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Help diagnosing receiver issue

 

New member
Username: Cscrum

Fort Worth, Texas United States

Post Number: 1
Registered: Mar-15
I have a Sony SDR-DH700 Receiver. Recently we had a very brief power outage like 3 seconds and then everything came back on. After this, the receiver would pass video signals, but no audio. I pulled the top, and pulled and tested all the fuses (1 fuse on the power input and two on the output). Everything tested fine, so I put Ait back together and plugged it back in and to my surprise everything worked. However a couple days later, the sound got real choppy like I had an intermittent speaker connection. I shut the power off and when it came back on, no sound again. I repeated the earlier steps, but this time, still no sound. Am I screwed or does anyone know of what could be the problem other than a blown output stage? What is strange is that it was only running 2 channels, but all channels seem to be affected. I get nothing from the center or surround channels in addition to the two primary channels. The rec is capable of biamping and I set it to that mode to see and still no joy.

Thanks!
 

Gold Member
Username: Magfan

USA

Post Number: 3231
Registered: Oct-07
Cam,
Nobody is going to be able to diagnose this without doing some tests. You were Zorched when the power did whatever. Surge or simple brownout? The lowest power devices in the PREamp part of the receiver are vulnerable.
This beast probably has IC style output devices, not discrete parts.

If this is more than 4 or 5 years old, SOME parts, which are proprietary, will be difficult to find. OTHer parts are common and will be available for decades to come.

A tech will probably charge you to diagnose the problem BUT waive these fees IF you elect to fix it.
In any event, I'm sorry to report, you may have simply had rotten luck.

My Power Conditioner will shut off the power if it drops below 95v or exceeds 135v. And has the usual surge protection.
You may consider such a device as 'cheap insurance'

That being said, the POWER COMPANY may actually pick up the tab for the fix! We had a brown out at my house. (pre power conditioner) which took out my amplifier. I'm talking a 15 amp fuse! I talked with the power company and was able to tell them the EXACT date / time and the nature of the event.
'Send us the bill after you get it fixed'.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 18041
Registered: May-04
.

All "sensitive electronics" should be running off a decent surge protector. Audio equipment qualifies as "sensitive electronics".

Fuses operate by a value of Amperage being drawn over a determined amount of time. They simply cannot react fast enough in most cases to a power surge from the incoming AC line. You need a "clamping type" device which reacts much faster than a fuse. When you replace your receiver, add a surge protector. Panamax makes some of the most effective devices for the dollar.

More than likely the control ic was fried by the surge. Could be some of the foil traces on the circuit boards have been lifted or even broken. Typically the cost of repairs will exceed the value of the item after a surge has occurred. Most shops are hesitant to even take a fee for an estimate of costs when you say your unit was the victim of a surge.

However, if you can find someone willing to look at a Sony receiver, ask for an estimate of costs before you OK any repairs. Sony tends not to allow local shops access to their repair manuals or proprietary parts so you may be in a tight place here. Regional Sony service Centers may mean you need to ship the receiver both ways at your expense adding to the overall costs and down time.

According to Cnet, this was a fairly inexpensive ($299 MSRP) receiver in 2009. HT receivers have limited life spans to begin with. IMO there's no sense in repairing an inexpensive, six year old HT receiver. If that's the case, skip the repair estimate and go directly to buying a new receiver while recycling your old one. Add the decent surge protector to the new system.


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Gold Member
Username: Magfan

USA

Post Number: 3232
Registered: Oct-07
300$ in 2009?
No way this is going to cost less than half that to FIX, if possible at all.

Sounds like time to cut losses, invest in a NEW receier in the 400$ to 500$ range AND a good surge protector, preferable with features as I discussed in my post, above.

My over / under voltage protection has tripped 2X in the last decade+
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 18042
Registered: May-04
.

The "silent killer" of electronic devices is the near constant under/over Voltage conditions which result from a larger and larger number of users being tied to the same service inlet from the power provider. You should also protect against the surges created by large appliances; refrigerator, washer, drier, dishwasher, HVAC systems etc. Unfortunately, even those appliances in your neighbor's house can inject noise and create a momentary surge since each house on one transformer in the alley will share a common grounding system.

All of these smaller hits taken by your HT system reduce the life of the system and make the devices more susceptible to failure when a larger surge occurs. Don't cheap out on the AC conditioner. It should even improve the picture quality on your monitor.


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Gold Member
Username: Magfan

USA

Post Number: 3233
Registered: Oct-07
Jan,
I just reported EXACTLY THOSE results of the addition of a power conditioner many years ago. TV? All the little 'flecks' of white went AWAY 100%. When an input was removed the screen got BLACK with no artifacts of noise whatsoever. Fine!

I also had a change in the STEREO which was tough to put into words, but sounded like a blacker background and the image changed enough to warrent a slight reposition of my panels. My Carver Cube didn't MIND being plugged into the Hi power outlets but others report a 'sucking out of life'. When I changed to a Rotel RB1070, now THAT amp hated the power conditioner but was still underpowered even straight to the wall.

I was mocked by those who NEVER experienced such a thing and supported by someone who HAD. Go Figger.

One point needs to be made about ALL power strip and HT style surge protection devices. They ALL use a device called a MOV. Metal Oxide Varister. These devices are like shock absorbers. They only last SO LONG. Than? No More Protection. ONE huge surge? The death of '100 cuts'? Ends up with NO protection. There is some good AND bad news here, however. While they DO wear out, they also are DIRT CHEAP. Commoditiy cheap, even. And since they are non-polar, you just put the NEW where the OLD were. A competent DIY guy should be able to handle this task while a tech charging for an HOUR should be able to do even the most complicated power conditioner.
Places like Florida with your basic lightning storm 6 days a week ALL summer may even benefit from a WHOLE HOUSE surge protector.
Surge protectors should be either replaced for cheap ones, which long term are NOT worth it due to limited protection or REBUILT with new MOVs on the basis of how much stress they've been under, depending on original cost / value. AND the amount of protection in 'joules', a measure of energy equal to 1 amp across 1ohm for 1 second.

The over / under voltage protection on my device is NOT 'instantanious' but rather good for sags and bumps lasting a second or MORE, at which time it'll cut off the juice to everything connected.

My Panamax, which was in the 1000$ class a decade ago, ALSO has an isolation transformer which is perfect for ALL the low power devices used in a HT setup from a CD player to a preamp.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 18043
Registered: May-04
.

Not all AC conditioners/surge protectors employ MOV's. Not all AC conditioners are functional surge protectors. And not all surge protectors serve to clean up the AC line. MOV's are extremely common in the lower cost devices and even in a few upper end items. They do wear out and they can introduce increasing amounts of noise into the AC waveform as they age. Sort of defeats the purpose in many cases.

I don't think I'd use, say, a Panamax on my main audio system but they sure go on my video/HT system along with a dedicated earth ground. Too many AV components still have two conductor AC plugs which immediately cut the surge protector's effective clamping Voltage in half. When there is no separate ground plane to work with, the surge protector essentially must wait for the surge to work its way through the component to retrieve it on the neutral/ground return side of the plug. A super fast clamping time diminishes the potential damage but still might allow a large enough surge - say, a lightning strike - to get through and fry a few components.

Once again, wouldn't some pro standards be nice in consumer audio/video?

I really haven't kept up with the technology of late but it was common in earlier days to use a very large, high quality isolation transformer feeding to a series of filter caps. Many objectivists will tell you, not totally incorrectly either, all you really need is a large industrial quality isolation transformer with decent specs and forget all the voodoo mumbo-jumbo of the high end audio world.

PS Audio's AC conditioner technology regenerates the incoming AC waveform. It is basically, as I understand it, a very sophisticated power amp which feeds AC forward and has massive storage capacity for high current delivery on demand or sustained. I suspect there are several other technologies in use in the stratosphere of pricing.

How long a surge protector will be useful is up to the individual situation. Those small but frequent surges from appliances and such add up. Surge protectors do need to be replaced occasionally. Thing is, I know of no easy test a consumer can perform which would indicate when the MOV's have lost their joojoo. AC conditioners, separate from surge protectors, typically have a fairly infinite life span since they aren't relying on the MOV for their action.

If you thought the conditioner was beneficial, leo, I'd suggest you give the PS Audio Noise Harvesters a try; https://www.gcaudio.com/cgi-bin/store/showProduct.cgi?id=399

There are several alternatives now but the Noise Harvesters do work. I find them to be quite good plugged into an AC outlet in front of an extension box downstream (or in one primary outlet of the extension box) of a conditioner. Blacker blacks and all that good stuff. Not cheap (I bought mine when they were both cheaper and offered on a group package sale) but, if your system is transparent enough to show smaller improvements in AC quality, well worth a try IMO.



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Gold Member
Username: Magfan

USA

Post Number: 3234
Registered: Oct-07
Not exactly true, Jan.
MOV is wired between hot/neutral :: Hot/ground and Ground/neutral. (3 sets)
If you have a plug which is only hot/neutral, you are STILL protected to the maximum Joule rating of the devices. The 3rd wire not connect simply doesnt matter, except that it WILL bridge current to the ground wire and leave your protected device out of that part of the circuit.
And yes, to go thru all the combinations and permutations of Power conditioners / surge protectors and regenerators and Uninteruptible PS is somewhat beyond what I thought we were talking about. I used the Iso Transformer in my Panamax as kind of an aside. USEFUL, to be sure, but only for a few who get it and are willing to spend for it. Mine is 400va and not suitable for power amps, but perfect for all my low power stuff.

I went on another forum and was trashed after telling them I could build a DC blocker for maybe 15$ or so. I doubt a noise harvester is any more complex. Subject to seeing a schematic. I'd need to see what inductors they use!

I'd like to take my Panamax OUT of service long enough to get the MOVs replaced. And yes, the REST of what constitutes a power conditioner, inductors and other circuitry SHOULD last an awful long time.

If you think of the PSAudio 'regenerator' as a ONE FREQUENCY power amp with high headroom, you'd not be far off. It should be possible to change the output frequency, but I don't know WHY you'd want to do so, unless you had a 50hz something you wanted to power from US 60hz.

I've seen OTHER and usually very expensive surge protection technology. Spark Gap, for example, would be good for a Whole-House installation.

I'd LOVE a couple 2KVA Iso Transformers. I've NEVER heard a bad word about 'em, even from Art, who is very critical of power conditioners and such.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 18044
Registered: May-04
.

If there's no dedicated ground conductor, the surge protection device has nowhere other than the neutral line to dump excessive Voltage. Right back into the supply line to the equipment. That, as I have always had it explained to me, is the issue with two conductor plugs in three conductor surge protectors. There simply is not sufficient capacity to move the over Voltage to the ground plane by way of the MOV's. I believe if you read Panamax's literature, you'll see them mention the lowered effectiveness of their devices when a third conductor has been omitted.

When I was on the Stereophile forum, there was one member who did nothing but complain about the high cost of the equipment Stereophile recommended, even down to b*tching about a $349 NAD integrated. His claim was always that he could build the same thing, no matter what it was, for $50 worth of parts. While his claims were largely absurd on their face given $50 wouldn't have typically purchased the transformer for many products, the point we continued to make was he was unable to design the product he so detested. And he certainly couldn't bring it to market and have it be a viable product for his $50.

There were the objectivists who tore apart a Noise Harvester just to prove how "cheap" a product the audiophools were raving about. Yep, a few dollars in parts ... but a whole lot of research and trial and error before saying this would work. Backward engineering electronics is what the Japanese manufacturers did in the 1960's and they turned out cheap knockoffs of US designed equipment. Put several well known names out of business too!

If you have access to the parts and the ability to reconstruct a successful component on your own for your own use; go for it, I say. Nelson Pass sells his schematics for his fairly expensive amps for a few dollars and even helps the newbies get it built for about 1/4 the price of his own gear. But Pass also has a lot of people trying and not being able to complete the job. It's all part of how you want to go about the hobby IMO. If you want to breadboard a Noise Harvester after taking one apart, you're probably right about cost. But that's just one or two you'd have made, not an entire production line which you must ensure isn't likely to burn someone's house down.

The PS Audio AC conditioner seems to be rather unique despite being one of those "why didn't I think of that" products. Big-Big*ss transformer and humongous filer/storage facilities and the surge has been dissipated and smoothed long before the downstream electronics ever see it. Low noise, low distortion to the AC line at the output and just tremendous reserves for the electronics to work from. Once again, not overly ground breaking, just no one ever tried it before. And, unlike Edison, he didn't have to electrocute an elephant to prove his point.

George Tice was one of the first very successful AC "cleaner-uppers" back in the early '90's with his Power Block. Weighed about as much as a Mac MC2300 amp and it was essentially another instance where a massive isolation transformer and a lot of storage/filter caps in a purely passive unit showed what could be done. Outside of industrial use, I'd never seen such a large transformer in any audio system before the Tice. Naturally, once people got hold of one and looked at the insides, they were all PO'd about his price. But they hadn't thought, before Tice did, to make the very simple idea a reality.

The early bird gets the worm. The second mouse may get the cheese but by then it's usually spoiled.



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Gold Member
Username: Magfan

USA

Post Number: 3235
Registered: Oct-07
Jan, your first point is not quite correct.
The hot/neutral () hot/ground () ground/neutral are all tied together by MOV at the surge protection device.
As the breakdown voltage rating of the MOV is exceeded, current is conducted from the line in question to either the neutral or ground or BOTH since they are tied togeter at the box.
Will you suffer 'reduced' capacity as a result of a 2 prong connector? Sure. But SOME good protection trumps NO protection any day of the week.
Pass is a GEM. His DIY support is legend, but I would never even TRY to build one of his amps unless somebody made a complete KIT where All I Had to do was stuff / solder boards and do the interconnect wiring in a pre-fab chasis. That's all the excuse I need to go buy that Hakko Soldering Station I've got my eyes on.

I'd never claim to be able to duplicate more complex stuff for cheap. The DC blocker I ref'd is a simple diode brige and some caps. A proper enclosure and connectors MAY actually be more than 50% of my cost to build.
It is VERY feasible to build this circuit into almost any electronic piece at the factory and for Pennies. Especially for low-current stuff like CD players or 'Universal' players.

First to market is ALWAYS nice. No Question. And if patented? You better be ready to DEFEND it in court or it is VALUELESS.
 

New member
Username: Cscrum

Fort Worth, Texas United States

Post Number: 2
Registered: Mar-15
Thanks for the responses guys. This was a purchase to satisfy my wife and kids on the primary TV they watch about 5-6 years ago. I picked it up new from Tiger direct for less than $200 so it was good while it lasted. My main audio set up is a Rotel pre-amp, Sunfire Cinema Grand Amp biamping a set of Carver Amazing Platinum Speakers. I'm not too worried, just thought if someone knew something about these that was "typical" problem and an easy fix, I could take a stab at it. With the IC style outputs, it probably wouldn't be worth the cost or time to repair. In the meantime, I have another OLD Rotel pre-amp and an Adcom 2 channel amp that actually blows the doors off this Sony anyway. The family just wanted surround sound and that was a quick and cheap way to get it. I prefer the higher quality stereo sound anyway. The surround never worked well IMO as everything was too heavy on the center channel for my liking, and stuff that wasn't encoded for surround always sounded hollow on the dialog. Thanks again!
 

New member
Username: Cscrum

Fort Worth, Texas United States

Post Number: 3
Registered: Mar-15
BTW, I did not have a line conditioner, but I did have a surge protector although it was a "cheap" one.
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