MTX 81001, Want to know the value of two parts

[dinoo]

Hello,

I have an MTX TA81001, at this moment there are two parts defective.

The locations from the parts are Q405 and Q401.

I want to know the part number, the values of these parts and the alternate parts.

Thank you.

 

[Perry Babin]

Q405 is likely marked 6P or C1 which is an MMBFJ111 or SST111 (equivalent parts).

Q401 is marked 1D and is an MMBTA42.

The JFET isn't likely defective. They read about 10 ohms from drain to source out of the circuit.

 

[dinoo]

The Q401 Marked as 1DZ is defective for sure.
The Q405 Marked as C1URA is defective also (The base and emitter contact each other constant).

It broke the two A3120 Chips at location U403 and U402

Thank you for your reply before Perry Babin, are you sure those are the equivalent parts?

 

[Perry Babin]

The C1 transistor is a JFET and will read approximately 10 ohms out of the circuit between drain and source. Look up the datasheet. The two legs that you refer to as base and emitter are drain and source. The top leg is the gate.

 

[dinoo]

Perry Thanks for your fast reply.

The measured results from the C1URA are:
From Drain to Source: 28 Ohm and 27 ohm (going down)
From Drain to Gate: 5,12 Ohm
From Source to Gate 5,12 Ohm



For those who are interested in the full story with pictures.

On my MTX 81001 are the following parts defective:

C406 marked as 35V 1000UF
C408 marked as 35V 1000UF

D404 marked as 1001
D405 marked as ES2D
D406 marked as ES2D

D401 marked as 831B

U402 marked as A3120
U403 marked as A3120

Q401 marked as 1DZ
Q405 marked as C1URA

The Led400 turns onn.
Also the "For Service Only" Led turn onn

 

[dinoo]

The part at location D401 marked as 831B is this a zener diode?
And how much volt is this diode?
What is the equavalent part fort this?

 

[Perry Babin]

http://www.mouser.com/ds/2/308/1SMA5913BT3-D-108672.pdf

 

[dinoo]

Perry Thanks a lot !!!

 

[dinoo]

it seems that location R468 with a SMD Resistor 1000 is defective

and

location D409 Diode J5C.

Does anyone know the equivalent part for location D409 (Diode J5c)?

 

[Perry Babin]

MMSZ5250BT1

 

[dinoo]

Hello,

I replaced the following locations

C406 marked as 35V 1000UF
C408 marked as 35V 1000UF

D405 marked as ES2D
D406 marked as ES2D

D401 marked as 831B

U402 marked as A3120
U403 marked as A3120

Q401 marked as 1DZ
R410 marked as 1001

I recently also replaced Location R468 marked as 1000 and Location D409 marked as J5C.

After replacing these parts i decided to turn onn the amplifier with a 12V 2A adapter.

So i turned onn the amplifier and after 3 seconds i saw some smoke coming up from the area with location numbers C411, D404, R410 and the chip A3120.

Does someone know why the smoke is coming.

 

[Perry Babin]

Precisely what component was smoking?

 

[dinoo]

The A3120 above location C411 was smoking i think.

Also the Zener diode on location D404 marked as J5C is broken

 

[Perry Babin]

D404 is the voltage reference for the opto-coupler's voltage regulator. It will have to be replaced before you can do anything else.

Also check FET401 (near the RCAs). is it shorted?

 

[dinoo]

Oke, i will replace the d404 first.

Yes the FET401 is shorted
What is the equivalent part for this FET.

It is the left FET as you can see on the picture.


Do i need to check anyting else?

 

[Perry Babin]

Use the original part. If it failed, the opto-coupler connected to it has likely failed also.

 

[dinoo]

Oke im ging to replace the Opto copler.

The Fet401 marked as IRF540 is this a N Chanell Fet?
The D404 is this a J5C ? (mine is broken cant read the number)

 

[Perry Babin]

J5 is the marking for the part number. That converts to MMSZ5250B. Contact MTX if you want confirmation.

Until you get the regulators working properly, I'd suggest pulling the two 3120s and soldering a jumper connecting pins 5, 6 and 7 on each 3120. This will prevent damage to the opto-couplers and the jumpers will keep the outputs from switching on.

Yes. Look up the datasheet for the IRF540.

 

[dinoo]

Thanks, i will wait till the parts arrive.

At the location R407 i`m measuring 1.10 ohm and going up.

Is this resistor good?

 

[Perry Babin]

IF the shorted FET is still in the circuit, you will have to remove it or the resistor to check it.