Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default Power switch is erratic on receiver

I picked up a used Koss HH375 receiver at a Goodwill store. It's purpose
is to power some speakers for my computer's sound. Although this is no
high powered amplifier, it does the job, and sounds 100 times better
than those cheap "amplified computer speakers".

But it has a "bug". The power switch is erratic. Sometimes I have to
push it 5 or more times to get it to "latch on". (and the same to shut
it off). Once and awhile, it even turns itself off, when in use. Worse
yet, often when I turn it on, there is no sound. I have to push the
"up/down" volume switches.

My original thought was to just never turn it off, and to put a switch
on the power cord. I soon found this will not work. If I unplug it, it's
OFF the next time I plug it in.

I have not yet opened it up, but plan to do so. But there must be a
problem beyond dirty switch contacts, because of that volume control
issue.

I should mention that this receiver was designed to be used with a
remote control (which I do not have). That tells me that the switch is
INSIDE the circuit, not just a power line toggle switch. And that's
where I tend to get lost......

On top of that, I have not found anything as far as a schematic online.

I'm a guy who has worked on a lot of tube equipment, but this modern
stuff is not my cup of tea.....

Anyone have any idea how this thing works or what to look for???
I'd like to fix it if I can, just because it has very nice sound
quality. Otherwise I'd just replace it with another amp. I did not pay
much for it, so it's no big deal, but I'll give it a shot, if I know a
little more what I am facing!

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Default Power switch is erratic on receiver

On 3/18/2017 8:28 PM, wrote:
I picked up a used Koss HH375 receiver at a Goodwill store. It's purpose
is to power some speakers for my computer's sound. Although this is no
high powered amplifier, it does the job, and sounds 100 times better
than those cheap "amplified computer speakers".

But it has a "bug". The power switch is erratic. Sometimes I have to
push it 5 or more times to get it to "latch on". (and the same to shut
it off). Once and awhile, it even turns itself off, when in use. Worse
yet, often when I turn it on, there is no sound. I have to push the
"up/down" volume switches.

My original thought was to just never turn it off, and to put a switch
on the power cord. I soon found this will not work. If I unplug it, it's
OFF the next time I plug it in.

I have not yet opened it up, but plan to do so. But there must be a
problem beyond dirty switch contacts, because of that volume control
issue.

I should mention that this receiver was designed to be used with a
remote control (which I do not have). That tells me that the switch is
INSIDE the circuit, not just a power line toggle switch. And that's
where I tend to get lost......

On top of that, I have not found anything as far as a schematic online.

I'm a guy who has worked on a lot of tube equipment, but this modern
stuff is not my cup of tea.....

Anyone have any idea how this thing works or what to look for???
I'd like to fix it if I can, just because it has very nice sound
quality. Otherwise I'd just replace it with another amp. I did not pay
much for it, so it's no big deal, but I'll give it a shot, if I know a
little more what I am facing!


I find it a bit amusing that you complain so much about the "modern
stuff". Of course you don't know much about it. Did you know all about
tube equipment when you started learning?

They make all levels of quality in computer speakers. You just have to
listen to them or at least get some specs on them before you judge them
too harshly. I have a pair of Sony's that sound nice to me. But they
use an audio cable and I prefer Bluetooth. I installed an eBay module
in one, but it quit working after a year or so. I need to get another
and see if it will work again.

--

Rick C
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Default Power switch is erratic on receiver

https://www.flickr.com/photos/kriswood/5498051786

This (bottom unit)? It was made by a division of Koss that is defunct and no longer supporting its products, in a mix of Singapore, Taiwan, China, Japan and Korea - quite a range. I am speculating given that this is an R/C unit, which typically requires special internal controls. By the way, replacement remotes are readily available from the likes of Amazon and others.

Very likely a solid-state volume control - nothing you can get to or clean. Possibly a stepper volume control which uses a small motor and a conventional VC. Those you can get to and clean.

The on/off switch is likely a latching reed relay, about the size of a large squared-off jelly bean. You would have to replace this outright. Can you say "PITA"?

Do not clean the slide controls with conventional contact cleaner. That will require a cleaner formulated to those types of controls.

It may comes to pass that with sufficient exercise, the controls will clean themselves.

If not, you will have to troubleshoot on a component level, that is part-by-part. Given its purpose, I suggest you live with its quirks as from your description, it eventually does work. By the time you are done with it, unless you are exceedingly lucky or there is a directly visible problem, it will likely not work.

Peter Wieck
Melrose Park, PA
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Default Power switch is erratic on receiver

rickman wrote: "I have a pair of Sony's that sound nice to me. But they
use an audio cable and I prefer Bluetooth."

What's wrong with running a cable? Besides,
a hard connection will always sound better
than Bluetooth, or other wireless means.

"I installed an eBay module in one, but it quit working after a year or so."

An "eBay module"? You mean you tried
to make the speakers pick up sound
wirelessly?


--

Rick C
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Default Power switch is erratic on receiver

If the switch is mechanical there is a way to wire it to be always on. Just do that, and just leave it on.

I know you can't do that with tubes or class A stuff, but a regular class AB amp will be fine. And usually it will sound better and better as it burns in. Just leave it on forever. I do with mine, and I do not see a huge electric bill or anything. They might pull about three clock radios worth of power, which is about nothing. I mean like a dollar a month if that.



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Default Power switch is erratic on receiver

On Sunday, March 19, 2017 at 4:21:16 PM UTC-4, wrote:
If the switch is mechanical there is a way to wire it to be always on. Just do that, and just leave it on.


Hmmm.. functional but no charm... Here's what he needs:

http://www.antiquesnavigator.com/d-3...te-copper.html

Four sheet metal screws and some hookup wire and he's back in business. Plus, he gets the added benefit of saying "muwahahahaha" every time he turns it on..

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Default Power switch is erratic on receiver

CRC electronics cleaner at Walmart.

ask Al for a switch lubricant

http://www.alliedelec.com/chemicals-...es/lubricants/

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Default Power switch is erratic on receiver


wrote in message
...
I picked up a used Koss HH375 receiver at a Goodwill store. It's purpose
is to power some speakers for my computer's sound. Although this is no
high powered amplifier, it does the job, and sounds 100 times better
than those cheap "amplified computer speakers".


Just get some Altec-Lansing PC speakers (I did - several pairs). The ones I
have are basic single drive units, the plastic cases are sturdy and they
sound pretty good.

One pair was thrown in with a refurb PC - the rest came from a free
recycling group.

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Default Power switch is erratic on receiver

On Sun, 19 Mar 2017 05:25:51 -0700 (PDT), "
wrote:

If not, you will have to troubleshoot on a component level, that is part-by-part.
Given its purpose, I suggest you live with its quirks as from your description,
it eventually does work. By the time you are done with it, unless you are exce
edingly lucky or there is a directly visible problem, it will likely not work.


{Quotes snipped because of line length]

Yea, it does eventually work, but it also will occasionally shut itself
off right in the middle of some music or something. There is no rhyme of
reason that it shuts off, but it does and all the LEDS and everything go
off. From what you described, I doubt I want to evne mess with it. This
is the kind of stuff I dont like working on. I may take a look inside,
but I think it's time to begin looking for another amp, and one that's
older. I prefer tube amps for an actual stereo system, but for a
computer amp, a decent older transistorized unit would be fine. This has
a radio, but I dont need it. All I need is a power amp with a AUX or
TAPE input.

I find it disturbing that Koss is out of business, I remember when they
were the top of the line for headphones.


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Default Power switch is erratic on receiver

Koss is doing just fine. Their electronics division is gone. Historically, many transducer companies, starting with KLH, AR, Advent, ADS and many others have run aground when attempting electronics. Why should Koss be any different?

Peter Wieck
Melrose Park, PA


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Default Power switch is erratic on receiver

On Wednesday, March 22, 2017 at 7:08:22 AM UTC-4, wrote:
Koss is doing just fine. Their electronics division is gone. Historically, many transducer companies, starting with KLH, AR, Advent, ADS and many others have run aground when attempting electronics. Why should Koss be any different?

Peter Wieck
Melrose Park, PA


ARE these companies from New England ?

the switch problem rests in the function. switches generally last as switches live a low stress life. except for rotaries, possibly emergency switches in mobile units, switches just slid n switch. there's a axle or pivots ? any signs of wear .... in the Gobi for 20 years ....

so if the switch is sprayed with cleaner n lubricant.... once twice three times CRC is used as a pressure flow device...the switch should resume switching.

there's one here near the floor had several doses of fruit juice. intermittent but cleaned wroks good.

I'll look for the Koss ..

KLOSS ....

https://www.google.com/#q=koss+KLH,+...STRY&*&spf=895

the forum has historians
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Default Power switch is erratic on receiver

On Wed, 22 Mar 2017 04:08:20 -0700 (PDT), "
wrote:

Koss is doing just fine. Their electronics division is gone. Historically, many
transducer companies, starting with KLH, AR, Advent, ADS


OK, now I know that.... I'm sure this receiver was just rebranded by
Koss. If I could find out who made the thing, I could probably find a
schematic for it. But how to find that out seems near impossible.

Since you mentioined KLH, the speakers I am using are KLH brand. Great
sounding for their small size.

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Default Power switch is erratic on receiver

Funny thing about this. As one who focuses primarily on legacy equipment I own one KLH Table Radio.
I own six (6) sets of AR speakers, all from the Teledyne days, all in active service from 3as through Athenas. I also own one-each of their amps, receivers and tuners.
I own an Advent 500 SoundSpace control and a 100A dual-Dolby unit (matched to my Revox A77).
I own a pair of ADS speakers out on loan.
I own three pairs of Koss headphones, including their electrostatics.
Other equipment in the inventory includes:

Revox A77, A720 & 722, B225, B215, B290
Harman Kardon Citation 16, 17, 18 & 19, ST7, ST8, HK2000 Cassette.
And several shelves of Dynaco tube and solid-state.
Main speakers are Maggies.
Multiple Sony Changers, 200 & 5 disc, all from thrift-shops.

So apart from the Revox, Sony and the HK2000, everything is from the US and from 'back in the day'. Much of it via dumpster-dives, and purchasing repair-shop leavings as my eyes and ears have always been larger than my wallet.. I did drive 1,200 miles round-trip for the Maggies, however, after a friend auditioned them in-situ. The price was that good. They are truly worth it.

Peter Wieck
Melrose Park, PA
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On Wed, 22 Mar 2017 12:19:14 -0700 (PDT), "
wrote:

Funny thing about this. As one who focuses primarily on legacy equipment I own one KLH Table Radio.
I own six (6) sets of AR speakers, all from the Teledyne days, all in active service from 3as through Athenas. I also own one-each of their amps, receivers and tuners.
I own an Advent 500 SoundSpace control and a 100A dual-Dolby unit (matched to my Revox A77).
I own a pair of ADS speakers out on loan.
I own three pairs of Koss headphones, including their electrostatics.
Other equipment in the inventory includes:

Revox A77, A720 & 722, B225, B215, B290
Harman Kardon Citation 16, 17, 18 & 19, ST7, ST8, HK2000 Cassette.
And several shelves of Dynaco tube and solid-state.
Main speakers are Maggies.
Multiple Sony Changers, 200 & 5 disc, all from thrift-shops.

So apart from the Revox, Sony and the HK2000, everything is from the US and from 'back in the day'. Much of it via dumpster-dives, and purchasing repair-shop leavings as my eyes and ears have always been larger than my wallet. I did drive 1,200 miles round-trip for the Maggies, however, after a friend auditioned them in-situ. The price was that good. They are truly worth it.

Peter Wieck
Melrose Park, PA

The Citation 16 is a brute of an amp. A speaker company I worked for
used them to test our speaker designs. One night a guy broke into our
factory and grabbed one of our 16s. The cops were chasing his car up
a steep hill and the amp fell out of the passenger door and rolled
down the hill. The outside damage was horrendous. We plugged it in
and it worked!

---
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Default Power switch is erratic on receiver


"Chuck" wrote in message
...
On Wed, 22 Mar 2017 12:19:14 -0700 (PDT), "
wrote:

Funny thing about this. As one who focuses primarily on legacy equipment I
own one KLH Table Radio.
I own six (6) sets of AR speakers, all from the Teledyne days, all in
active service from 3as through Athenas. I also own one-each of their
amps, receivers and tuners.
I own an Advent 500 SoundSpace control and a 100A dual-Dolby unit (matched
to my Revox A77).
I own a pair of ADS speakers out on loan.
I own three pairs of Koss headphones, including their electrostatics.
Other equipment in the inventory includes:

Revox A77, A720 & 722, B225, B215, B290
Harman Kardon Citation 16, 17, 18 & 19, ST7, ST8, HK2000 Cassette.
And several shelves of Dynaco tube and solid-state.
Main speakers are Maggies.
Multiple Sony Changers, 200 & 5 disc, all from thrift-shops.

So apart from the Revox, Sony and the HK2000, everything is from the US
and from 'back in the day'. Much of it via dumpster-dives, and purchasing
repair-shop leavings as my eyes and ears have always been larger than my
wallet. I did drive 1,200 miles round-trip for the Maggies, however, after
a friend auditioned them in-situ. The price was that good. They are truly
worth it.

Peter Wieck
Melrose Park, PA

The Citation 16 is a brute of an amp. A speaker company I worked for
used them to test our speaker designs. One night a guy broke into our
factory and grabbed one of our 16s. The cops were chasing his car up
a steep hill and the amp fell out of the passenger door and rolled
down the hill. The outside damage was horrendous. We plugged it in
and it worked!


Years ago some item of consumer electronics was reportedly rescued from the
rubble after a gas explosion destroyed a block of flats, the fact it still
worked was why it made the news.

Too long ago to remember details, but it might have been a stereo
amplifier - not a clue about make or model.

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Default Power switch is erratic on receiver

On Thursday, March 23, 2017 at 9:13:17 AM UTC-4, Chuck wrote:

The Citation 16 is a brute of an amp. A speaker company I worked for
used them to test our speaker designs. One night a guy broke into our
factory and grabbed one of our 16s. The cops were chasing his car up
a steep hill and the amp fell out of the passenger door and rolled
down the hill. The outside damage was horrendous. We plugged it in
and it worked!


The 19 is no slouch either. Same basic philosophy, two monoblocks in the same box sharing an on/off switch.

I got both my examples for pocket change - but at different times - as they both displayed the same problem - intermittent left channel.

Whatever else HK did and used with these amps, the input jacks were perhaps the cheapest they could fine, and I think that they may have specified crap directly as I could not find after-market devices of the same wretched quality.

In any case, replaced the jacks and rewired the inputs and all has been well since. Since that time, I have repaired two other 19s with the same problem.

Peter Wieck
Melrose Park, PA
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