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Post by smokeycigar on Nov 3, 2013 2:53:14 GMT
Update, Silly me didn't correctly wire the plug to my PS. Today wired it correctly. And..... She powers up!!! Tested her with an input and headphones... perfect. good to go!!! Now if only Perreaux will sell me a replacement tranny, It will be simple conclusion.
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Post by smokeycigar on Nov 3, 2013 2:56:56 GMT
I think we have already established that there is an internal short circuit in the transformer between the screen and the secondary windings. After removing the tranny from the PCB. The secondaries do not have continuity with the screen. It seems that resistor next to the smoothing caps is connected through the black jumper to earth. On the other hand the two primaries both show continuity with each other. All 4 connectors show continuity. So it was both primaries that were shorted, secondaries and screen had no issues.
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Post by smokeycigar on Nov 3, 2013 2:59:56 GMT
The large resistor looks more like a 0.47ohm by my reckoning! (yellow, violet, silver, silver) That's what I concluded also. It's connected to the center tap (0v) after the smoothing caps. Do you know the purpose of this part of the circuit?
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Post by Deleted on Nov 3, 2013 3:49:04 GMT
Good luck ! There doesn't appear to be anything else available with that small a diameter.
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Post by smokeycigar on Nov 3, 2013 5:56:12 GMT
sandyk said: Good luck ! There doesn't appear to be anything else available with that small a diameter. Thanks, I'll need it. Worst come to worst, I'll build another external PSU.
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Post by Deleted on Nov 3, 2013 6:20:11 GMT
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Post by smokeycigar on Nov 3, 2013 7:44:41 GMT
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Post by Deleted on Nov 3, 2013 8:09:20 GMT
smokeycigar I am using an inexpensive Altronics H0480F case to house 2 x Altronics 18-0-18 30VA transformers (M4918A) for the Class A HA/preamp as in the RG thread. It's certainly not a large case, and ABS cases are quite suitable for external PSUs using toroidal transformers. These transformers have an epoxy centre for the mounting bolt. I mount mine on a standard small blank copper PCB using stand offs to give clearance underneath for additional airflow. Using a standard sized blank PCB is far less fiddly than cutting a suitably sized piece of aluminium like I did previously. ! I fit a 3mm screw with a solder lug to the PCB to permit connecting IEC earth from the mains socket to the copper underneath for extra protection. Mine uses 2 x 3pin XLR sockets for the AC supplies (dual mono) , a fused IEC socket and a toggle switch. Regards Alex www.altronics.com.au/index.asp?area=item&id=H0480F
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Post by Deleted on Nov 3, 2013 12:18:29 GMT
Update, Silly me didn't correctly wire the plug to my PS. Today wired it correctly. And..... She powers up!!! Tested her with an input and headphones... perfect. good to go!!! Well done! It's great when you suss it in the end, isn't it.
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Post by smokeycigar on Nov 3, 2013 13:52:49 GMT
Thanks, Reminds me of coding, except you need to 'physically" troubleshoot Now to source an appropriate tranny...
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Post by smokeycigar on Nov 4, 2013 11:14:10 GMT
SO if the amp functions, I decided to conduct some quality tests. BIG DISAPPOINTMENT. It sound horrible!!! Sounds like the battery is running out. low levels it sounds ok. At normal volumes SUPER distortion. When bass kicks in it just distorts like crazy. Back to diagnosis, lets check those connections the the PS again.
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Post by Deleted on Nov 4, 2013 11:41:31 GMT
smokeycigar I can't imagine that it was like this originally, so there is likely to be other damage caused by the transformer break down. Unless you are able to post a copy of the schematic, it is going to be hard to assist you with further fault finding,other than to check that you have supply rails of most likely around + and -16.5V with a 12-0-12VAC supply. Regards Alex
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Post by smokeycigar on Nov 4, 2013 11:54:19 GMT
Checked the rails and only got about 6Volts each. One on the secondaries was not hooked up. Fixed and now she it thumping again.
Contacted Perreaux, and they advised they don't have any spare trannies in stock.
Looked for custom trannies that would fit (including static screen), will cost $75. I think not. Looks like I have to play Tetris inside the case with a standard tranny (should be around $20-25)
Compared to the recently modified X-can V3 it sounds flat, but perreaux SXH2 a known for their clinical and accurate reproduction. (from what I remember)
Still sounds great though.. Will let her warm up.
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Post by Deleted on Nov 4, 2013 12:15:02 GMT
Checked the rails and only got about 6Volts each. One on the secondaries was not hooked up. Fixed and now she it thumping again. Contacted Perreaux, and they advised they don't have any spare trannies in stock. Looked for custom trannies that would fit (including static screen), will cost $75. I think not. Looks like I have to play Tetris inside the case with a standard tranny (should be around $20-25) Compared to the recently modified X-can V3 it sounds flat, but perreaux SXH2 a known for their clinical and accurate reproduction. (from what I remember) Still sounds great though.. Will let her warm up. That's good news ! I look forward to seeing how you overcome your transformer problem.
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Post by Deleted on Nov 4, 2013 13:05:45 GMT
As you're in Aus why not make your own external psu like Alex inferred earlier? Jaycar or Altronics parts or maybe a kit. You should get a small increase in sound quality. Failing that you may find a cheap one of Mike's "Little Pinkie" psu's going cheap on an auction site or forum. Get the one meant for X-Series V3 or 8 which has the 12-0-12vac output you require. e.g. one for sale in UK Ebay UK, you might find one in Aus too.
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Post by smokeycigar on Mar 27, 2014 0:09:19 GMT
Hi all, This has been on the back burner. I couldn't find an appropriate and financially feasible transformer. Until now.. This isolation transformed has 2 * 12v 5va secondaries. It's an IE tranny and only costs $6. So for shits and giggles I purchased one, and will install it. Just fits in the case, but since it's encapsulated, it should be fine.
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Post by smokeycigar on Mar 27, 2014 8:13:25 GMT
Installed the tranny, she powers up, and first impressions she sounds great!! No compression or indicators the tranny can't provide enough juice. Running it in to make sure it's stable.
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Post by Deleted on Mar 27, 2014 9:14:58 GMT
Looking good ! Are you using the recommended fuse rating too ?
Regards Alex
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Post by smokeycigar on Mar 27, 2014 22:47:10 GMT
sandyk,
Didn't have a fuse close to 63ma, just used the one that was in there before. Either a 250 or 500ma
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Post by Deleted on Mar 27, 2014 23:16:45 GMT
sandyk, Didn't have a fuse close to 63ma, just used the one that was in there before. Either a 250 or 500ma It would be a good idea to replace that with a 100mA Quick Blow fuse.
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Post by smokeycigar on Mar 27, 2014 23:58:42 GMT
Agree, need to get a hold of a few.
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Post by Deleted on Mar 28, 2014 0:19:26 GMT
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Post by smokeycigar on Mar 28, 2014 4:13:39 GMT
Sounds like a plan, I'll look into it. I believe the original one from perreaux was a 250ma, which is high for the original 10VA unit. Might be the reason it was failing.
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Post by Deleted on Mar 28, 2014 4:49:55 GMT
Sounds like a plan, I'll look into it. I believe the original one from perreaux was a 250ma, which is high for the original 10VA unit. Might be the reason it was failing. The correct type and value of the fuse may have protected the transformer in the event of a fault condition in the amplifier, but high mains voltage surges could have resulted in transformers breaking down.
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Post by smokeycigar on Mar 28, 2014 5:07:17 GMT
When my two different units failed they both happened overnight while they system was on (cd player/ amp) with no signal. Basically woke up in the morning with the LED off, and amp non functional.
One outliner cause I though of was related to the ground from the phone jack coupling to the earth on the chassis. That is, the headphone plug is in contact with the case. While using the second amp, I place a piece of paper between the jack and the case and had no issues. A while later, I ditched the paper, and alas the transformer got fried. No idea if this is the reason, but I tough some sort of loop occurred overloading the tranny.
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