lost one channel on an old Onkyo amplifier

[Tim R]

I have an old and extremely heavy Onkyo stereo amplifier that I use in the basement in my workroom. I bought it years ago at a thrift shop and it's worked well for years.

Now only one channel works. I've tried it on A and B speakers and mono, doesn't matter. Sound comes out of only one side.

Is there anything simple this is likely to be, or is it time to set it out by the curb? (in my neighborhood nothing makes it to garbage day)

There was a thunderstorm and power outage this week, but I'm not sure if it failed before or after.

[Shaun]

"Tim R" wrote in message
news:425fdc8f-20ed-40b2...@googlegroups.com...

I've fixed my 5 channel Onkyo amplifier years ago; It was just cracked
solder joints between the RCA connectors and the circuit board. I would
suspect in your case that you may have a failed transistor or two. You have
the other channel to compare the reading too. Remove the power transistors
(mounted on heat sinks) and check them with an DMM on diode check, then
compare them to the pair from the working side. It is probably worth the
effort since Onkyo has a good name for mid quality Hi-Fi equipment. Then
look on the internet for replacements or Substitutes and get a matched pair.

Shaun

[Trevor Wilson]

**Since you have declined to provide any useful information, I doubt you
can be helped. A model number would be nice. Some old amps are well
worth resurrecting. Some are not. Given that yours is "old and extremely
heavy" (how much is that - 10kg or 50kg?), then maybe it's worth fixing.
Or not.



--
Trevor Wilson
www.rageaudio.com.au

---
This email has been checked for viruses by Avast antivirus software.
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[Tim R]

On Sunday, August 9, 2015 at 12:21:40 AM UTC-4, Trevor Wilson wrote:
>
> **Since you have declined to provide any useful information, I doubt you
> can be helped. A model number would be nice. Some old amps are well
> worth resurrecting. Some are not. Given that yours is "old and extremely

Sorry about that, the model number was on the back.

It's an Onkyo TX-3000. I bought it for $5 at a thrift store years ago, and still remember carrying it to the car several blocks away.

I just looked it up, the weight is 11.4 kg. The date is given as 1981, which may make it almost 35 years old.

I haven't opened it up to look yet.

[Trevor Wilson]

**I guess our definition of "heavy" is very different. 11.4kg is not
heavy. 50kg is heavy. Either way, your Onkyo is an attractive,
retro-styled receiver. Keep an eye on eBay for typical selling prices.
That will provide an indication as to the viability of repair. Your
first option should be to obtain a service manual, or schematic and
perform the usual fault-finding process.

[Mark Zacharias]

"Trevor Wilson" <tre...@SPAMBLOCKrageaudio.com.au> wrote in message
news:d2q4nj...@mid.individual.net...

The OP has no technical expertise. Other than the 4 amp fuses on the rear of
the unit, his chances of fixing it himself are low.

Having said the obvious, if there is sound at that channel of the volume
control, the fault is most likely an output IC (STK0050II) or driver IC
(STK3062).

New old stock replacements are rare and Chinese counterfeits are likely to
perform poorly if at all.


Mark Z.

[Wolfgang Allinger]

On 10 Aug 15 at group /sci/electronics/repair in article 55c8844e$0$3646$4c5e...@fastusenet.org

<mark_za...@labolgcbs.net> (Mark Zacharias) wrote:

>"Trevor Wilson" <tre...@SPAMBLOCKrageaudio.com.au> wrote in message
>news:d2q4nj...@mid.individual.net...
>> On 10/08/2015 7:13 AM, Tim R wrote:
>>> On Sunday, August 9, 2015 at 12:21:40 AM UTC-4, Trevor Wilson
>>> wrote:
>>>>
>>>> **Since you have declined to provide any useful information, I
>>>> doubt you can be helped. A model number would be nice. Some old
>>>> amps are well worth resurrecting. Some are not. Given that yours
>>>> is "old and extremely
>>>
>>> Sorry about that, the model number was on the back.
>>>
>>> It's an Onkyo TX-3000. I bought it for $5 at a thrift store years
>>> ago, and still remember carrying it to the car several blocks away.

>The OP has no technical expertise. Other than the 4 amp fuses on the
>rear of the unit, his chances of fixing it himself are low.
>
>Having said the obvious, if there is sound at that channel of the
>volume control, the fault is most likely an output IC (STK0050II) or
>driver IC (STK3062).
>
>New old stock replacements are rare and Chinese counterfeits are
>likely to perform poorly if at all.

Some amplifier have Relais just to suppress the PWRon `plopping`.

Find out, if the Onkyo has it.

The contact (material) often is bad selected, designed, dirty or
broken...

Knocking these Relais while powered with the grip of a screwdriver from
different direction just to see if gives some scratching noise.

Some relais may be opened easily and press/move/clean the contacts.
Or find out the layout position of the contact and bridge them for the
faulty channel.


Saludos (an alle Vernünftigen, Rest sh. sig)
Wolfgang

--
Wolfgang Allinger, anerkannter Trollallergiker :) reply Adresse gesetzt!
Ich diskutiere zukünftig weniger mit Idioten, denn sie ziehen mich auf
ihr Niveau herunter und schlagen mich dort mit ihrer Erfahrung! :p
(lt. alter usenet Weisheit) iPod, iPhone, iPad, iTunes, iRak, iDiot

[Tim R]

On Monday, August 10, 2015 at 7:00:33 AM UTC-4, Mark Zacharias wrote:
> The OP has no technical expertise. Other than the 4 amp fuses on the rear of
> the unit, his chances of fixing it himself are low.
>
> Having said the obvious, if there is sound at that channel of the volume
> control, the fault is most likely an output IC (STK0050II) or driver IC
> (STK3062).

This is true. I can do some minor component replacement but am lost troubleshooting, so the chances of finding the right component are small.

Just to be clear I've described the problem, here is what happens: sound comes out of one side of the speaker connections but not out of the other, regardless whether I push the mono or stereo utton, regardless whether I use speakers A or speakers B.

My question revolved around whether an Onkyo is worth fixing (sounds like yes), is easy to fix (sounds like no) and whether a 35 year old piece of equipment has multiple other parts at the end of life.

[dansabr...@yahoo.com]

> My question revolved around whether an Onkyo is worth fixing (sounds like yes), is easy to fix (sounds like no) and whether a 35 year old piece of equipment has multiple other parts at the end of life.

This should be a simple fix. Where are you located? There are some of us that would be willing to repair it for you I'm sure at a reasonable cost.

Dan

P.S. I have NOS STKs available if the ones listed up thread are accurate.

[Tim R]

On Monday, August 10, 2015 at 8:35:33 AM UTC-4, dansabr...@yahoo.com wrote:
> > My question revolved around whether an Onkyo is worth fixing (sounds like yes), is easy to fix (sounds like no) and whether a 35 year old piece of equipment has multiple other parts at the end of life.
>
> This should be a simple fix. Where are you located? There are some of us that would be willing to repair it for you I'm sure at a reasonable cost.
>

Central Virginia, south of Richmond.

[Cydrome Leader]

Start simple.

Check the speaker fuses on the rear. Swap good for bad to make sure the
amp module isn't also blown if that's an issue.

[Shaun]

"Mark Zacharias" wrote in message
news:55c8844e$0$3646$4c5e...@fastusenet.org...

If it has Output ICs instead of discrete components; just throw it out, they
are not worth fixing any way.

I would have thought that on older model Onkyo would be discrete.

Shaun

[pf...@aol.com]

On Monday, August 10, 2015 at 2:24:32 PM UTC-4, Shaun wrote:

> If it has Output ICs instead of discrete components; just throw it out, they
> are not worth fixing any way.
>
> I would have thought that on older model Onkyo would be discrete.
>
> Shaun

It has ICs. And unless such are readily available and/or there are valid substitutions, it is emphatically NOT worth fixing if they are blown and you would have to pay someone else to diagnose, order parts, install the parts, test and give back.

On the other hand, fuses do get weaker with age and strain. It may well be that one or another of them is blown. DO NOT rely on visual inspection to determine if a fuse is good or not. A fuse that fails from age typically does so at the solder point, and that would be invisible. Check with a VOM, or simply install new fuses. If one is visibly blown, however, try to look for a cause before plugging in a new fuse.

Also, DO check solder joints both on the input and output side. Also at any speaker switches. One simple cold-solder or broken solder joint can condemn an otherwise good component to landfill for no good reason.

http://olx.pl/oferta/tuner-onkyo-tx-3000-CID99-ID9nSKW.html This is a picture of the guts, clearly showing the driver and output ICs. From my seat and with my eyes, it looks like a STK0050-II which is an off-the-shelf item usually selling in the US$8 - 12 range, or so. Maybe even less. Search for eBay item: 121715396881 as one readily available example.

So, check for mechanical issues. Check for obvious problems such as a loose wire, poor contact at an RCA jack or output connection, the usual suspects. Check _all_ fuses. Then, if all else fails and you feel that replacing the modules would not be beyond your skills, purchase two (2) and have-at. The second one is if the 'other' one goes bad in the future. Maybe even keep a spare driver IC if you really like this beast.

I would offer to fix it, but between shipping and the 90+ days it would take me even to get around to it, you are far better off staying local.

Trevor, my heaviest tuner is 11.7 kg. My heaviest amp is just a hair under 26 kg. It's funny - my 200 WPC SS amp weighs only one kg. less than my 75-WPC tube amp at 24.9 kg.

Peter Wieck
Melrose Park, PA

[jurb...@gmail.com]

I got bad news and good news, though you already heards, it has ICs.

The good news is that if it didn't make any nasty noises, it is probably just the speaker fuse.

More good news is that if it cannot be fixed, a preamp level output can be had because the tone controls are separate from the power amp. What's more, the bad STK could be faked out to get a ittle bit more gain out of the STK3062. Not my favorite approach but would work. The 3062 is probably good, and if not there were enough of those around and not failing that it would be easier to find NOS.

I can rework it to take more modern chips. The FM is decent, has four gang tuning which is better than most. The chipset and design overall are good. All you need is a power only amp.

But change those speaker fuses first. They are usuallly under a rectangular cover on the back wiht one #1 phillips screw in the middle. They go simply from fatigue sometimes. Or if someome connecteed too many speakers to it.

Tell you this much, if you are lucky and it is just the fuse, change them both and then make sure to only use one pair of eight ohm speakers on it and make sure not to cover the vents. Keep it cool. If those STK power ICs have lasted this long they will probably last alot longer.

If they are bad I can retrofit new ICs in there. It would technically no longer be an Ohky amp but you still would have the Onkyo tuner and preamp. It would be easy to get pre level outputs but putting the amp in there would mean you can still use its internal speaker switching.

I cna do it but shipping from there to Ohio and back would not be cheap and you have to pack it as though it is going to be handled like a basketball, because it is. I retrofitted a Mitsubishi Interplay system for a guy in Pittsburgh and the round trip was $300, AND THEY UCKED IT UP ! It was insidious damag3 so a claim would be just too much trouble, plus what wuld they pay ? So we met at the state line and I fixed it and met again and everyone is happy. Shipping was rally high because that is a heavy unit with a (half decent) vertical linear tracking turntable. Your unit would not be as much, but you are really too far to meet.

The other thing is that on eBay they go from about $100 down to $32. But there is only one for sale now and it is for repair or parts. The $32 one, some people are not too bright and have a really short auction and don't put a reserve on it. Boss just did that with a vintage echoplex machine, I'll have to have a talk with him about that...

If you need and want this done, probably around a hundred bucks plus parts (probably fifty), and shipping both ways should be about a hundred. That is more than the thing will bring. If you like it allt then it is worth it. If not, don't throw it out, sell it to someone. Even for parts. Sometimes a knob can fetch $25. To get really good money you have to part it out and list all the goodies separately on eBay, or let someone do it.

You can probably get decent money out of the good STK, if one is bad.

So don't just throw it in the trash.

[jurb...@gmail.com]

>"P.S. I have NOS STKs available if the ones listed up thread are accurate. "

Do you happen to have an STK0100 II and if so, how much ? I am already fitting one into a Fisher CA-800 that used to have 0080s in it. The one I got I know is NOS. It might be nice to do both at the same time because I have to do some things to the heatsink because the 0100 is bigger.

[dansabr...@yahoo.com]

On Monday, August 10, 2015 at 6:47:54 PM UTC-4, jurb...@gmail.com wrote:
> >"P.S. I have NOS STKs available if the ones listed up thread are accurate. "
>
> Do you happen to have an STK0100 II and if so, how much ? I am already fitting one into a Fisher CA-800 that used to have 0080s in it. The one I got I know is NOS. It might be nice to do both at the same time because I have to do some things to the heatsink because the 0100 is bigger.

I have (2) STK0080II and (2) STK0100II available.

Dan

[Tim R]

On Monday, August 10, 2015 at 3:17:50 PM UTC-4, pf...@aol.com wrote:

> On the other hand, fuses do get weaker with age and strain. It may well be that one or another of them is blown. DO NOT rely on visual inspection to determine if a fuse is good or not. A fuse that fails from age typically does so at the solder point, and that would be invisible. Check with a VOM, or simply install new fuses. If one is visibly blown, however, try to look for a cause before plugging in a new fuse.
>

I am reasonably smart but capable of horrendous brain cramps for no apparent reason. This got suddenly much worse after my 60th birthday and I am somewhat concerned.

However, I am not yet stupid enough not to check the fuses. They are fine.

Okay, I admit, I did not know there were speaker fuses on an amp, I've never blown one. But when I turned it around, I saw the panel that said Speaker Fuses and I opened it and checked them with a VOM. I used my cheap Radio Shack digital, but when in doubt I always reach for the Simpson, old reliable 260D.

and then

I got to thinking.

I was pretty sure this was the amp that didn't have a balance control. I remember how much grief that caused me when I really needed one.

So, that's the one thing I didn't check.

What if I'd remembered wrong? What if one of the kids moved the PC and bumped the balance knob?

CRAPCRAPCRAPCRAPCRAP!!!!!!!!

The balance knob was all the way to one side and when moved back to center, the Onkyo is fixed.

When I had the Onkyo off the table, I'd replaced it with a Pioneer home theater unit. I am so glad to get rid of that one, it really sucked compared to the Onkyo. I am not really an audiophile - I can tell the difference between good and bad styluses, good and bad speakers, but never was able to tell much about the amplifier. But the Onkyo is head and shoulders above the Pioneer.

[Rheilly Phoull]

"Tim R" wrote in message

news:bac45eb6-f681-4ec4...@googlegroups.com...

Well mate you would not be alone, there wouldn’t be many casual repairers
that haven't done similar !!

[Dave Platt]

In article <bac45eb6-f681-4ec4...@googlegroups.com>,

Tim R <timot...@aol.com> wrote:

>What if I'd remembered wrong? What if one of the kids moved the PC and bumped the balance knob?
>
>CRAPCRAPCRAPCRAPCRAP!!!!!!!!
>
>The balance knob was all the way to one side and when moved back to center, the Onkyo is fixed.

There was much rejoicing!

I recently had a bad scare with the FM service monitor that I had
dragged down to our city's ARES/RACES ham shack. I'd been asked to
run a full check on all of the UHF/VHF radios, and the service monitor
wasn't "seeing" any signal on any frequency. When I switched it to
"generate" mode, there was no output at all.

I thought the frequency synthesizer circuit had died, and resigned
myself to hauling it home for a full investigation and repair.

Just as I was finishing the box-it-up process, I thought "Hmmm... one
thing I ought to double-check..." and I turned it around and looked at
the back panel.

Sure enough... the tiny little time-base switch was set to
"external". The last time I had used it, I'd been feeding it a 10 MHz
reference signal from my rubidium oscillator, and had forgotten to
switch it back to its internal time-base when I was done.

Threw the switch to "internal", checked it again, and the synthesizer
was working fine.

I gave myself a slap on the wrist for not resetting it to normal
operation after the previous usage... and breathed a sigh of relief
that I'd discovered the error before I went all the way home with it.

[MJC]

In article <3mpp9c-...@coop.radagast.org>, dpl...@coop.radagast.org
says...

> I gave myself a slap on the wrist for not resetting it to normal
> operation after the previous usage... and breathed a sigh of relief
> that I'd discovered the error before I went all the way home with it.

Now if there had been a sensible warning light on the front panel you
might have noticed earlier...

Mike.

[jurb...@gmail.com]

>"The balance knob was all the way to one side and when moved back to center, >the Onkyo is fixed. "

I've seen worse. That just happened to me and I am a pro. I had a similar unit, in fact an Onkyo TX-2500 which is a bit older, has no digital/quartz lock thingie in it. It DID have a blown speaker fuse, blown by fatigue actually. I put that in and I got one channel. Oh shit. So I take the bottom off and stat checking. The silent channel has no input to the power amp board, I trace it back to the tone board and sure enough it is losing it there. I get all the way to the output end of it and I see the transistors are amplifying just fine, but is dropped across a resistor. OK, open resistor, right ? Nope, checks fine. Must be a short circuit.

Guess how balance controls work. They short out the audio ! (that is how the get max gain in the center position, except a few which use a dual pot) Open a window ! BRAIN FART !

>"I am not really an audiophile - I can tell the difference between good and >bad styluses, good and bad speakers, but never was able to tell much about the >amplifier. But the Onkyo is head and shoulders above the Pioneer. "

I suspect you of being a closet audiophile. Or maybe you are in denial. lol

Really, it doesn't take a ten grand system. It doesn't have to be 30 years old. You might want to browse around audiokarma. Some interesting reading not only about how stuff sounds different even with the same power and specs, but WHY. If you're inclined you'll probably find some interesting threads there. Lately there have been discussions about damping factor and what KIND of distortion different amps or other equipment has and how well you can hear this or that.

[jurb...@gmail.com]

How much and how far are you from Cleveland, Ohio ? I'll have to see if the guy ants to spend the bucks as well. Hopefully you don't wnat so much for them we have to put the money in escrow. I have had good luck with people on Usenet so I wouldn't mind trusting and just sending you a postal money order. (they are not forged because there is an 800 number you can call to verify them) I don't have a Paypal account but I know someone who does if you have to be paid that way.

[jurb...@gmail.com]

>"There was much rejoicing! "

My cohort and I sometimes buy used scopes from this surplus place on the east side. (I know most people don't mention that but us old west siders do around here)

Got a couple of pretty good deals, not extremely great scopes but usable for audio and a few other tings. Anyway, then people don't really know scopes ad we found that some of them, THEY don't know how to get a trace on them. Like setting them to auto trigger, or free run if it has it. Picked up a nifty Tek 422 with the battery option. I intend to replace the batteries with more modern ones but I am sure I am going to have to build the charging circuit. I might see about an of the shelf solution or possibly get the circuitry from an old laptop. I would hav to probably cut part of the motherboard or something, if that is even possible, and then most likely regulate the 19 volts down to 12, pretty sure it is 12.

And we got a Tek 7834 that used to cost more than a house for like $24. That tone however has a slight HV regulation problem which I will eventually get to. the main worry about that is that it is a big HV divider resistor. but then modification is my middle name for a reason. There is almost always a ay, andf the other surplus place (slightly farther, they are on the west side of the next place)has kagillions of old resistors, probably of every value ever made. And I mean 100.1 meg, 100.2 meg, you know. OK, I am exaggerating, but not that much.

[jurb...@gmail.com]

>"Now if there had been a sensible warning light on the front panel you
>might have noticed earlier... "

Things like that irk me. YEARS worth of Tek stuff with no power light. Some have a little window that opens to reveal a light colored piece of plastic. Ridiculous. Same with these older Wavetek generators. Muy biddy has a 103 and I have a 111, they also lack a power light.

Can't even tell if the thing is plugged in, and that is important sometimes, depending on how your bench is set up. If you are out in the field it is even worse.

Don't pick on our old equipment, at least it doesn't run Windows !

[mcurr...@gmail.com]

Try the fuse. I had same problem on a 80s TX 2500. It was one of the fuses. Replace both.

[John-Del]

On Thursday, April 2, 2020 at 3:14:58 PM UTC-4, mcurr...@gmail.com wrote:
> Try the fuse. I had same problem on a 80s TX 2500. It was one of the fuses. Replace both.

That was 5 years ago. Also, he said it was just the balance control mistakenly rolled over to one side.

[thekma...@gmail.com]

John-Del wrote:

>That was 5 years ago. Also, he said it was just the
>balance control mistakenly rolled over to one side.

________
If so, then the only issue with this amplifier was lack of basic trouble-shooting.

[Tim R]

I'm still here, the Onkyo still works, at least as of last night.

Annoyingly, now moving the volume control causes some fuzz and one speaker drops out, but usually comes back with a few rapid twists. But the sound quality is good.

[peterw...@gmail.com]

On Tuesday, April 7, 2020 at 10:52:42 AM UTC-4, Tim R wrote:

> Annoyingly, now moving the volume control causes some fuzz and one speaker drops out, but usually comes back with a few rapid twists. But the sound quality is good.

Lack of basic troubleshooting, and, apparently, basic maintenance.

Clean the controls, starting with the VC, then all other pots and switches. Should be good for another 5 years after that!

[Ron D.]

Just don't get bit by the intermittent fuse. I got bit 2x. Test fuse with ohmmeter. Fine. Put fuse in circuit. Circuit doesn't work. Test voltage across fuse-120V What? Had schematics.

Fuse was bad.

Device was a Decwriter II 300 baud hard copy computer terminal. We had changed most of these fuses to circuit breakers.

[Ronald]

On Saturday, August 8, 2015 at 11:15:10 PM UTC-4, Shaun wrote:
> "Tim R" wrote in message

> news:425fdc8f-20ed-40b2...@googlegroups.com...
> I have an old and extremely heavy Onkyo stereo amplifier that I use in the
> basement in my workroom. I bought it years ago at a thrift shop and it's
> worked well for years.
>
> Now only one channel works. I've tried it on A and B speakers and mono,
> doesn't matter. Sound comes out of only one side.
>
> Is there anything simple this is likely to be, or is it time to set it out
> by the curb? (in my neighborhood nothing makes it to garbage day)
>
> There was a thunderstorm and power outage this week, but I'm not sure if it
> failed before or after.
> I've fixed my 5 channel Onkyo amplifier years ago; It was just cracked
> solder joints between the RCA connectors and the circuit board. I would
> suspect in your case that you may have a failed transistor or two. You have
> the other channel to compare the reading too. Remove the power transistors
> (mounted on heat sinks) and check them with an DMM on diode check, then
> compare them to the pair from the working side. It is probably worth the
> effort since Onkyo has a good name for mid quality Hi-Fi equipment. Then
> look on the internet for replacements or Substitutes and get a matched pair.
>
> Shaun
Only a m5160 other than what I've wrote to the military why would a amp play on both yet not just one both channels work just not at the same time simultaneously.. bull shit

[root]

Ronald <ronaldb...@gmail.com> wrote:

I've had two Onkyo receivers in the past. Strange things happened with them such
as FM not working, one or the other channel would go out. In each case
I put the receiver on a shelf and bought another. The first time it happened
I had replaced the Onkyo with a newer Onkyo. After a while the new Onkyo
flaked out and I bought a Denon. Then for some reason I connected the
original Onkyo up and everything worked. After a while I tried the same
thing with the second Onkyo and it also worked. My conclusion is that
if you unplug the Onkyo and leave to so for several days it heals
itself.

YMMV

[Allodoxaphobia]

Since you're replying to a NINE-YEAR-OLD posting,
I'd bet the OP's problem is now solved.

[root]

>
> Since you're replying to a NINE-YEAR-OLD posting,
> I'd bet the OP's problem is now solved.
>

I'm here to help.