Hi Brannigan,
Questions. What transistors did you replace? Did you check any others and how?
-Chris
Questions. What transistors did you replace? Did you check any others and how?
-Chris
Chris,
I checked all the transistors mounted on the big heatsink and then I replaced Q101SL (2SD389) and Q103SL (2SB1559).
I used a DMM to measure resistance between the different transistor legs. The broken transistors had close to 0 ohms resistance between two legs.
I checked all the transistors mounted on the big heatsink and then I replaced Q101SL (2SD389) and Q103SL (2SB1559).
I used a DMM to measure resistance between the different transistor legs. The broken transistors had close to 0 ohms resistance between two legs.
Hi Brannigan,
I would recommend you replace the drivers as well. Possibly the bias transistor also. Did you check the emitter resistors, as well as the resistor between the bases?
Once you have done that, adjust the control to make the voltage across the emitter resistors the same as the other channel. Recheck every 15 min for an hour. I don't have the manual, so I can't advise you more than that.
-Chris
I would recommend you replace the drivers as well. Possibly the bias transistor also. Did you check the emitter resistors, as well as the resistor between the bases?
Once you have done that, adjust the control to make the voltage across the emitter resistors the same as the other channel. Recheck every 15 min for an hour. I don't have the manual, so I can't advise you more than that.
-Chris
Chris,
I'm not familiar with amp designs, so basically I've just been poking around with a DMM looking for broken parts. I haven't checked any resistors.
I forgot to mention that the amp is working, but you still recommend I replace the drivers and bias transistor?
I'm not familiar with amp designs, so basically I've just been poking around with a DMM looking for broken parts. I haven't checked any resistors.
I forgot to mention that the amp is working, but you still recommend I replace the drivers and bias transistor?
Hi Brannigan,
I got that feeling, hence my questions.
Normally I check transistors for leakage. I replace one stage back from the last damaged part. Since you can't check for leakage, just change the drivers and bias. We know for sure excessive current went through them. Test diodes and other transistors using your diode check function, there should be a small transistor to sense over current through an emitter resistor, a few resistors between. Check the low value resistors, up to 1K0, for opens. They may look fine and still be open.
That should do it. Light bulb in series when you turn it on the first time. I use a variac and do testing as I increase voltage.
I wish you luck.
-Chris
I got that feeling, hence my questions.
Normally I check transistors for leakage. I replace one stage back from the last damaged part. Since you can't check for leakage, just change the drivers and bias. We know for sure excessive current went through them. Test diodes and other transistors using your diode check function, there should be a small transistor to sense over current through an emitter resistor, a few resistors between. Check the low value resistors, up to 1K0, for opens. They may look fine and still be open.
That should do it. Light bulb in series when you turn it on the first time. I use a variac and do testing as I increase voltage.
I wish you luck.
-Chris
Chris,
Thanks for you help 🙂
I've checked all diodes and most resistors. Some resistors are very low values, so I'll check the voltage across those once I've put the amp back together.
Do you have any suggestions for where I can find 2SD947 transistors? I've only found these at MCM, but they have a $250 minimum on international orders.
I've put together an approximate schematic of the output stage.
Thanks for you help 🙂
I've checked all diodes and most resistors. Some resistors are very low values, so I'll check the voltage across those once I've put the amp back together.
Do you have any suggestions for where I can find 2SD947 transistors? I've only found these at MCM, but they have a $250 minimum on international orders.
I've put together an approximate schematic of the output stage.
Attachments
Hi Brannigan,
Is there a distributor for Denon in your country? Why not just order the spares from there? Check how much a manual is, it may not be that expensive.
If the parts come from Denon, they will not be fakes. The really low value resistors are probably the emitter resistors. You measure across these to determine bias current.
-Chris
Is there a distributor for Denon in your country? Why not just order the spares from there? Check how much a manual is, it may not be that expensive.
If the parts come from Denon, they will not be fakes. The really low value resistors are probably the emitter resistors. You measure across these to determine bias current.
-Chris
Yes, there's a distributor. I've emailed them about a service manual (I have the user manual), but I never got a reply. I'll give them a call tomorrow.
Good, I think that would make your life a lot easier. You might find a good friendly tech there to give you a hand if needed. We will here as well, that goes without saying.
-Chris
-Chris
2SD947
Hi,
you can get them for 1 Euro each at www.nedis.com, but you have to be a dealer or so. I f you want I can get some for you and send them to you.
I also have a Denon AVR-1602sm.pdf
greetings Michael😀
Hi,
you can get them for 1 Euro each at www.nedis.com, but you have to be a dealer or so. I f you want I can get some for you and send them to you.
I also have a Denon AVR-1602sm.pdf
greetings Michael😀
Hi Michael,
Would you mind sending me a copy of the PDF? That would be very kind of you. bhome at sympatico dot ca
Thank you
-Chris
Would you mind sending me a copy of the PDF? That would be very kind of you. bhome at sympatico dot ca
Thank you
-Chris
I called the distributor today and they quoted me ~$35 for two 2SD947 and two 2SC1845. Delivery time 3-5 weeks. 🙁
Michael,
Looks like I need your help if it's not too much trouble. I'll send you a PM.
Michael,
Looks like I need your help if it's not too much trouble. I'll send you a PM.
Hi Micheal,
Boy, that was expensive. And on top of that, they didn't even have them in stock ?? How do they fix them I wonder.
-Chris
Boy, that was expensive. And on top of that, they didn't even have them in stock ?? How do they fix them I wonder.
-Chris
The distributor doesn't repair anything. It's handled by local repair shops. My friend got a quote for repairs from one of these and it was $300. The repair shop said they had to replace the transformer, but I can't see anything wrong with it. (Maybe they missed the broken fuse.)
Denon needs a new distributor. The repair estimate is well in excess of what I have seen, the incompetence borders on illegal.
-Chris
-Chris
AVR-1602 schematic
Here you'll find the Schem:
http://fileshare.eshop.bg/downloadsm/19719/Denon_AVR-1602.html;)
Here you'll find the Schem:
http://fileshare.eshop.bg/downloadsm/19719/Denon_AVR-1602.html;)
So, I need a 2SC947F (not 2SD947) and a KSC1845. KSC1845 is available from Mouser, but I haven't found a source for 2SC947F except for the Denon distributor. Any suggestions for where to look for hard-to-find transistors?
Michael,
Thanks for the schematics. They've been very helpfull.
Michael,
Thanks for the schematics. They've been very helpfull.
anatech said:
I measured across the emitter resistors connected to the test points:
Front, left: 3.28 mV
Front, right: 4.61 mV
Center: 3.14 mV
Surround, left: 2.97 mV
Surround, right: 7.42 mV
The transistors I replaced were in the left surround channel.
I assume these values differ too much?
Hi Brannigan,
The bias on the right surround channel is too high. The left is fine. The other values are acceptable as they range in the same ballpark. I haven't read the service manual, so the right surround bias might be within tolerance.
Does it work?
-Chris
The bias on the right surround channel is too high. The left is fine. The other values are acceptable as they range in the same ballpark. I haven't read the service manual, so the right surround bias might be within tolerance.
Does it work?
-Chris
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