sony strdh 720 This is a topic that many people are looking for. militaria-agent.com is a channel providing useful information about learning, life, digital marketing and online courses …. it will help you have an overview and solid multi-faceted knowledge . Today, militaria-agent.com would like to introduce to you SONY STR-DH720 Home Theater Receiver. Following along are instructions in the video below:
“Welcome back everybody and welcome. My first official repair video now in my new workshop. Workshop. It s getting set up i ve got receivers.
There s some stuff i to still work on i need a table over here the subject of my other video. The network board is running strong got my computer set up so anyway. This video was kind of unexpected. I had not expected to be repairing a black plastic home stereo receiver and it was kind of dropped on me by accident more or less so here s what happened about two and a half three years ago.
I was at costco and i was looking for a receiver that would do surround sound for my home theater setup. And i m running across a model that was actually this model. Although not this exact receiver. It s a sony.
Str d. H. 720. And before what happened was i was living in a much smaller apartment and i didn t really have the space to have you know 71.
Channels and all that kind of stuff and i had another black plastic home stereo receiver that would do surround sound. But it was a little bit less capable so i ended up giving this one or this model that i had to my father for use in their new home stereo surround setup. Which it is currently still serving its purpose quite well and now that we ve moved here. I needed another receiver and the thing.
I really loved about this receiver. When i had mine was that it was incredibly easy to use it has upscaling from any source. So you can use the component. The composite s video just about anything it handled 3d.
Although i don t plan on using that functionality. It s nice to know that it s there at least 4 hdmi inputs. The other ones don t support 3d. Obviously but overall just a really nice receiver and the other cool thing about it was if you hook it up to an hdmi on your display.
You actually get gui to set up with the remote all the different features. So you don t have to try and you know scroll through these buttons or whatever on the front panel. The front panel shows minimal information. And i think you can do most of the setup.
If you wanted through the front panel. But i didn t i liked the nice little gui on the screen of my tv. Which was wonderful..
But i started to miss that receiver and i started looking around for a receiver. That was the same or comparable today and i probably sure could have spent about 500. But i really liked this unit. When i had one and so i went ahead and bought one off ebay that was listed in the listing as working fully working or working.
Normally as what they said all i get it home. And i turn it on and all it says on the display is protect and i m not getting the click of the speaker relay well we all know from vintage stuff that protection can be a bunch of different things. But in this case. I contact i did not want a project nor did i want a project.
I still spend a decent amount of money on it was better than new one but wasn t still you know it still cost a decent amount of money so i contacted the seller. And he basically had me try a few things i ended up calling sony s tech support line their help was useful enough. But nothing out of the ordinary mainly trying the receiver without any inputs or outputs getting to it just the power to see if it was caused by something either at the input of the output. Which did not turn out to be the case it still was doing it even with just the power cord connected so i asked the seller.
What do you want to do next. And he issued me a refund and never wanted the receiver back. Which is fine. I don t know he s going to do with it.
But i figured i would open it up and see if i could see anything to try and fix. It so here it is on the bench. Let s take a look inside. And see what we can find well here.
It is open on the bench. And the thing that strikes me immediately is that there s really not much to this receiver. The heaviest component by far is the power transformer and that s still not that heavy this thing weighs in a total of about 10 pounds. Although the quality does not seem to be lacking in any euler area.
This heatsink is fairly sturdy. It s got a fairly thick plate to it i ve removed an hdmi board and a small power supply board from this connector here. So i could get to the output section. Which i believe to be this there are seven channels.
Plus. The point one is a non powered sub out. It s just the line level sub out. That s why they re calling at the point.
One. And you ve got an emitter recessed through a dual emitter resistor and a pair of transistors for each channel. It appears..
I don t know which one is which i d have to get the schematic. But i think my first order of business is going to be to start testing transistors here in the output section. There s really not much to it it looks like you ve got a dual driver or preamp type driver ic for each channel here there s four of them which means actually one channel of one of them would not be used or it s driving the sub out. Which is actually probably more likely.
The case and then you ve got your pair of output transistors emitter resistor couple supporting components. Some eighth watt through hole resistors. Which are pretty rare and you got two very unbe fiy. So flat caps filter caps.
These kind of look like the shrinking is happened on the sides on the label. But it appears that s not the case based on the way these are designed does not actually appear to be shrinking. It s just it s just the way the caps are assembled so i m gonna actually start testing these output transistors. I did notice when i was trying this receiver out a couple of times.
I would get a very faint burning smell while i was testing it out from the inside so there s something but i don t see any burnt components on here. So i ll try that and see if we can see anything that s out of the ordinary well we found something here that shouldn t be as it is tested all the transistors across this row in circuit with the diode test results. Maybe a little bit of ronis in one direction or the other but they matched on all channels. Except those two they re where i ve drawn the black x across it with a sharpie and those two across all pins on those things read zero zero zero on a diode test resistance.
Everything is low or just a complete short. Which should explain to me why the protection circuit. Was stuck on because you don t want to turn on speaker outputs that thing going on so i ve done. Some research and i found out that these transistors aren t super easy to get i can get a pair of them that is actually legitimate they re not fake or counterfeit.
So i m gonna have to order those looks like it ll be about 10 bucks for the pair which considering. I was refunded for the defective receiver may be a worthwhile investment to see if i can get this thing running so i m gonna go ahead and order those well. It s thursday and my transistors showed up probably a little bit earlier than i was expecting because i ordered them a couple of days ago. I got a men 2048 and an mn 1620.
There they also included some heatsink grease. Which is nice i have some but i took the receiver apart here you can see there s the front and then the back and the main board kind of come out together it seemed like the best way to take it apart. And i was a little bit dismayed when i turned over the circuit board. And saw a ton of surface mount components.
Here and obviously i do not have the tools to deal with surface mount stuff at all so i m sincerely hoping that all the surface mount parts are okay and just the main transistors that are bad. But i still can test my meter can still test these things so hopefully you can kinda see around each output section. There s a grouping of components right here right here here. I think it s this one that s bad.
I just flip. It over and make sure you know you can see the groups of components. So that s kind of neat..
But there s only one way to find out i guess. And that is to actually take it out and so we ve got going well. I ve discovered another issue and that is that the emitter resistor. This is the dual emitter resistor for that channel.
There s actually two resistors inside this. Casing both connect to the center pin 02. 2. Ohms.
5. Watt and one side of it is bad. I believe. It s this right side.
So i had to put the project on hold for a few days. And i ve ward in some new mid resistors they came in a pack of 10. I work on other audio equipment. So and this is a common value so i ll sure i ll use them at some point.
But i ve got this one out and i have yet i ve decided the transistors. But i haven t actually taken them off the board or mounted them off the heatsink yet so i m going to have to do that put those in put. The emitter sister in and then we ll see what s going on well. I ve got the receiver pretty much back together.
None of the screws are in but the way it stands on the posts. I should be okay to power it up got the new transistors in there you can see the new resistor down. There right there so let s give it a shot plug it in alright well. I heard that click and buy now would have gone into protection.
I have nothing up after obviously i like this little source select now that s kind of nice reminds me the older stereos. I like chef you know the function select this goes through everything if i recall correctly you can actually name these yourself. Because i remember i think with the with the receiver. I had i named one phone.
Oh and then i had a funnel preamp hooked to one of the auxiliary inputs or something like that and i think you can name but i think you have to use the hdmi function. I m gonna finish putting all the screws back in it because right now the things are kind of just laying on each other and then i ll actually get up to some speakers and see if we get some sound out of it well. I ve got the receiver hooked up now to some speakers and plugged in. I ve also got hooked up to this tv.
So this is bd dvd. Now let s think cannot focus on the tv apparently. I ve got this computer hooked up there i wanted to demonstrate well let s place him let s play some music..
I actually still had something up there. What i will send to earlier. Oh here s something turn that down son get it muted. But i want to demonstrate one other cool thing.
The receiver seems to be working just fine. I wanted to demonstrate the men the on screen menus so there i ve got my computer showing you could have your dvd player or whatever and hit the menu button here and it actually changes to and on of course they can t focus. But it changes to an on screen display there you can actually change a bunch of settings in a receiver there s you can set up tuning calibration speaker setup surround equalizer audio dual mono you can do a bunch of cool stuff in this menu and hdmi settings. That s really cool i must ve accidentally hit something that lets me get into the ah that s interesting turn it off.
I might have hit. I had a accidentally hit about three buttons on the remote. Oh. Maybe.
That s the tv sanyo something yes. Yes the tv doing hanna like i might accidentally hit something on the tv room. But i haven t try to need the upscaling features of the receiver. Yet you know some of the tv actually not on the receiver.
Good. There it is well that s sound on the tv. Let s meet that for sam you can do is really neat you go in the menu here and from this point out. It s just going to be talking about the receiver.
The repair video is finished. There is a function here and i want to say it s in this audio. Thing now it s not in the other thing. It s jim.
I maybe hear you say tv. Oh you can t even read that there tv plus amp. That means. It will send the audio signal to the tv as well as playing it out the amplifier.
If i change it to just amp. You can barely see there am. Then it will not play out the tv. Even if there s sound you know even if i miss up on the tv.
It will not play so that s pretty neat. But there it is receiver and ” ..
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