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Carver C-1 Sonic Holigraphy issue

SteveHammond

SteveHammond

Beautifully Restored by the grace of God!
Hello everyone, first post. I have a carver C-1 which I did the billDmod on and it sounds excellent! BUT, if I engage the sonic holography circuit all I seem to get it white noise. I replaced not only the two 4136 opamps as part of the mod but also replaced the eq opamp with the newer cimmaron technologies opamp and replaced all carbon film with metal film resistors. Long story short, I was just wondering if anyone else experienced this “white noise” or not? It did the same thing before the mod as well. Any and all help is greatly appreciated and thank you in advance.

Best Regards,

Steve
 
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Welcome to AK Steve
Do you have any testing equipment? Like an o' scope and an audio signal generator?
 
I’ve got a few pieces of testing equipment, I just haven’t been able to track my problem down and I’m baffled at this point. I’ve even tried the sling blade approach “it ain’t got no gas in it” but still come up with nill.
 
Have you tried injecting a signal in and find where the signal disappears and white noise begins?
 
avionic said:
Have you tried injecting a signal in and find where the signal disappears?
Click to expand...
I haven’t at this point, my question was more of a poll to see if anyone else has had this specific problem and maybe find an easier approach. Injecting a signal and tracing the signal is a good approach although if it’s producing a signal be it white noise would that be in vain? It’s just a curiosity statement.
 
I am in no way any type of expert diagnostician by any stretch of the imagination, actually diagnostics are not my strong suit.
 
I've done a a couple C1BD's.
Neither exhibited the issue you describe, sorry.
I'm not great at diag either (don't understand most of the circuits) so I can't help much more than to say, remember "divide and conquer".
I'm working on an m200t right now, and it's not so bad since the problem is localized to one channel.
But I also have a 1.0t and I just can't figure it out, what with that feedback from the outputs thru the triac back to the primary of the transformer - dinging hard to divide and conquer. I've failed on this one.
 
First thing I'd check is that all the new parts are oriented correctly. Not that hard to put an IC or cap in backwards ...

** Last Carver piece I upgraded was an H9aV. That had the power supply rebuilt, and all the ICs were replaced with real TI chips instead of the Malaysian ones that were installed at the factory. Also added a couple Burr Browns in strategic locations and some bypassing as needed. Excellent results and well worth the effort!

H9-AV-after.jpg
 
Thank you all for the reply’s and to answer them acccordingly, I do have the service manual and schematics as well as having double checked myself numerous times on component install. The thing I just don’t get is that it was doing this exact thing BEFORE the mod? And yet I changed that particular op amp?
 
First carefully measure your opamp's supply voltages on IC's 1,2,3,4 & 5. Pin 7 is +12 vdc and pin 11 is -12 vdc..
 
If it was doing the same thing before the mod, you may be attacking the problem from the wrong angle. Here, I'd suspect a bad line level connection or weak ground, or even a dirty switch. Try cycling those several times and see if you can get it to fart. Even if you haven't touched any of that stuff ... but maybe you bumped an already dry or brittle connection. I usually throw in an oops moment or two myself when poking into tight spaces.

The RCA jacks Carver used are also pretty bad. I'll usually replace those.

back-panel.jpg


Just pay attention to polarity, as Carver had some fun with that too.

PS - if any of that works, don't consider what you've already done a waste of time. Good experience if nothing else, and the mods DO make these things sing ...
 
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