SRM-717 Re-Cap
Aug 5, 2013 at 8:05 AM Post #31 of 41

duncan1

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This  is very interesting I like a challenge . I tested mine and both tested okay at 4.7M ohm, By removing the fuses you can test better in circuit. I agree the current shouldnt have affected them . But I have seen switch on surge take out resistors  Most of the resistors   I have come across especially in radio front ends go high. Those two resistors seem to be the only kind of that type[unless somebody has better eyesight  than me]  with capped ends. Studies of different types of caps on resistors were carried out in the UK in EW mag using special micro-ohm equipment and some were found to have a small increase in resistance over a period . The longer the higher the resistance especially high voltages employed .So the type of metal that is used for the caps[at each end] plays a part in the reliability of the resistor . I dont have the actual mag to hand but I have a good memory.It could be a combination of things that bring it about. I take it they are 500V types?
 
Aug 5, 2013 at 12:29 PM Post #33 of 41

duncan1

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Sorry to disagree but in my 717---R60/R61 are 4.7 MEG.Maybe if I give you the serial no. of the mother board it will help=PB-101/08454-0010. If your board shows different  . Then--- 1-UK and US boards are different??[not counting different mains voltage--or 2-modifications that Stax hasnt mentioned have taken place and circuit diagrams dont specify--seen this happen elsewhere--only government  equipment seems to show all mods.There is a 727-11 diagram on this website saying its a 727-11 diagram with a switch added for local/global feedback -.Some of the components numbered dont comply to my 727-11 also no input components are shown [small value caps for filter/bandwidth limiting purposes.] Whats going on Kevin?? I might be a subjective but when it comes to science and circuit design I am an objective. and can only see what a circuit board shows me. ----May I add found R63/R64 they are at the front of my board look like carbon types but they too are yellow/violet/green=4.7M ohm.
 
Aug 5, 2013 at 12:50 PM Post #35 of 41

duncan1

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Apart from the "pb" being in capitals ---yes Kevin. Can I also say that it-the 717 and the 727-11 were both bought from the one and only[as far as I know] authorized Stax dealer in the UK namely=Symmetry-quote-Authorized Distributor in United Kingdom-end quote.
 
Aug 5, 2013 at 1:10 PM Post #36 of 41

shipsupt

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Make it four times; it was the same resistors giving me the intermittent fault.  
 
60/61
 
Quote:
its always the last thing you do that fixes the problem.
 
no reason those resistors should burn up, they are running at half power.
I think this is the third time I have seen problems with those 2 resistors.
And its always both of them.

 
Aug 5, 2013 at 1:37 PM Post #37 of 41

duncan1

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Shipsupt-That makes sense to me --attached-one end to each HV fuse. We both live in the UK maybe the US has mods to their -717. But thats not very good technical business as applied to Stax.  Making different versions [apart from mains supply] causes confusion and would mean their standard circuit  diagrams dont apply.   
 
Sep 24, 2014 at 7:51 PM Post #38 of 41

Interben

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Hi guys,
I know this is an old thread but I am entering the world of Electrostatics and am looking at the 717 for my solution.....
 
I have always loved playing with electronics and am confident to solder, replace resistors, caps etc but I really have no idea regarding how to test and measure circuits.
 
My question is can the 717 be easily converted from 110 to 240V?  Would it require a new transformer? I note the caps are 400V so does that mean the circuitry would be fine with the change?
 
I would also like to thank you all for this thread... As I said before I love to tinker and could see myself trying to perform the mods as described in this thread in the future .......
 
Thanks
 

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