Alpine MRV-1507 - RCA Ground Floated - Need help

[Perry Babin]

Were the RCA shields connected to chassis ground when you were measuring the voltage on the amp?

The Z48v will work in place of the N version.

The power supply FETs will have no effect on the regulated voltage.

You stated earlier that you had 12v on pin 14 of IC703. Unless I followed the wrong circuit. It appears that Q604 (8v reg) supplies voltage to pin 14 of IC703. Is this not correct (confirm with ohm meter)?

[silversweden]

I had them grounded when measuring the 2nd ground
indication circuit..when checking the regulated voltage i didnt
had them grounded-

I can confirm that IC703 pin 14 is directly connected to Q604
wich has excatly 8 volts out....

Have to measure the voltage on IC702 again...strange
last time i measured i had 12volts with a small pulse.


About the +-15volt reg circuit...its taking voltage directly
after the rectifyer and feeding into the regulator circuit(15volts)

And IC702 (the battery indicator IC)
takes the supply voltage from this +-15Reg..
And its not giving me +-15Volts :S

Measured it to +17,5 and -13,3 wich in my eyes isnt good.


I am going to take a sleep now :P just find more and more to dig in, and its not good to fault finding several things simultanius =)

[Perry Babin]

Measure the regulated voltage again but this time, place the black meter lead on the RCA shield of the amp.

[silversweden]

after replacing some pow-fets i measured the
regulated voltage with black lead on rca ground.

Perfekt!


takes a week for my local shop to get me another DTA144EK

and if i order from digikey.com ord mouser they take 50$!!!!
in shipping flat rate... no way... whatg should i do

is it possible to just take a transistor from my junk boxes
and bias it with two 47k resistors as the DTA144 is biased?

or is it just a stupid idea :S

Cant measure the voltages untill i have the componet in
circuit i guess :S

[silversweden]

IC702
1 -13.6
2 5.3
3 6
4 -15
5 0.28
6 14,3
7 14,3
8 14,9

SHOULD BE
(15,5)
(4,67)
(7,1)
(-15,8)
(1,8)
(1,5mV)
(1,8)
(15,9)


IC703
1 0-10v pulsing
2 0.2
3 0.3
4 0-10v pulsing
5 0-10v pulsing
6 9.4p
7 0.3
8 11.5
9 0.28
10 0-10v pulsing
11 0.3
12 0.3
13 0-10v pulsing
14 0.3

SHOULD BE
pin1 1
pin2 7.4
pin3 1
pin4 1.7mV
pin5 1
pin6 15.5mV
pin7 1.6mV
pin8 11mV
pin9 1.7mV
pin10 1.7mV
pin11 1.8mV
pin12 1
pin13 1.6mV
pin14 8V
Very strange readings, what the hell??? have all ICs gone wacked? :S

The 8 volt supply is ok ive checked it!
and the +-15 volt reg is OK... what is happening here

[silversweden]

Now i discovered that 8volt Reg is NOT OK!!!

With RCA ground connected to chassi ground
11.66V
11.5V
12.4V

Without RCA ground.
6.46V
9.4V
7.0V

What is going on :S not strange that the ICs have 14,5 volts
with a small pulsing on them...

[Perry Babin]

You have to be careful of the reference you use. If you leave the RCA shield grounded, you can use either the chassis ground or the shield as the reference. I'd suggest that you connect the shield to the chassis ground for all future measurements.


What is the voltage across ZD601 (black lead on anode)?

What is the voltage from the anode of ZD601 (black lead) to the emitter of Q604?

Is the voltage between the anode of ZD601 and chassis ground 0v.

[silversweden]

You have to be careful of the reference you use. If you leave the RCA shield grounded, you can use either the chassis ground or the shield as the reference. I'd suggest that you connect the shield to the chassis ground for all future measurements.

---Ok then i will !


What is the voltage across ZD601 (black lead on anode)?

---Voltage across ZD601 = 8.75V

What is the voltage from the anode of ZD601 (black lead) to the emitter of Q604?

---Voltage from anode ZD601 to emitter (leg 1...) of Q604 = 8.12
(someone have resolderd this before, donnow why...)


Is the voltage between the anode of ZD601 and chassis ground 0v.

---Voltage from anode ZD601 ---->>> chassie with black lead on RCA ground (still with chassie ground tiead to RCA shields = 0.82

Isnt that strange ? =)

[Perry Babin]

The regulator components appear to be OK. There may be a bad solder joint between the chassis ground and the anode of ZD601. Desolder and resolder all of the connections on Q604 and D601. If you still read nearly 0.9v, you need to determine why. There shouldn't be more than 0.1v. Ideally, there would be a 0.0v difference. The 0.82 difference probably isn't a real problem but it could indicate that there's a bad connection somewhere which could cause intermittent problems. I'm assuming that you still read 0v between the RCA and chassis grounds.

[silversweden]

Hello Perry!
Now i have replaced ALL caps on the power supply board!

And i cleaned the "soldering" side gentle with some topz
and flux off as good as i could between components
and around the ICs.

Did the same thing on the "component" side. Was a lot of
"dust" on the board around the cooling fan and dust had
stuck between components (just a layer of dust...)

Not like dust balls :P whatever...


Now i have a reading of 0.002V if i place a lead on the Zener
and to ground (still with RCA ground connected to chassi)



Strange thing is that IC701 pin4 (is connected After ic 703)
here i have exactly 8Volts!!! Rock steady...


On IC703 pin 14 i still got around 11 volts with a small pulsing
around 10,8 and 11 volts..... the same frequensy as the LEDs flashing.


A very strange thing is if i place one lead on pin 4 of IC701
and the second on IC703 i get some wierd ohm reading.


Can i say from this that IC703 is leaking internally?


There would be nice if i could remove it without destroying the IC.

6 legs on each side :S Any tips of how to remove it with a ordinary
soldering iron? I have two of them if needed, even 3 :P
But not 6 of them!! :P

If i could remove it then i could measure pin 14 without the IC
in place to see if i have 8Volts....