onkyo ht-r290 - My Next Project

[madan1]

Re: onkyo ht-r290 - My Next Project

Those amps are not repair-friendly.. when speaking about disassembly.
A good start will be to remove the back plate.. lot's of bolts there.
Then you will have to remove all boards which are above the bottom board ( where the power amps/ICs are ) and finally - the power amp board from the chases ( most likely you will have to remove it with the heatsink ).
And keep in mind that the backplate is used for ground connection between the boards, so there is a very good chance the unit not to want to start at all without it.

[SolomonMan]

Re: onkyo ht-r290 - My Next Project

madan1,
Thanks for the reply!
I was curious how I was going to test this thing (power-wise) unless I set it on my test bench in pieces and re-connect. (Looks like that will be the solution!)

Once I got pass those white power connectors it seems very possible...now!

I was hoping it was going to be a slam dunk on the Amplifier IC replacement...I am guessing it still could be...?

Thanks
Chris

[madan1]

Re: onkyo ht-r290 - My Next Project

Hi Chris, if I remember correctly the design of those units, the power slash I/O board is the one between the power amp ( the bottom one ) and the HDMI board ( the top/green one ). If you are lucky enough, you will not have a vertical board connecting all that boards.
Anyway, I just wanted to say that for testing purposes you can substitute the backplate ground with croc connectors. Still, everything has to be arranged on the chases.. unless you have the service extender cables.

[SolomonMan]

Re: onkyo ht-r290 - My Next Project

Hi Chris, if I remember correctly the design of those units, the power slash I/O board is the one between the power amp ( the bottom one ) and the HDMI board ( the top/green one ). If you are lucky enough, you will not have a vertical board connecting all that boards.
Anyway, I just wanted to say that for testing purposes you can substitute the backplate ground with croc connectors. Still, everything has to be arranged on the chases.. unless you have the service extender cables.

madan1/all ,
This brings up a question in my mind on how to troubleshoot things.

I still believe that the IC Amplifier(s) are probably the culprits. Which one and getting to the point of testing them may be the real challenge/work of this project.

As we are going to be tearing things down to get to that point;

If any of these "sub" boards (i.e. HDMI board) were to blame would disconnecting them and testing (powering on) help troubleshoot where the problem may lie quicker?

Meaning if the unit does not power on but disconnecting the HDMI board then allows it to power on and stay on. The HDMI circuitry is probably a good place to start looking kind of idea.

As you mentioned earlier ground may be another thing altogether.

There are a few boards in this unit. There is a vertical board on the far right but its fairly small and it appears to connect by a push in connector type setup (2 connections). It looks easy to remove but this unit has defiantly a "tower" setup to it.

If I could remove/eliminate good board from bad it would (I believe) make things easier to troubleshoot.

I guess I am missing the "order" of events that are occurring in this amplifier to make it happy.

I would assume something must be sending (or not) a signal to power down (relay).

tibimakai mentioned the resistors close to the rear relays. The resistors do not appear to be film resistors (carbon/metal - color coded as I expected). They are smaller but not SMD. I wonder if somehow they are involved in the power off.

Thoughts?

Again Thanks for the help,
Chris

[madan1]

Re: onkyo ht-r290 - My Next Project

No. You can't just remove boards and expect the unit to power up.
In brief - the hdmi board is the brain and the unit will not even try to start without it.
The middle board contains part of the power supply for the hdmi board ( if I remember correctly )
And then you have the bottom board which contains the power amp. Yamaha likes to put there the vol control IC, but can't remember if onkyo does the same with that entry level AVRs... anyway, probably you can boot the unit without that board, but will not help you a lot.
Almost forgot the display board, which I think can also be removed.

By the way, have you checked the service manual for this unit? This is the first thing you should do. As I mentioned above - there is a service menu in which you can see the recorded protection errors that prevented the unit from starting. This will save you at least some amount of head scratching.

And if you haven't figured it out yet - when you have two identical ICs ( as in your case ) just probe them and compare the readings with those of the other IC. And why don't you get the ICs datasheet? They will show you the pinout and will make the search for short way easier. Usually the short will be between V+, V- and output.
Keep in mind that the speaker output goes through a relay to the speaker terminal... which reminds me that you can try testing for voltage on the speaker terminals ( or even better - on the IC output pin ). If you get anything more than a volt - you have a problem.

[SolomonMan]

Re: onkyo ht-r290 - My Next Project

No. You can't just remove boards and expect the unit to power up.
In brief - the hdmi board is the brain and the unit will not even try to start without it.
The middle board contains part of the power supply for the hdmi board ( if I remember correctly )
And then you have the bottom board which contains the power amp. Yamaha likes to put there the vol control IC, but can't remember if onkyo does the same with that entry level AVRs... anyway, probably you can boot the unit without that board, but will not help you a lot.
Almost forgot the display board, which I think can also be removed.

By the way, have you checked the service manual for this unit? This is the first thing you should do. As I mentioned above - there is a service menu in which you can see the recorded protection errors that prevented the unit from starting. This will save you at least some amount of head scratching.

And if you haven't figured it out yet - when you have two identical ICs ( as in your case ) just probe them and compare the readings with those of the other IC. And why don't you get the ICs datasheet? They will show you the pinout and will make the search for short way easier. Usually the short will be between V+, V- and output.
Keep in mind that the speaker output goes through a relay to the speaker terminal... which reminds me that you can try testing for voltage on the speaker terminals ( or even better - on the IC output pin ). If you get anything more than a volt - you have a problem.

madan1,
Thanks for the information!

I will try and get some time to troubleshoot it this weekend again.

I do have to play with a furnace on Saturday (all new burners) but if that goes well I should have time to "play".

I will see if I can locate that IC datasheet.

I did have a Service Manual (General) for the unit but it was not exactly the greatest and I included it in this thread.

Again thanks for the help,
Chris

[SolomonMan]

Re: onkyo ht-r290 - My Next Project

All,
I have located the below datasheet (put it on my google drive);

https://drive.google.com/file/d/14G_...ew?usp=sharing

The two I have are STK443-530.

In the PDF image it appears to have 15 pins (Package Dimensions). On my unit there are 18 pins (Image Below)?

I will check for Voltages at the speaker terminals. Output pins appear to 5 and 11 and I will check output there as well not to mention the other IC pins.

Thanks
Chris

[SolomonMan]

Re: onkyo ht-r290 - My Next Project

Guys,
I located a better Service Manual (My Google Drive);

https://drive.google.com/file/d/15Iy...ew?usp=sharing

Thanks
Chris

[madan1]

Re: onkyo ht-r290 - My Next Project

Page 7 has a nice pinout of the STKs.

pins 1 2 3 - V+ V- gnd
8 9 additional low voltage power supply for the pre-amp section
10 11 13 14 15 16 - audio signal inputs
4 5 6 7 17 18 power amp outputs
See the pair of resistors.. those which are close to the coils.. like r6164 and r6174.. you will find them on every output. Usually if a channel blows, those resistors also go.
So try testing them first. They are 0.22ohms so you might have problems measuring them but they are nice, big components which are easy to access with the probes.




by the way, just read again the thread from the beginning and watched the video.. well this does not look like a protection error to me.. especially the part where the display is cycling between on and off.
Every unit that I have had with a gone channel never did that. It has always been power on, then after a second or two straight to power off... never such cycling.
This looks like a smps/IC trying to start or rebooting.. which reminds me that onkyo also has a history of bad smd caps on the hdmi boards, but usually this happens to the more complicated amps where there is almost no air flow between the boards.

[tibimakai]

Re: onkyo ht-r290 - My Next Project

He is turning it on every time.

[madan1]

Re: onkyo ht-r290 - My Next Project

He is turning it on every time.

You are totally right, sir! I guess I was too sleepy/drunk when watched the video .
Anyway, almost always when I have been working on blown channels, the units were popping fuses if there is no current limiter or the burnt transistors are not disconnected from the power rails.. but I guess integral amps work differently.

[SolomonMan]

Re: onkyo ht-r290 - My Next Project

He is turning it on every time.

That is correct! I am turning it on every time.

Thanks
Chris

[SolomonMan]

Re: onkyo ht-r290 - My Next Project

All,
Thanks for the help,

Got the furnace all set.

Now to something fun.

There appears to be NO shorts between ground and 4 5 6 7 17 18 power amp outputs.

The 6 sets of resistors like r6164/r6174 all measure at .4 ohms which I believe is correct (resistors in series .22 + .22 = .44).

The Voltage readings at the IC are a little bit of a different story;

I have included a pic of what I am doing for testing;

Basically the black lead Alligator Clip to the Chasis.

The Red lead to IC pin using a IC clip.

Voltages are as follows (when I push power on and before it clicks off);

Left IC

Pin4 - .25 V
Pin5 - 1.5V
Pin6 - 5V
Pin7 - .25V
Pin17 - 2.31V
Pin18 - 5.3V

Right IC

Pin4 - 3.75 V
Pin5 - .25V
Pin6 - .25V
Pin7 - 6.25V
Pin17 - 24.75
Pin18 - 25.00V

The Right IC pins 17 and 18 are pushing 25Volts on the Right IC. I tested this 3 times and each time 25 Volts.

Another thing that is interesting is when the relay (the click) flips off (assumed). The voltage on some of the other higher leads may switch polarity (+-) with a significant voltage changes down but still usually over 3 Volts and the voltage then stays consistent and then slowly bleeds away.

I am going to have to review the schematics etc...Any ideas?

Thanks again everyone for the help,
Chris

[madan1]

Re: onkyo ht-r290 - My Next Project

...Right IC

Pin4 - 3.75 V
Pin5 - .25V
Pin6 - .25V
Pin7 - 6.25V
Pin17 - 24.75
Pin18 - 25.00V
...

There it is.. now cut pins 1 and 2 and try to power the unit.
By the way what is the voltage on pins 1 and 2?

[SolomonMan]

Re: onkyo ht-r290 - My Next Project

mandan1,
pins 1 and 2 on both ICs are 24.95 volts.

Cutting pins 1 and 2 on the right side allowed the amp to stay on and put out music on half the channels.

I assume just replacing the STK443-530N will correct the problem?

Thanks
Chris

[madan1]

Re: onkyo ht-r290 - My Next Project

Are you sure about the polarity of the voltage? One should be positive, the other one - negative.
Also, according to the service manual - the power supply should be +/- 49. Check the user manual and be sure that 8ohm speakers are selected and check again that rails.

When you have power rail voltage on the output, this usually means that a transistor has shorted. In your case I would also check the input signal for that particular channel ( pins 15 16 ), just to be sure that there is not something wrong on the pre-amp.


And yes, if the pre-amp is fine, installing a working STK should fix the problem.

By the way, why don't you try to connect back pins 1 and 2 and cut the output pins for the bad channel ( 17 18 ). I have never worked on such ICs and wonder if it is possible only a single channel to fail or a failure like that will affect all channels/IC.

[SolomonMan]

Re: onkyo ht-r290 - My Next Project

Are you sure about the polarity of the voltage? One should be positive, the other one - negative.
Also, according to the service manual - the power supply should be +/- 49. Check the user manual and be sure that 8ohm speakers are selected and check again that rails.

When you have power rail voltage on the output, this usually means that a transistor has shorted. In your case I would also check the input signal for that particular channel ( pins 15 16 ), just to be sure that there is not something wrong on the pre-amp.


And yes, if the pre-amp is fine, installing a working STK should fix the problem.

By the way, why don't you try to connect back pins 1 and 2 and cut the output pins for the bad channel ( 17 18 ). I have never worked on such ICs and wonder if it is possible only a single channel to fail or a failure like that will affect all channels/IC.

madan1,
1) I remeasured the voltage on pins 1 & 2. Both the Left and Right IC (Right IC pins 1 & 2 were cut) and I measured the bottoms remaining pins. They measued both ~49.8 Volts and the polarity was switched between pins 1 & 2.

2) On the cut IC (Right IC pins 1&2) pins 15 & 16 measured .04 Volts and .01 Volts.

3) When I connected the Right IC pins 1 & 2 again the Amp shut down like it did before I cut pins 1 & 2. I then proceeded to cut pins 17 & 18 (pins 1 & 2 connected) and tried things again (Power on). The amplifier was still protecting itself and it shut down even though pins 17 & 18 were cut. If I removed pins 1 & 2 again on the Right IC as expected the system would power on. So it appears that IC is the problem.

On the replacement I have a couple options and I want some opinions;

Ebay - Used - Guaranteed working;
https://www.ebay.com/itm/STK443-530-...oAAOSw59JfrBuK

Ebay - New
https://www.ebay.com/itm/NEW-1PCS-ST...C/283852126283

Its not a financial thing one is going to be here considerably faster than the other.

First question are both of these the same as mine?

Pin number seems correct on both and the new appears to be a Sanyo brand.

Second question is there any problem mixing the brands?

Third question can I use thermal silver CPU heat paste on this IC?

Again Thanks everyone for the help!
Chris

[madan1]

Re: onkyo ht-r290 - My Next Project

Well, I hoped that if you cut the faulty channel pins, you could use the rest, but no luck here. Looks like the fault has affected and the other channels which puts the amp into protect mode.

I can't give you an advice about a replacement.. but I have read that there are many fake STK ( https://www.youtube.com/watch?v=EZJjqpDaSZs ).
Probably look for good seller feedback or search the threads here for more info. I guess I would get a used original one.

Yes, you can use thermal paste as long as it does not short any pins to each other or to the heatsink.

[SolomonMan]

Re: onkyo ht-r290 - My Next Project

madan1,
Thanks for the help!

I will probably pick up the used one in the hopes of getting it fixed over my Christmas break.

I will let everyone know the outcome of the fix!

Thanks again!
Chris

[tibimakai]

Re: onkyo ht-r290 - My Next Project

https://www.digikey.com/en/products/...30N-E/11551447
Select the First class USPS, for cheaper shipping.