Hifonics BRUTUS BX1500D Problem

[mika111]

New caps ordered..I took Panasonic TS-HA series this time, should be as good as Rubycons in my opinion

HD -series to that 12VDC side and TS-HA to secondary 63V side.

 

[mika111]

New caps installed....no effect -> power led is still red

 

[Perry Babin]

Is this with the 4080 out of the circuit?

 

[mika111]

Is this with the 4080 out of the circuit?

No..4080 out of circuit power led is green.

4080 in the ciruit, power led is red.

Speaker relay clicks in both situations.

Amp FETs show a bit weird resistances between G-S, there are 4 banks of 3 FETs and one bank measures ~250kOhm, two measures ~130kOhm and the last measures ~1,2MOhm..

http://kuvaton.com/k/Y5Di.jpg

 

[Perry Babin]

Measure the resistance from the gate of each bank to the corresponding output pin on the 4080. Do you read ~100 ohms for each?

 

[mika111]

Yes..76ohms in each one of them.......

 

[Perry Babin]

Check the diodes that are connected in parallel with the gate resistors. You'll need to pull either 1 leg of the resistor or 1 leg of the diode.

Confirm that they conduct in only 1 direction.

 

[mika111]

I replaced those diodes on gates and pulldown..also replaced resistors with them but it's still measurin weird. Banks on the other side measure 458kOhms bank1 and 615kOhm bank2 and it stays there. Other side bank3 457kOhms stays and bank4 start with 200kOhms slowly rising to OL if I change probes other way it starts from 0ohm and slowly rises to OL. WTF is happening are the bank4 fets gone? They're new..all measures between G-S and no 4080 installed.

 

[mika111]

I pulled out those bank4 fets and they all measure OL with every probe combination....measured from board bank4 places, it does the same than with fets on -> resistance slowly rises to OL

 

[mika111]

Also took out of the circuit inductor and resistor going to IC -> nothing changed

Picture:
http://kuvaton.com/k/Y5dy.jpg

 

[mika111]

I took all the amp fets out of board..still the same issue

 

[Perry Babin]

You don't have to post it here but you should make a list of the voltage on all pins of the 4080, IC1C and IC2C. Compare the voltages on all pins. Which are different with the 4080 in the circuit and with it out of the circuit?

 

[mika111]

Ok..I´ll do that tomorrow. I am just wondering that now there is no place on board that could do that.
I have fets out, 4080 out, inductor out and that resistor out..it doesn´t fit in my brains that how the h....l measuring resistance can do that still

 

[Perry Babin]

I can't answer that question. I've never used that method to troubleshoot a fault with this type of amp. Maybe the voltage differences will lead to an answer. If so, you may be able to determine why the resistance readings are different when you know what's causing the fault.