Are you using diode continuity or ohms range on your meter ?
Use Ohms range please, diode range is limited to 100 to 200 ohms usually, so its not a wide enough range IMO.
Any 2.1 and 1.2 reading indicate shorted conditions ( as measured from the center lead as common). I recommend you pull only the center pins and read out to either side with the pulled pin as a common for both readings. Please retest this way and any 1.2 or 2.1 reading just go ahead and finish pulling the fet leads out of circuit.
Don't worry about red or black to which pin. A dead short will read either way without any consideration for polarity.
Those fets cost less then a Big Mac Meal deal total and you should replace all to be safe. I believe your looking at IRF9540 and IRF540 3 each for 6 total.
There are better fets available now that will drop in circuit nicely and give you balanced current load capacity.
Once you have found the bad fets, pull all the pins and check the drivers 1358 and 3421 transistors I pointed out when you came by my shop. These usually survive OK but you must check anyway. And also read the big resistors, they should all read the same <center lead is common>
PLEASE don't call me J.O.M.A. thats that e-bay person
Use Ohms range please, diode range is limited to 100 to 200 ohms usually, so its not a wide enough range IMO.
Any 2.1 and 1.2 reading indicate shorted conditions ( as measured from the center lead as common). I recommend you pull only the center pins and read out to either side with the pulled pin as a common for both readings. Please retest this way and any 1.2 or 2.1 reading just go ahead and finish pulling the fet leads out of circuit.
Don't worry about red or black to which pin. A dead short will read either way without any consideration for polarity.
Those fets cost less then a Big Mac Meal deal total and you should replace all to be safe. I believe your looking at IRF9540 and IRF540 3 each for 6 total.
There are better fets available now that will drop in circuit nicely and give you balanced current load capacity.
Once you have found the bad fets, pull all the pins and check the drivers 1358 and 3421 transistors I pointed out when you came by my shop. These usually survive OK but you must check anyway. And also read the big resistors, they should all read the same <center lead is common>
PLEASE don't call me J.O.M.A. thats that e-bay person
i believe that i am using the ohm. there is a "M" and then the "ohm" symbol. it is a fluke 23 meter i can press the button and it will move the decimal place to the left. and then switch to "k"
ALL 4 of the big white resistors read with 0.6 both sides
so you want me to resolder pins 1 and 3 back to the board and pull pin 2 and retest?
once i find the bad one this way then test the little buggars in the "driver" seat!!
do i pull the other side aswell to get a good comparison?
im up for an upgrade on this guy.
I appologise for the shortening of the name... ill let that be.
so with that.......... JUSTONEMOREAMP thanks so much for your help!
ALL 4 of the big white resistors read with 0.6 both sides
so you want me to resolder pins 1 and 3 back to the board and pull pin 2 and retest?
once i find the bad one this way then test the little buggars in the "driver" seat!!
do i pull the other side aswell to get a good comparison?
im up for an upgrade on this guy.
I appologise for the shortening of the name... ill let that be.
so with that.......... JUSTONEMOREAMP thanks so much for your help!
Don't forget the outputs on the vertical boards.
With the FETs out of the board, you have to check them in the proper order and with the proper lead connections or you may get erroneous readings. When the FET is out of the circuit, the gate can be charged by the voltage produced by the meter. With the gate charged, the FET will conduct and may seem to be leaking or shorted. The readings depend on the threshold voltage of the FET and the voltage the meter produces across its leads when on diode test or resistance. Generally, the voltage is less on resistance (2.0v vs 2.6 v for most fluke meters) so you may get fewer erroneous readings than on diode test but it's still not 100% reliable.
On the 23, the diode test setting is 1 click clockwise from the resistance setting.
Unless you follow the proper order, the only thing you can rely on to determine whether the FET is defective is leakage/continuity between the gate and either of the other leads. The gate of a good FET (of this type) will always be 100% isolated from the other pins.
With the FETs out of the board, you have to check them in the proper order and with the proper lead connections or you may get erroneous readings. When the FET is out of the circuit, the gate can be charged by the voltage produced by the meter. With the gate charged, the FET will conduct and may seem to be leaking or shorted. The readings depend on the threshold voltage of the FET and the voltage the meter produces across its leads when on diode test or resistance. Generally, the voltage is less on resistance (2.0v vs 2.6 v for most fluke meters) so you may get fewer erroneous readings than on diode test but it's still not 100% reliable.
On the 23, the diode test setting is 1 click clockwise from the resistance setting.
Unless you follow the proper order, the only thing you can rely on to determine whether the FET is defective is leakage/continuity between the gate and either of the other leads. The gate of a good FET (of this type) will always be 100% isolated from the other pins.
MRV-1505 Need some help
I have the full service manual with schematic here:
www.itxpress.se/mrv.pdf
Justonemoreamp: You sad something about running
a ground wire to the RCA shield. But where should
i look on the schematic to figure out the bad ground?
Need some help
I have the full service manual with schematic here:
www.itxpress.se/mrv.pdf
Justonemoreamp: You sad something about running
a ground wire to the RCA shield. But where should
i look on the schematic to figure out the bad ground?
Need some help
Re: MRV-1505 Need some help
Silversweden, do you have any others that you would like to share?
silversweden said:I have the full service manual with schematic here:
www.itxpress.se/mrv.pdf
Justonemoreamp: You sad something about running
a ground wire to the RCA shield. But where should
i look on the schematic to figure out the bad ground?
Need some help
Silversweden, do you have any others that you would like to share?
Re: MRV-1505 Need some help
Good evening Silversweden,
This sort of failure is extremely common place on this series of Alpine amps. It tells me the tech that the amp has been severely abused by it owner.
The symptom is a faulty ground circuit for the RCA shield ground to the ground of the + & - 16 volt lower rail supply. I have found a small inductor open and I have found circuit board traces flashed depending on how far the amp was pushed into hard clipping and how long.
The simple test for this issue is to clip a jumper on the RCA shield barrel and the find the common ground point located back at the 16 volt regulators, and attach the ground for these two supplies to that RCA shield.
The proper results will be a properly operating amp, that comes out of start up diagnostics and starts to play music, instead of flashing the on LED on and off.
You have the diagram, start tracking this common ground for the + & - 16 volts. I start right at the regulators and head forward to the amp board. I usually find a blue and black inductor is the culprit. Its usually opened by the excessive current flow that occurred through it < pops like fuse every time>
The inductor is called out in the schematic clearly and Alpine has it listed in the BOM parts list. < if my memory is working correctly tonight>
To be honest a piece of wire as a jumper seems to cause no degradation to the amps performance, and the wire does not fail. In fact if the owner continues his abuse the next failure will be a simple circuit board trace that will flash like a fuse. The trace will be located on the bottom of the board in one of two spots. one is located on the amp board, and the other is on the power supply board. Both traces will be located on the bottom of the board so the amp will have to come completely apart again either way.
Generally at this point because this is so common place any warranty the owner paid for is out the window..
I hope you find this helpful, I have only done like a couple hundred of these over the years since they originally came out
silversweden said:I have the full service manual with schematic here:
www.itxpress.se/mrv.pdf
Justonemoreamp: You sad something about running
a ground wire to the RCA shield. But where should
i look on the schematic to figure out the bad ground?
Need some help
Good evening Silversweden,
This sort of failure is extremely common place on this series of Alpine amps. It tells me the tech that the amp has been severely abused by it owner.
The symptom is a faulty ground circuit for the RCA shield ground to the ground of the + & - 16 volt lower rail supply. I have found a small inductor open and I have found circuit board traces flashed depending on how far the amp was pushed into hard clipping and how long.
The simple test for this issue is to clip a jumper on the RCA shield barrel and the find the common ground point located back at the 16 volt regulators, and attach the ground for these two supplies to that RCA shield.
The proper results will be a properly operating amp, that comes out of start up diagnostics and starts to play music, instead of flashing the on LED on and off.
You have the diagram, start tracking this common ground for the + & - 16 volts. I start right at the regulators and head forward to the amp board. I usually find a blue and black inductor is the culprit. Its usually opened by the excessive current flow that occurred through it < pops like fuse every time>
The inductor is called out in the schematic clearly and Alpine has it listed in the BOM parts list. < if my memory is working correctly tonight>
To be honest a piece of wire as a jumper seems to cause no degradation to the amps performance, and the wire does not fail. In fact if the owner continues his abuse the next failure will be a simple circuit board trace that will flash like a fuse. The trace will be located on the bottom of the board in one of two spots. one is located on the amp board, and the other is on the power supply board. Both traces will be located on the bottom of the board so the amp will have to come completely apart again either way.
Generally at this point because this is so common place any warranty the owner paid for is out the window..
I hope you find this helpful, I have only done like a couple hundred of these over the years since they originally came out
Hi again
I find that very helpfull!
When i bought the amp i knew that it was not working propertly.
The first times when i tested the amp it powerd up smooth.
But then I figured out that i had to jumper the Remote and +12v
before I actually connected the +12v from battery. If i turned it of by disconnecting the Remote cable and then connected it again it would not start.
Schematic: www.itxpress.se/mrv.pdf
Then i found out that zenerdiod "ZD503" in the bottom right corner of the schematic near IC503-504 was shorted. 0 ohms both ways( yes i disconnected one legg and measured it
I have replaced it with a new zenerdiod 9.1v.
But now the amp dont work without the ground wire from RCA shield to Ground terminal. Seems like something has broken and i cant figure out why. Cant understand why ZD503 is broken since no "big" currents are flowing there. And when i connect that ground wire from RCA it powers upp but the leds first powers up then down and then upp again. Just like some capacitor stop the current after 1 sec so that the current to ground have to take another way and then it powers upp again.
And the amp getts very hot around the DC-DC drive circuit (dont know if its the rectifyers) and then it powers down after 5-10 minutes. Dont know if its because i dont have the amp screwed to the chassi or if something is wrong there to. A lot of things are strange!
Do you have any tips on that? Would be very helpfull. Really want this amp to function propertly without that extra wire.
Thanks again! youre beutifull /stefan
I find that very helpfull!
When i bought the amp i knew that it was not working propertly.
The first times when i tested the amp it powerd up smooth.
But then I figured out that i had to jumper the Remote and +12v
before I actually connected the +12v from battery. If i turned it of by disconnecting the Remote cable and then connected it again it would not start.
Schematic: www.itxpress.se/mrv.pdf
Then i found out that zenerdiod "ZD503" in the bottom right corner of the schematic near IC503-504 was shorted. 0 ohms both ways( yes i disconnected one legg and measured it
I have replaced it with a new zenerdiod 9.1v.
But now the amp dont work without the ground wire from RCA shield to Ground terminal. Seems like something has broken and i cant figure out why. Cant understand why ZD503 is broken since no "big" currents are flowing there. And when i connect that ground wire from RCA it powers upp but the leds first powers up then down and then upp again. Just like some capacitor stop the current after 1 sec so that the current to ground have to take another way and then it powers upp again.
And the amp getts very hot around the DC-DC drive circuit (dont know if its the rectifyers) and then it powers down after 5-10 minutes. Dont know if its because i dont have the amp screwed to the chassi or if something is wrong there to. A lot of things are strange!
Do you have any tips on that? Would be very helpfull. Really want this amp to function propertly without that extra wire.
Thanks again! youre beutifull
/stefan
Q307-318 all have about 0.5 ohms to ground
And the two IC have also about 0.5 ohms
is it some good way to measure the ground breake.
Measure all ground connections in some way?
And a stupid question now why is it a capacitor
in series with almost every ground connection?
Maybe its a capacitor thats broken?
And a strange thing is when i jumper Remote and
+12v battery and then put power on the battery
terminal it powers up (the two red leds that are placed
on the amp board) but then it powers down after 1 sec
and i have to place a jumper from RCAshield to Ground.
Q320 and Q322
pin 1 3Mohm climbing
pin 2 12kohm climbing
pin 3 12kohm climbing
Q319 and Q321
pin 1 O.L
pin 2 O.L
pin 3 O.L
You can se on the board that
Q109 Q110 Q106
Q209 Q210 Q206
Hast gone hot. its slightly darker around them on the board.
Q110 has ben resolderd some time
Someone help me its a djungle of connections
And the two IC have also about 0.5 ohms
is it some good way to measure the ground breake.
Measure all ground connections in some way?
And a stupid question now
why is it a capacitorin series with almost every ground connection?
Maybe its a capacitor thats broken?
And a strange thing is when i jumper Remote and
+12v battery and then put power on the battery
terminal it powers up (the two red leds that are placed
on the amp board) but then it powers down after 1 sec
and i have to place a jumper from RCAshield to Ground.
Q320 and Q322
pin 1 3Mohm climbing
pin 2 12kohm climbing
pin 3 12kohm climbing
Q319 and Q321
pin 1 O.L
pin 2 O.L
pin 3 O.L
You can se on the board that
Q109 Q110 Q106
Q209 Q210 Q206
Hast gone hot. its slightly darker around them on the board.
Q110 has ben resolderd some time
Someone help me
its a djungle of connectionsThe 0.5 ohm connections confirms that there are no breaks in the ground connection. All of these points should be at 0v when the amp is powered up.
The capacitors 'in series with the ground connections' are bypass capacitors. They shunt higher frequencies to ground. You'll find them in the power supply and audio sections.
I assume that you were measuring the resistance from the pins of Q319-Q322 to chassis ground. If so, this is probably normal. The secondary is isolated and it floats.
There's no easy way to check every ground. You can check the shield ground continuity from the RCA shield (signal cables and jumpers removed) to the center tap of the secondary side of the power transformer. There should be ~0 ohms.
I'm not sure which inductor he was referring to but most inductors in the power supply will read ~0 ohms when you measure the resistance across their terminals. An open inductor would read as infinite resistance.
Will the amplifier power up if you ground the shields? If so, maybe we could get some voltage readings on various points. That would help with troubleshooting.
The capacitors 'in series with the ground connections' are bypass capacitors. They shunt higher frequencies to ground. You'll find them in the power supply and audio sections.
I assume that you were measuring the resistance from the pins of Q319-Q322 to chassis ground. If so, this is probably normal. The secondary is isolated and it floats.
There's no easy way to check every ground. You can check the shield ground continuity from the RCA shield (signal cables and jumpers removed) to the center tap of the secondary side of the power transformer. There should be ~0 ohms.
I'm not sure which inductor he was referring to but most inductors in the power supply will read ~0 ohms when you measure the resistance across their terminals. An open inductor would read as infinite resistance.
Will the amplifier power up if you ground the shields? If so, maybe we could get some voltage readings on various points. That would help with troubleshooting.
Measure the DC voltage on all 3 legs of one each of the IRF540s and IRF9540s from each channel (12 voltage readings total).
Measure the DC voltage on each leg of the regulator transistors (Q319-Q322).
Use the secondary center tap as the reference point (black meter lead on secondary center tap).
0 ohms across the inductor means it's not open. A shorted inductor would read the same but probably wouldn't affect the circuit. Unless the insulation on the inductor looks like it overheated, it's likely OK (as long as it reads near 0 ohms).
Measure the DC voltage on each leg of the regulator transistors (Q319-Q322).
Use the secondary center tap as the reference point (black meter lead on secondary center tap).
0 ohms across the inductor means it's not open. A shorted inductor would read the same but probably wouldn't affect the circuit. Unless the insulation on the inductor looks like it overheated, it's likely OK (as long as it reads near 0 ohms).
Your correct Perry
Have you tried reading from the center tap common point on the power supply < Neg Probe> to the RCA shield <red probe> ?? This should be a 0 ohm reading. If not the Star ground from the amp board that connects to the common ground for both power supplies is open. This is what I have always found on these.
I found bad connectors <I.E. burnt contacts>, Blown traces, and open inductors that caused this issue. If I could point directly to the culprit I would have in my earlier post. Please forgive my inattentiveness, My life has its hectic moments.
I thank you Perry for covering my absents, Please carry on with Silversweden. I know he is in great hands with your guidance.
I measured from TP1 (located on the right corner of schematic page 15 in service manual) www.itxpress.se/mrv.pdf
Is that the center tap common point?
If i measure from RCA shield to TP1 the value starts from 1kohm
and climbing above 11kohm. Is something wrong here?
If i wait about 5 minutes and then connect battery to battery
terminal the amp will power up. But just if i have a wire allready
between Remote and Battery Terminal.
If i remove remote wire and then but it back the amplifyer wont
power up. Then i have to wait about 5 minutes again. Dont know
if you understand what i mean.
Could it just be some faulty capacitor wich is doing this?
Seems strange to me that the amp powers up if i have
the wire connected between Remote and Battery terminal
before i connect the +12V from battery.
I have measured a whole lot thes weekend =) Everything seemes
to be OK on the transistors according to schematic!
I can write it out if that will help you?
Is that the center tap common point?
If i measure from RCA shield to TP1 the value starts from 1kohm
and climbing above 11kohm. Is something wrong here?
If i wait about 5 minutes and then connect battery to battery
terminal the amp will power up. But just if i have a wire allready
between Remote and Battery Terminal.
If i remove remote wire and then but it back the amplifyer wont
power up. Then i have to wait about 5 minutes again. Dont know
if you understand what i mean.
Could it just be some faulty capacitor wich is doing this?
Seems strange to me that the amp powers up if i have
the wire connected between Remote and Battery terminal
before i connect the +12V from battery.
I have measured a whole lot thes weekend =) Everything seemes
to be OK on the transistors according to schematic!
I can write it out if that will help you?
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