) YAY

i am going to replace the outputs.
C3000 = MJ15022/MJ15024
C5000 = MJ15022/MJ15024
C1100 = MJ15022/MJ15024

C1000 = MJ15023/MJ15025
C2000 = MJ15023/MJ15025
C4000 = MJ15023/MJ15025

I also want to replace some of the other transistors also.
MJE3055t = MJE15028 (if there is something better let me know)
MJE2955t = MJE15029

Now there are 2 other transistors that i am wonder if it is worth it to replace, i need them for another m400, but i am wondering if i should just wait to get a junker and rip them out. these are the old as hell Motorola MPSU10 & MPSU60.

I am going to replace all the electrolytic's on the amp board as they are small and easy to get, but i am not sure what is out there to replace the filter caps yet.

I would like some feedback on some of these parts people. i am really rusty when it come to working with audio as i have been head first into micro for a while..
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BillD

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(pair of) SILVER-7 TUBE AMPs

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Joined: Wed Jun 06, 2007 8:29 pm

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Post Wed Jan 21, 2009 3:22 pm

Re: M400t Repaire and upgrade

You can't get exact replacements for filter caps. There is a post somewhere on here that talks of the replacements. I worked on mine, and had to replace the fuse holder because the new caps were too long. Here's what I found.
  Code:
Part Type    Parameters  Vendor    Part #        Cost Qty Total    M-400      Assy   Manufacturer
Electrolytic 4700µF 100V Newark   95F4473      $11.05  2  $22.1   C30-C31      P/S   United Chemi-Con
Electrolytic  700µF  35V Digi-Key 493-1881-ND   $1.51  6  $9.06   C20-C25      P/S   Nichicon
Electrolytic   10µF  35V Digi-Key 493-1850-ND   $0.23  3  $0.69  C1,C5,C16     P/S   Nichicon
Electrolytic  1µF    50V Digi-Key 493-1886-ND   $0.23  4  $0.92 C6,C8,C10,C3   P/S   Nichicon
Electrolytic  22µF   16V Digi-Key 493-1769-ND   $0.15 10  $1.51   C7,C9,C14    P/S   Nichicon
Electrolytic  22µF   16V Digi-Key 493-1769-ND   $0.15            C10-C11 L/R L/R Amp Nichicon
Electrolytic 4.7µF   25V Digi-Key 493-1808-ND   $0.23  2  $0.46    C6 L/R    L/R Amp Nichicon
Electrolytic 470µF  6.3V Digi-Key 493-3014-ND   $1.15  2  $2.30    C3 L/R    L/R Amp Nichicon
Rectifiers      8A  400V Digi-Key GBU8G-BPMS-ND $1.60  3  $4.80  BR2,BR3,BR4   P/S   Micro Commercial
Fuse Holder              Digi-Key 283-2347-ND   $3.45  1  $3.45              Chassis Cooper/Bussmann


You need to "offset" one of the rectifiers so it doesn't short one ot the output transistors, but you'll see that when you're in there.
It should sound like it isn't there!
There is a difference between hearing and listening...
Making life enjoyable through expensive electronics.
_________________
Carver: C-4000 & C-1 preamps, PSC-60 preamp/tuner, TX-11a tuner, M-400 (2), C-500, M-500, M-500t, M-500t Mk.II, A-500x, AL-III loudspeakers (2 pr.)
Sunfire:Theater Grand III processor, Ultimate Receiver, Cinema Grand Signature 400 ~ seven, True Subwoofer Mk. II, D-10 Subwoofer
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tpsretard

Newbie

Posts: 18

Joined: Mon Jan 19, 2009 10:12 am

Post Wed Jan 21, 2009 4:50 pm

Re: M400t Repaire and upgrade

o wow, hay thanks man, u jast saved me some serious work there...
what about the output transistors, did you use anything more 21st century or did u leave the stock ones alone.

I have an accurate schematic for the 400t but i cant seem to get a board layout, my boards are quit different to the lay outs i am seeing with the part numbers on them. the amps do not have the inductor coils on the outputs and a lot of components are oriented different..
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TNRabbit

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(pair of) SILVER-7 TUBE AMPs

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Post Wed Jan 21, 2009 5:06 pm

Re: M400t Repaire and upgrade

There were three different versions: M-400, M-400a, M-400t.
TNRabbit
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tpsretard

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Posts: 18

Joined: Mon Jan 19, 2009 10:12 am

Post Wed Jan 21, 2009 5:23 pm

Re: M400t Repaire and upgrade

from what i can tell the m400 and m400a used the same output boards with the m400a having a better power supply that tracked the =ve and -ve rail together making the amp more stable.

the 400t was a total redesign.
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BillD

User avatar

(pair of) SILVER-7 TUBE AMPs

Posts: 7295

Joined: Wed Jun 06, 2007 8:29 pm

Location: The west's most mid-western town, Scottsdale, Arizona

Post Wed Jan 21, 2009 5:36 pm

Re: M400t Repaire and upgrade

Use MJ15024 and MJ15025 pair to replace all 12 devices
It should sound like it isn't there!
There is a difference between hearing and listening...
Making life enjoyable through expensive electronics.
_________________
Carver: C-4000 & C-1 preamps, PSC-60 preamp/tuner, TX-11a tuner, M-400 (2), C-500, M-500, M-500t, M-500t Mk.II, A-500x, AL-III loudspeakers (2 pr.)
Sunfire:Theater Grand III processor, Ultimate Receiver, Cinema Grand Signature 400 ~ seven, True Subwoofer Mk. II, D-10 Subwoofer

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