Roger Grodinsky Research Model Five High current amplifier info - diyAudio
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Old 11th February 2009, 07:28 PM   #1
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Default Roger Grodinsky Research Model Five High current amplifier info

I am attempting to troubleshoot a Robert Grodinsky Model Five High Current power amplifier. I have accessed the various vintage manual sources and no one has anything on this Beast or any other RGR products (There was a model four preamplifier too). The company (Robert Grodinsky Research) is no longer in existence and the founder is deceased. His designs are quite unorthodox and it appears that there was little or no product support from RGR. I suspect that customers had to return failed product to RGR for repair as there seems to be no service info in existence.
Does anyone here have any service information on this amplifier?

Even a schematic would be a big help!

The unit is constructed in a manner that makes it nearly impossible to access above or below the circuit boards without MAJOR disassembly. Also, there are no parts designations on the circuit boards. Obviously, repairability was not a consideration in the design of this amplifier.
Still, it looks like it has potential and I would like to get it going just to hear how it sounds.

Any info would be much appreciated and I would reimburse any reasonable expense in getting it to me if needed.
Tuck, 2chanman.
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Old 12th February 2009, 04:09 AM   #2
thejohn is offline thejohn  South Africa
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Location: Cape Town, South Africa
Hey, I know the feeling! I have a Model 5 and two Model 4's.

I started a thread here a while ago and didn't get much response - hopefully someone, somewhere has a Model 5 Schematic.

I have the Model 4 schematic that was sent to the previous owner by Mr Grodinsky in 1981! Hand -drawn photostat copies. I've been meaning to get them scanned and cleaned up.
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Old 13th February 2009, 04:37 PM   #3
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Quote:
Originally posted by thejohn
Hey, I know the feeling! I have a Model 5 and two Model 4's.

I started a thread here a while ago and didn't get much response - hopefully someone, somewhere has a Model 5 Schematic.

I have the Model 4 schematic that was sent to the previous owner by Mr Grodinsky in 1981! Hand -drawn photostat copies. I've been meaning to get them scanned and cleaned up.
to thejohn:
Thanks for your response. It looks like the only way I am going to get this orphan going is to laboriously remove and test individual components. I have narrowed down the trouble area, but it is impossible to get at either side of most of the circuit boards to probe circuit points without tearing the whole thing apart. Many of the semiconductors (such as the driver transistors) are obsolete. It is questionable whether it is worthwhile to go to as much trouble as this project is going to take. I think it was unethical and irresponsible of Grodinsky to let this non-supportive situation exist.
If you ever do come by a schematic for the five, please let me know.
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Old 14th May 2010, 07:08 PM   #4
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Default Schematics for RGR

I did try to have a friend contact RG's son, but there were no schematics
in his house when they were closing it in spring 2009. So, will have to
do some posts around Chicago area in case some of the engineers who
worked for him saved some of the schematics. Otherwise, its a tedious
task to document the plug in boards of the preamp. And, the power amplifier
would be worse. His patents do explain how the phono preamp works
and there was an input capacitor patent for the power amplfier.

norm
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