Hello,
I am new but this looks like a great forum, very informative.
I have a Kenwood head unit KDC-MP825. the other day I had it on and it suddenly stopped sending any signal to the speakers. It still appears to work fine (CD's play, HD Radio tunes, ETC) and I still get signal to the sub from the pre-amp out so this makes me think the internal amp is toast. All fuses (that I can find) check out, and after having opened the unit nothing appears to be overloaded, burnt, loose etc.
I was told the problem is probably in the amp IC. I see 2 main IC's on the board, and in between them I see 2 terminals labeled TEST which I figure is where I need to start but I want some professional advice before I go poking around with my DMM.
I was quoted ~100.00 to have it repaired but I figure with some guidance I can get it sorted out. I found a website with IC's for this unit for about 12.00 each. I have plenty of electrical background and some electronics.
Thanks for any help and guidance you can offer.
Pics: http://www.robbrenner.com/kenwood.htm give it a minute to load, I uploaded them to my site in full-res.
Rob
I am new but this looks like a great forum, very informative.
I have a Kenwood head unit KDC-MP825. the other day I had it on and it suddenly stopped sending any signal to the speakers. It still appears to work fine (CD's play, HD Radio tunes, ETC) and I still get signal to the sub from the pre-amp out so this makes me think the internal amp is toast. All fuses (that I can find) check out, and after having opened the unit nothing appears to be overloaded, burnt, loose etc.
I was told the problem is probably in the amp IC. I see 2 main IC's on the board, and in between them I see 2 terminals labeled TEST which I figure is where I need to start but I want some professional advice before I go poking around with my DMM.
I was quoted ~100.00 to have it repaired but I figure with some guidance I can get it sorted out. I found a website with IC's for this unit for about 12.00 each. I have plenty of electrical background and some electronics.
Thanks for any help and guidance you can offer.
Pics: http://www.robbrenner.com/kenwood.htm give it a minute to load, I uploaded them to my site in full-res.
Rob
The internal amplifier is going to be mounted to the heatsink and will have ~25 pins.
Have you tried disconnecting all of the speaker wires from the head unit and using a test speaker to check the amplifier's output? If a speaker wire shorted to the chassis ground somewhere, the amplifier may have shut down to protect itself.
Have you tried disconnecting all of the speaker wires from the head unit and using a test speaker to check the amplifier's output? If a speaker wire shorted to the chassis ground somewhere, the amplifier may have shut down to protect itself.
It appears that the IC has failed.
If you decide to replace it, you need to be careful when removing the old IC from the board. I'd suggest using a razor knife or a pair of fine tipped cutters to cut the leads at the body of the IC. If you use a razor knife, you'd make several passes on the legs where they enter the body of the audio amplifier IC.
After separating the body from the leads, you can remove the leads individually. Apply new solder to the connection and then pull the lead (very gently) while heating the solder joint. Then clean the holes with a desoldering tool or desoldering braid (but not the stuff from radio shack).
Apply heatsink compound to the IC before replacing the heatsink.
If you decide to replace it, you need to be careful when removing the old IC from the board. I'd suggest using a razor knife or a pair of fine tipped cutters to cut the leads at the body of the IC. If you use a razor knife, you'd make several passes on the legs where they enter the body of the audio amplifier IC.
After separating the body from the leads, you can remove the leads individually. Apply new solder to the connection and then pull the lead (very gently) while heating the solder joint. Then clean the holes with a desoldering tool or desoldering braid (but not the stuff from radio shack).
Apply heatsink compound to the IC before replacing the heatsink.
To make sure I am looking at the right IC (sorry for my newbi-ness) it looks like it is IC4, on the back of the unit (was clamped to the heat-sink) and is marked as;
ST
TDA7560
H22CR0417
MALTA
0.4
And has 25 pins as mentioned above. If thats the case, any advice on where to find a replacement?
I found:
PartStore.com which lists that part as
analog IC 2019v ($34.29)
But on KenwoodParts.com its listed as
TDA7560 Power IC ($34.29)
OR
E-TDA7560A Power IC ($30.26)
Neither of which have the KDC-MP825 listed under models they fit.
Thanks for your continued help.
Rob
ST
TDA7560
H22CR0417
MALTA
0.4
And has 25 pins as mentioned above. If thats the case, any advice on where to find a replacement?
I found:
PartStore.com which lists that part as
analog IC 2019v ($34.29)
But on KenwoodParts.com its listed as
TDA7560 Power IC ($34.29)
OR
E-TDA7560A Power IC ($30.26)
Neither of which have the KDC-MP825 listed under models they fit.
Thanks for your continued help.
Rob
Looks like it's available at the usual distributors. Both DigiKey and Mouser carry it and have it currently in stock for about $22. It seems that this IC is available only in the one package, so if that's how the dead one is marked, the replacement should fit. Since this part seems to be easy to get, I wouldn't recommend using one of the 'part search' type vendors. They tend to jack up prices and aren't as reputable.
Are you absolutely sure it is not a grounded or shorted speaker problem? Most oem decks don't have short/ground protection and will keep playing even if one of the speakers or speaker wires is having issues. Aftermarket decks are getting better though, and most have protection and some even tell you which speaker is the culprit on the screen.
Also check pacific coast parts distributors, they have kenwood parts for good prices
Also check pacific coast parts distributors, they have kenwood parts for good prices
Kenwood are a good brand of radio but I have seen reports and have had it happen to me with my last receiver. The internal amplifiers tend to die out for some reason..?? It's the reason I had to get a new radio 2 years ago..My old Kenwood had the same thing happen...No highs but I had lows. It burnt out on me. Be careful with the MP series as well...I have experiences now with it overheating with my MP4028. If you play it very loud for a long period of time, the highs will fade down and then back up again and the only way to stop it is to turn it down and let it cool down. I've seen reports on Yahoo all over the net about people with the same issue. I hate to say it but my next HU more than likely will not be another Kenwood (Unless maybe a Excelon in which someone had said he had no issues after changing from his MP series). Other than that, I might look into a Alpine or Pioneer....Dern internal amplifiers 
Perry:
I went ahead and ordered the IC from MCM, I'll pick it up in the morning since they're about 15 minutes down the road from me. I also ordered some other stuff I need for my tool bag.
ppia600:
If one of the speakers were having a short to ground, wouldn't it cause a sound quality problem with the OEM HU installed? I will check and meter everything before I put the Kenwood back in.
Flyin11:
I too had this unit cranked up pretty loud for about 45 minutes before the problem occurred (neighborhood block Halloween party). It wasn't outputting any signal to the component speakers, the only thing that was receiving signal was the external amp which powered my sub. I am looking to upgrade to the Excelon KDC-X891 if this doesn't fix the MP (or even if it does possibly). I want to stay with Kenwood since I already have the HD tuner, trying to avoid buying a new HD unit too.
The replacement IC cost $16.00 so 'll hopefully get time to swap it in tomorrow afternoon and see if it works. Even if it doesn't, its some much needed soldering practice
I went ahead and ordered the IC from MCM, I'll pick it up in the morning since they're about 15 minutes down the road from me. I also ordered some other stuff I need for my tool bag.
ppia600:
If one of the speakers were having a short to ground, wouldn't it cause a sound quality problem with the OEM HU installed? I will check and meter everything before I put the Kenwood back in.
Flyin11:
I too had this unit cranked up pretty loud for about 45 minutes before the problem occurred (neighborhood block Halloween party). It wasn't outputting any signal to the component speakers, the only thing that was receiving signal was the external amp which powered my sub. I am looking to upgrade to the Excelon KDC-X891 if this doesn't fix the MP (or even if it does possibly). I want to stay with Kenwood since I already have the HD tuner, trying to avoid buying a new HD unit too.
The replacement IC cost $16.00 so 'll hopefully get time to swap it in tomorrow afternoon and see if it works. Even if it doesn't, its some much needed soldering practice
If you don't have a good desoldering tool:
http://www.mcminone.com/product.asp?product_id=21-4699&catalog_name=MCMProducts
http://www.mcminone.com/product.asp?product_id=21-4699&catalog_name=MCMProducts
"ppia600:
If one of the speakers were having a short to ground, wouldn't it cause a sound quality problem with the OEM HU installed? I will check and meter everything before I put the Kenwood back in."
Many of the oem units don't even stop playing. Some will make distortion but some just ignore the problem channel. I've had customers buy decks wanting to install themselves and come back saying "the deck wont play" the speakers but the oem one did. After realizing they could have had a free labor install by us, we adjust the ticket and install it only to find one or more speakers is grounding out. We can usually sell the pair that has the problem speaker or at least totally disconnect the problem speaker channel if they don't want to replace the speaker.
Its worth a try to check the speaker wires of the car to ground at the harness and also the resistance of each lead. If that isn't the problem, you definately will be having some soldering fun.
If one of the speakers were having a short to ground, wouldn't it cause a sound quality problem with the OEM HU installed? I will check and meter everything before I put the Kenwood back in."
Many of the oem units don't even stop playing. Some will make distortion but some just ignore the problem channel. I've had customers buy decks wanting to install themselves and come back saying "the deck wont play" the speakers but the oem one did. After realizing they could have had a free labor install by us, we adjust the ticket and install it only to find one or more speakers is grounding out. We can usually sell the pair that has the problem speaker or at least totally disconnect the problem speaker channel if they don't want to replace the speaker.
Its worth a try to check the speaker wires of the car to ground at the harness and also the resistance of each lead. If that isn't the problem, you definately will be having some soldering fun.
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