I am back again with the same amplifier, my lovely Xtant X604.
Last time I was able to recover the functionality with your help (water leak). Now I discovered that my front left tweeter is not working and making strange sound (I am bi-amping the front end). So I popped the cover off, inspected for water leaks - didn't find any but found 2 burned resistors. One is R111, the other one has no reference designator but since it sits between R108 and R110 it is likely R109. Also did a search before making this post and found the schematic for X603 posted by Perry Barin. Wonder if Perry or someone else has the same schematic without additional markings written over it. Perry was wonderful helping me fix the amp last time I had a short due to water leak that formed crater in pcb (2021). Will try to dig into this tomorrow.
Last time I was able to recover the functionality with your help (water leak). Now I discovered that my front left tweeter is not working and making strange sound (I am bi-amping the front end). So I popped the cover off, inspected for water leaks - didn't find any but found 2 burned resistors. One is R111, the other one has no reference designator but since it sits between R108 and R110 it is likely R109. Also did a search before making this post and found the schematic for X603 posted by Perry Barin. Wonder if Perry or someone else has the same schematic without additional markings written over it. Perry was wonderful helping me fix the amp last time I had a short due to water leak that formed crater in pcb (2021). Will try to dig into this tomorrow.
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Thank you Perry. I replaced 2 100 Ohm resistors. Turned on the head uint and then both of them popped like fuses. Will replace them again and start poking around with dmm. Thankfully the second channel with similar layout is operational.
Are +50 and -50 rail voltages? I see rail +, rail - as well.
Are +50 and -50 rail voltages? I see rail +, rail - as well.
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Assuming the schematic is correct blown R109/11 mean the output is at +rail voltage. Is this the case? Also, I take it +/-rail is something like 40 V?
Apart fromt the resistors I expect many blown transistors, at least the three around the burned resistors. Maybe Q63 too. I'd suggest the lazy method of amplifier repair to disconnect the MOSFETs and return the feedback resistor R44 to either end of R36. Whichever is most convenient. Once you have a stable amp reconnect the MOSFETs.
Apart fromt the resistors I expect many blown transistors, at least the three around the burned resistors. Maybe Q63 too. I'd suggest the lazy method of amplifier repair to disconnect the MOSFETs and return the feedback resistor R44 to either end of R36. Whichever is most convenient. Once you have a stable amp reconnect the MOSFETs.
Perry, the schematic seems to match X604 from what I could tell (quick glance).
I poke around with DMM today. Q51 has emitter-collector short. Once I removed the Q51 the base-emitter short on Q52 was gone and transistors Q53, Q52, Q39, Q63 ohm out the same as on working channel. Schottky diode D67, D65 and D66 appear to be good as well. Same goes for R106, R107.
Need help to identify what Q51 is. It has 3b5 on the packaging. It is likely RCA 256808 (BC856B) will do the job per this thread.
Regenpak, X604 power supply appears to be identical to X604. Attached is the picture showing the rail voltages Perry shared in another thread (X603). I am not seeing a short on the output (Ohmed out amp outputs between positive and negative rails). Though I did discover difference in impedance between R110 and positive reail. On the bad channel I measure 1.03kOhm and the good channel 5.9MOhm. The problem went away when I removed Q65 that was also shorted. Looks like the same part as Q51.
I am open to any suggestions what else to check. Will continue poking around.
PS: I don't have a power supply at home to be able to fire this bad boy the only option is to wire it up in the trunk of my car or go and work in the office. Also don't have twizzer type soldering iron at home but do have the hot air.
I poke around with DMM today. Q51 has emitter-collector short. Once I removed the Q51 the base-emitter short on Q52 was gone and transistors Q53, Q52, Q39, Q63 ohm out the same as on working channel. Schottky diode D67, D65 and D66 appear to be good as well. Same goes for R106, R107.
Need help to identify what Q51 is. It has 3b5 on the packaging. It is likely RCA 256808 (BC856B) will do the job per this thread.
Regenpak, X604 power supply appears to be identical to X604. Attached is the picture showing the rail voltages Perry shared in another thread (X603). I am not seeing a short on the output (Ohmed out amp outputs between positive and negative rails). Though I did discover difference in impedance between R110 and positive reail. On the bad channel I measure 1.03kOhm and the good channel 5.9MOhm. The problem went away when I removed Q65 that was also shorted. Looks like the same part as Q51.
I am open to any suggestions what else to check. Will continue poking around.
PS: I don't have a power supply at home to be able to fire this bad boy the only option is to wire it up in the trunk of my car or go and work in the office. Also don't have twizzer type soldering iron at home but do have the hot air.
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The BC856B is likely right if it's marked 3B.
You don't need a special soldering iron to remove SMD parts. Add new solder to all terminals (resistors and transistors), heat one side and quickly move the iron to the other side and push the component off of the board.
If you use a battery, remember that you need to fuse it with a 10-15 amp fuse to help protect the amp.
You don't need a special soldering iron to remove SMD parts. Add new solder to all terminals (resistors and transistors), heat one side and quickly move the iron to the other side and push the component off of the board.
If you use a battery, remember that you need to fuse it with a 10-15 amp fuse to help protect the amp.
Thank you Perry. I have MMBT4403LT1G at home which is 2T PNP transistor in SOT-23 package. Wonder if I could use them (spare parts I bought for Bash SVS sub amp). I have no idea what ratings are necessary for this application...
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I did notice that BC856B are -65V for Vce and the one I have is only -40V that's why I was asking. Thank you for your help. Will need to place the order for parts so can try these transistors just for fun. I do need to install a switch so I can control the remote amp ON. The head unit doesn't have ability to turn off, once ignition is turned ON it is always stays ON. I have never seen such horrible design. Alpine ILX-650.
I wanted to update you guys on the status. The issue in my case were 2 failed transistors Q65 and Q51 (3B marking) and 2 resistors R109 and R111 (100 Ohm). By mistake I have ordered resistors in SC-70-3 package from mouser (part #863-BC856BWT1G). I did manage to solder them and the amp is up and running. Thank you guys for your support.
I just wanted to follow up. The correct part number for Q65 and Q51 is
Mouser #:
863-BC856BLT1G Mfr. #:
BC856BLT1G
I reworked my unit on the weekend. Apparently had some really loud pops coming from one of the channels likely due to moisture build up. It rains non-stop and the amp is covered but moisture is definitely a serious issue this time of the year.
Mouser #:
863-BC856BLT1G Mfr. #:
BC856BLT1G
I reworked my unit on the weekend. Apparently had some really loud pops coming from one of the channels likely due to moisture build up. It rains non-stop and the amp is covered but moisture is definitely a serious issue this time of the year.
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I am back again. Had another failure on Xtant X604. It plays but the audio but it is distorting (haven't checked the DC offset yet) so I wanted to take a look inside and here is what I have found.
Left rear channel
R817= 100 Ohm blown (eq R109? R122 second amp)
R811= 100 Ohm blown (eq R146)
R819 = 100 Ohm blown (eq R111)
Q811= (Q51 equivalent) shorted
Q809 shorted
Replaced Q811, R817, R811, R819 and still had a short between base and emitter on Q809. Removed the Q809 BR 422 and it is a shorted transistor. BF 422 are obsolete parts. Any recommendations as to what I should use instead? Searching online I have seen someone suggesting using MPSA42 are a replacement but the pinout is different.
BF 422: E-C-B
MPSA42: E-B-C
I may have 3904 available, but it is lower voltage than BF 422.
PS: while ohming out the stuff, discovered R146 was measuring 120 Ohms instead of 100 Ohms from the previous failure. Replaced it with 100 Ohm resistor. The old one was likely cooked during previous failure. This is a note for myself in case I ever have to go back and check.
Left rear channel
R817= 100 Ohm blown (eq R109? R122 second amp)
R811= 100 Ohm blown (eq R146)
R819 = 100 Ohm blown (eq R111)
Q811= (Q51 equivalent) shorted
Q809 shorted
Replaced Q811, R817, R811, R819 and still had a short between base and emitter on Q809. Removed the Q809 BR 422 and it is a shorted transistor. BF 422 are obsolete parts. Any recommendations as to what I should use instead? Searching online I have seen someone suggesting using MPSA42 are a replacement but the pinout is different.
BF 422: E-C-B
MPSA42: E-B-C
I may have 3904 available, but it is lower voltage than BF 422.
PS: while ohming out the stuff, discovered R146 was measuring 120 Ohms instead of 100 Ohms from the previous failure. Replaced it with 100 Ohm resistor. The old one was likely cooked during previous failure. This is a note for myself in case I ever have to go back and check.
The amp is back up and running. Ended up sourcing transistors on ebay (US seller). The offset is drifting on this amp. I wonder if changing rpots could solve this problem (unlikely).
The offset will drift on a change of temperature. Let it idle and stabilize on temperature then blow on the board near the drivers for the channel and it will drift.
Perry, temperature changes in the trunk of my car so much throughout the year. I don't know how long it will take to get to thermal equilibrium in the cold weather. I set the offset with no load/source connected. Then set it again with source and load attached.