Add update to solution

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Ariejan de Vroom 2017-10-15 23:07:49 +02:00
parent 5ed266cd51
commit ca82a81b8d
Signed by: ariejan
GPG Key ID: AD739154F713697B
6 changed files with 22 additions and 10 deletions

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@ -147,18 +147,26 @@ With that, I've narrowed the problem down to `Q808`, a `DHCT-C3` darlington tran
## Repair ## Repair
As with almost every project, diagnosign the issue is much harder and time consuming than the As with almost every project, diagnosing the issue is much more time consuming than the
actual repair. The process is quite simple: actual repair. I ordered a _new old stock_ pair of transistors, this is a set of complimentary
`-A3` and `-C3` transitors including two insulating washers.
1. Order a new pair DHCT-A3/C3 (they are sold in pairs) ![](/img/denon-avr2520-new-transistors.jpg)
2. Replace both `Q808` and `Q809` with the new pair
Done. Next it's a simple job to remove the old darlington transistors...
While I wait for the replacement parts to arrive, I figured I'd start using the amp already. ![](/img/denon-avr4520-new-and-old.jpg)
I have a 2.1 setup, bi-amping the front speakers. Luckily, the AVR allows me to select which
channel (Surround Back or Front Height) to use for this. I disconnected the `SBR` and `SBL` and place the new ones.
amp board as I won't be using them and circumventing the DC power protection problem.
![](/img/denon-avr4520-new-transistors-soldered.jpg)
Finally re-insert the amp board into the amp with some fresh heatsink compound.
**Do not
forget to add the insulating washers to prevent them from shorting out via the heatsink!**
![](/img/denon-avr4520-final-solution.jpg)
## Conclusion ## Conclusion
@ -166,7 +174,11 @@ Replacing the DHCT-A3/C3 darlington transistor pair has resolved the power prote
issues. I've been running the amp in my living room for a few days now and not seen any issues. I've been running the amp in my living room for a few days now and not seen any
issue at all. issue at all.
So, for the cost of a used entry-level AV receiver and € 20 in parts I've got ![](/img/denon-avr4520-final-setup.jpg)
So, for the cost of a used entry-level AV receiver and about €15 in parts I've got
an almost brand new Denon AVR-4520 top-of-the-line AV Receiver. :-) an almost brand new Denon AVR-4520 top-of-the-line AV Receiver. :-)
_For those interested, I'm using the `SBR/SBL` channels to bi-amp my speakers._
[hifiengine]: https://www.hifiengine.com/manual_library/denon/avr-4520.shtml [hifiengine]: https://www.hifiengine.com/manual_library/denon/avr-4520.shtml

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