Pirx Posted November 14, 2012 Report Share Posted November 14, 2012 Hello Everyone This is my first post here. I have done some research about T1 troubles here and didn't find any topic about hot trafo. In my opinion this trafo is too hot but I don't have another SRM-T1 to check. I have removed tubes and then trafo is only warm - seems ok. Picture shows where I put temp sensor (blue wire). Did anyone had similar problems? P.S. I have just bought SR-Omega with Mk1 driver and SRM-T1 - amazing sound My previous system was SRM-727 and SR-507 and it wasn't so good. Quote Link to comment Share on other sites More sharing options...
wink Posted November 14, 2012 Report Share Posted November 14, 2012 P.S. I have just bought SR-Omega with Mk1 driver and SRM-T1. Were these on ebay from wiktor or rotkiw ? Quote Link to comment Share on other sites More sharing options...
n_maher Posted November 14, 2012 Report Share Posted November 14, 2012 There is some disturbing discoloration on that transformer, in my non-professional opinion. I would make sure that the amp is setup for the proper line voltage (assuming it's adjustable like other Stax amps) and after that get a known good set of cheap tubes to try in there. Could be that one of the 4 tubes is going bad and drawing more current than it should be. Otherwise, I don't know enough about that amp to be really helpful. Quote Link to comment Share on other sites More sharing options...
Pirx Posted November 14, 2012 Author Report Share Posted November 14, 2012 . Were these on ebay from wiktor or rotkiw ? Yes, from Wiktor There is some disturbing discoloration on that transformer, in my non-professional opinion. I would make sure that the amp is setup for the proper line voltage (assuming it's adjustable like other Stax amps) and after that get a known good set of cheap tubes to try in there. Could be that one of the 4 tubes is going bad and drawing more current than it should be. Otherwise, I don't know enough about that amp to be really helpful. There are only 2 tubes. Trafo is set to 240 V. In my opinion discoloration and temperature doesn't look good. I have schematic from SRM-006 only, but I am not sure if it is the same or similar to T1 There is no hum or noise in headphones, amplifier seems to work good. Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted November 14, 2012 Report Share Posted November 14, 2012 You need to measure the high voltage rails to know more. If they are 20% high, then what you really have is the transformer wired for 200v running on 240v. And then the transformer gets very hot. Quote Link to comment Share on other sites More sharing options...
spritzer Posted November 14, 2012 Report Share Posted November 14, 2012 That transformer should not look like that so first things first, change the tubes as they are a likely culprit. Second, check the actual socket wiring on the Stax voltage selector as it might be wrong. The SRM-006t is pretty much identical to the SRM-T1 but here is the schematic since I have it. Not the best scan but it will do. Quote Link to comment Share on other sites More sharing options...
Pirx Posted November 14, 2012 Author Report Share Posted November 14, 2012 Thank you for your interest, Kevin. You need to measure the high voltage rails to know more. After one hour of working I can read AC voltages: 251 V, 268 V and 6,25 V. If they are 20% high, then what you really have is the transformer wired for 200v running on 240v.I have no idea if it's right for T1. But I have SRM-006 schematic and there are very similar voltages: 250 V, 270 V, 6,3 V. Quote Link to comment Share on other sites More sharing options...
Pirx Posted November 14, 2012 Author Report Share Posted November 14, 2012 That transformer should not look like that so first things first, change the tubes as they are a likely culprit. Second, check the actual socket wiring on the Stax voltage selector as it might be wrong. The SRM-006t is pretty much identical to the SRM-T1 but here is the schematic since I have it. Not the best scan but it will do. Thank you Spritzer, the schematic helps a lot Voltages in my T1 are very close to those from schematic. Schematic my T1 320 V 319 V 350 V 344 V 48 V 48 V I have no idea why this trafo is so hot, everything seems to be ok Quote Link to comment Share on other sites More sharing options...
spritzer Posted November 14, 2012 Report Share Posted November 14, 2012 Too much current through the tubes would be my guess. Quote Link to comment Share on other sites More sharing options...
Pirx Posted November 14, 2012 Author Report Share Posted November 14, 2012 Too much current through the tubes would be my guess. Measurements shows about 4,5 mA/triode (probing voltage drop on anode resistors = about 150 V). But I have discovered this time there was not +320 V but only +308 V. That amp drives me crazy ;-) Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted November 15, 2012 Report Share Posted November 15, 2012 output dc on the tubes should be close to 0. 150v is not right Quote Link to comment Share on other sites More sharing options...
Pirx Posted November 15, 2012 Author Report Share Posted November 15, 2012 output dc on the tubes should be close to 0. 150v is not right Sorry, I wasn't clear. Every triode has two 33k resistors in series. 150 V is on one of them, that gives 150/33000 - more less 4,5 mA. Output is close to 0 V (flows around zero). I suspect, this is the way my amp should work. It is very strange to me but everything seems to be ok but temperature of trafo. I need to look around for another T1 and check it. Quote Link to comment Share on other sites More sharing options...
n_maher Posted November 15, 2012 Report Share Posted November 15, 2012 I wonder if some past event didn't cause damage to the trafo (before the current ownership) and it's now no longer capable of performing properly even under the best of circumstances? Quote Link to comment Share on other sites More sharing options...
Pirx Posted November 15, 2012 Author Report Share Posted November 15, 2012 I wonder if some past event didn't cause damage to the trafo (before the current ownership) and it's now no longer capable of performing properly even under the best of circumstances? Yes, it is possible. Who knows what history is behind this amp. Quote Link to comment Share on other sites More sharing options...
spritzer Posted November 15, 2012 Report Share Posted November 15, 2012 4mA seems about right but I'm with Nate here, the terminals on these transformers are open so they are easy to short. If something like that occurred then who knows what happened internally. Quote Link to comment Share on other sites More sharing options...
Pirx Posted November 16, 2012 Author Report Share Posted November 16, 2012 4mA seems about right but I'm with Nate here, the terminals on these transformers are open so they are easy to short. If something like that occurred then who knows what happened internally. True. I got this amp for two weeks. I can always replace this trafo in the future. Thank you All for help and suggestions. P.S. Perfect reason to build my own amplifier Quote Link to comment Share on other sites More sharing options...
renrossi Posted May 21, 2013 Report Share Posted May 21, 2013 Hi Everyone, My first post here and like Pirx I'm having trouble with my SRM-006tA transformer, HV rails have no voltage. According to the provided SRM-T1 schematic (it's identical to SRM-006t, right?), it looks like secondary voltages are: orange 250V, red 270V and blue 6.3V. I was wondering if somebody could please confirm the above and also the current rates, so I can replace it. Pirx, you said "I can always replace this trafo in the future.". Do you know where I could get a replacement for that? I know Stax had it customized from Bando but I guess there are other transformer models out there that could fit. Thanks in advance! Quote Link to comment Share on other sites More sharing options...
kevin gilmore Posted May 22, 2013 Report Share Posted May 22, 2013 here is the problem. everyone rates transformers in different ways, and since the power supplies in this unit are completely unregulated, and if the dc voltages go to high (more than +320/-350) parts start to blow up, there are issues. so take your best shot at what you think the under load voltages should be and hope for the best. second issue will be getting a transformer to fit in that size hole. Quote Link to comment Share on other sites More sharing options...
renrossi Posted May 23, 2013 Report Share Posted May 23, 2013 Hi Kevin, Thanks for the answer. So, am I right when I say that for SRM-006t transformer, orange is 250V, red is 270V and blue is 6.3V? And SRM-006t circuit is identical to SRM-T1? Quote Link to comment Share on other sites More sharing options...
renrossi Posted May 23, 2013 Report Share Posted May 23, 2013 Thank you for your interest, Kevin. After one hour of working I can read AC voltages: 251 V, 268 V and 6,25 V. I have no idea if it's right for T1. But I have SRM-006 schematic and there are very similar voltages: 250 V, 270 V, 6,3 V. Hi Pirx, Could you please provide a copy of your SRM-006 schematic? Thanks! Quote Link to comment Share on other sites More sharing options...
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