onkyo ht-r990

[harleyman58]

has anyone worked on this receiver, is there a way to check the amps on this machine it has only three power amps. pics on the way and schematics.

[Khron]

Re: onkyo ht-r990

Page 7 quite clearly shows the "main features" inside those amplifier chips, that you need to know.

First step would be to check if any of the (internal) output transistors are shorted: +Vcc to ChX+RE and ChX+RE to -Vcc.

[harleyman58]

Re: onkyo ht-r990

yes I saw the chip layout but I don't know anything about audio amp chips, the industrial side of electronics doesn't cover that.
thank you kenny

[harleyman58]

Re: onkyo ht-r990

ok no shorts on any of those pins on any of the three chips. does the hdmi board control the sound of all the receiver? should the radio still play if the hdmi is bad?

[Khron]

Re: onkyo ht-r990

Page 3 is entirely dedicated to the audio block diagram / signal flow diagram.

Does the receiver work, otherwise? Does it power on? Relays clicking, and all that?

I don't suppose you have access to a signal generator or something, do you?

[harleyman58]

Re: onkyo ht-r990

yes the receiver powers on display works, only the first set of relays click on. the second set of relays do not power on ,it goes into protect mode. no I don't have a signal generator, all I have is a good fluke meter the will check diodes and caps, ac,dc volts and mv

[harleyman58]

Re: onkyo ht-r990

if I knew what to buy I would get one. within reason.

[Khron]

Re: onkyo ht-r990

Does it say anything like "protect mode" on the display? Or how do you know? And are the two main supply rails ok? The ones across the two big filter caps, i mean.

On page 7, there's a group of diodes pointing downwards, around the middle of the page. Under them, there's a couple transistors, and the labels on the signals going out from them are "Vprotect" and "Iprotect". With the receiver powered on, it would be interesting to see if / how much DC there is on each output.

I'm guessing it should be simple and/or easy enough to probe each output (obviously, before the relays) in the connector JL600A/B, which carries all the speaker signals. Measure between each output and ground (which isn't necessarily directly connected to the chassis). I see JL603A/B is dedicated to carrying the speaker grounds.

Anything under 50mV or so should be safe. If that's the case, it'll be interesting to find out if the current-protection trips (and how to figure that out).

[harleyman58]

Re: onkyo ht-r990

no it does not say protect on the display, I only have one click powering the main circuit. the board only has q6022 and q6023 on it the other two transistors q6021 and q6024 are not there. also diodes d 6020 through d6026 are not on the board. also on c 6092 there is an arrow pointing to the + side of the cap saying v prot a.nd on c6706 saying v olh

with the exception of q6010 through q6016 those are the only transistors on the board.

[harleyman58]

Re: onkyo ht-r990

on the -15 volt circuit it is acting strange, sometimes the ground leg of the transistor shows ground and sometimes not. also the number 1 leg of the transistor shows ground the same way. I am going to change the -15 volt transistor and check the other components in the circuit. had to order the transistor.
any thoughts kenny

[Khron]

Re: onkyo ht-r990

Are you positive all those components are "not on the board"? Or are they just not where you might've expected them to be? Just because they're right next to each other on the schematic, doesn't mean it's the same story on the board itself.

The +/-15v seem to be coming of of two REGULATORS. Yes, discrete transistors can also be packaged in TO220 cases, but the 78xx / 79xx series are voltage regulators (look up the datasheets).

Have you tried resoldering those legs? Or can you at least provide a photo of that area?

[harleyman58]

Re: onkyo ht-r990

im going to resolder them this morning, yes I know the 78/79 are voltage regulators. I will send pics of the entire board.

[harleyman58]

Re: onkyo ht-r990

ok found all the transistors and diodes they are on the bottom of the board. they are very small.

[harleyman58]

Re: onkyo ht-r990

I don't know what else to check ,relays 691,692,693,694 are pulling in and I have +55 volts and -55 volts coming out of the caps feeding the amps.

[harleyman58]

Re: onkyo ht-r990

ok on page 6 we have the 15 volt regulators. with two caps and two diodes on the out going side. taking a reading at the regulators I have 15 volt + and - .if I take a reading after the diodes I have 29 volts. then following that on to the 7 volt I have 13 volts ,past the two resistors on each leg.

[Khron]

Re: onkyo ht-r990

You have +/-29v(?) after which exact diodes? Or are you measuring between the two outputs of the regulators?

If you've got the black probe on the negative rail and the red one on the positive rail, then it sounds ok (ie. within acceptable tolerances; 15v above ground and 15v below ground add up to 30v between them; 29's close enough - same logic for then +/-7v rails).

[harleyman58]

Re: onkyo ht-r990

yes that is what I did a probe on each rail. I cant find anything wrong tho. I don't know what else to look for.

[harleyman58]

Re: onkyo ht-r990

I cant understand whats not working. the video works, so hdmi good. if the receiver is off the video and sound pass through. no messages on the screen. all voltages seem good, I checked the 56 volts at each amp they were right on the money. 15 volts good, 12 volts good, 7 volts good. yes I understand that something is keeping the amps from firing, but I checked most every component on the main board. my brain is fried.

[Khron]

Re: onkyo ht-r990

So wait, you're saying you're getting +/-29v (relative to the circuit ground) at the OUTPUTS of those +/-15v regulators???

And +/-13v where you're supposed to have +/-7v???

[harleyman58]

Re: onkyo ht-r990

if I take my black probe and ground it on the metal case and take my red probe and check the supply rails I get +15 and -15, +7 and -7 volts. but if I have the black probe on the - rail and the red probe on the + rail I read 29 volts and 13 volts