MTX thunder elite 1501d

Hexhclass

Member
2010-06-22 6:08 pm
usa
The traces for the speaker terminal burnt,not sure what cause the shot.The resistance across the speaker terminal was about 20 ohms.I had to cut the burn part of the board away to get 2.3k across them. Outputs test fine in circuit.I see 6v across the speaker terminal and the LED for service is on.Any suggestions on this one?
 

Hexhclass

Member
2010-06-22 6:08 pm
usa
The negative regulated circuit not working,I see about 47v on pin four of the op-amp closest to the RCA jack.The resistors that smoke is connect to pin four and eight of that same op-amp.I disconnect the pre-amp board at the moment to prevent damage if it has not yet been damage.

What parts make up the negative reg voltage?
 

Perry Babin

Member
Paid Member
2003-11-20 11:01 am
Louisiana
www.bcae1.com
In the photos I have, R138 and 139 are power supply gate resistors. Is your amp different?

If the negative regulator is driving 50v to the op-amps, virtually every op-amp on the main board has likely been damaged. On the preamp board, many of the 10 ohm resistors feeding the power supply pins of the op-amps have likely opened.

If you have the full tutorial, look at the MTX7801 page. It shows the regulator circuit.
 
They getting so hot i can see them starting to sink in the core.Also i can smell them.
If the inductor ares ok what order fault could cause them to over heat?
Both heat up same temperature.

I just notice there is 7v offset just before LED 400 comes on.After it it on the voltage goes down to 0.00 instantly.