Power transformer insulation breakdown. Both are shorted between the two HV windings... We're working out whether to repair, or rebuild into something better
Roscoe
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| Antique Sound Labs Monoblocks stopped working http://dcaudiodiy.com/phpBB3/viewtopic.php?f=5&t=92 |
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| Author: | TubeDriver [ August 2nd, 2013, 7:14 pm ] |
| Post subject: | Re: Antique Sound Labs Monoblocks stopped working |
bigthinker wrote: I appreciate all the response to this post. I do not have a lot of experience but I do own an Ohm meter, so I can respond to some of your recommendations. I was thinking it was the mains transformer. If someone knows of a reputable place to get them repaired or knows for certain how to repair this, please let me know. Again, thanks for all the positive suggestions and thoughts on this problem. If, and I repeat if it is the PT, you should just get replacement PT. but two separate PT don't just fail unless you had a lightning strike or something like that. |
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| Author: | Don Diego [ August 2nd, 2013, 7:16 pm ] |
| Post subject: | Re: Antique Sound Labs Monoblocks stopped working |
ASL is the poster boy for what's wrong with Chinese electronic gear. They sound great and are affordable but construction, variability between units and reliability leave a lot to be desired. It's a quick search on the web to find a host of problems with ASL amps from respected audio reviewers to end users. I would love to hear your amps once you get them fixed. Good luck. |
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| Author: | Roscoe Primrose [ August 12th, 2013, 9:53 am ] |
| Post subject: | Re: Antique Sound Labs Monoblocks stopped working |
I've got the ASL amps at this point. 845 supply HV rectifiers in one amp, driver supply HV rectifiers in the other... Sure looks like a power hit at this point... Plan is to replace the rectifiers for both supplies in both amps, when we should be as good as (or better) than new. Will keep you updated. Roscoe |
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| Author: | Guy [ August 23rd, 2013, 10:43 am ] |
| Post subject: | Re: Antique Sound Labs Monoblocks stopped working |
BigThinker, Did you get resolution to your problem yet? I haven't seen anything new in a while. |
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| Author: | Roscoe Primrose [ August 23rd, 2013, 1:35 pm ] |
| Post subject: | Re: Antique Sound Labs Monoblocks stopped working |
Power transformer insulation breakdown. Both are shorted between the two HV windings... We're working out whether to repair, or rebuild into something better Roscoe |
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| Author: | Guy [ August 24th, 2013, 10:11 am ] |
| Post subject: | Re: Antique Sound Labs Monoblocks stopped working |
How did you figure that out? Did you open up the transformers once you found they weren't working? |
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| Author: | Roscoe Primrose [ August 24th, 2013, 10:25 am ] |
| Post subject: | Re: Antique Sound Labs Monoblocks stopped working |
Guy wrote: How did you figure that out? Did you open up the transformers once you found they weren't working? With a multimeter. Only about 150ohms between the two primaries... 
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| Author: | Guy [ August 25th, 2013, 4:19 pm ] |
| Post subject: | Re: Antique Sound Labs Monoblocks stopped working |
Got it - Grrrracias! 
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| Author: | rock4016 [ September 5th, 2013, 7:56 am ] |
| Post subject: | Re: Antique Sound Labs Monoblocks stopped working |
I'm confused , you meant there's 150 ohms between the secondaries? If that's the case, what would you expect to see? Or are you saying you have a primary to secondary short?For example I just built an SE amp that has an unloaded B+ of about 490V. I measured 75 ohms between the secondaries when testing the power transformer that I used. |
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| Author: | Roscoe Primrose [ September 5th, 2013, 8:58 am ] |
| Post subject: | Re: Antique Sound Labs Monoblocks stopped working |
rock4016 wrote: I'm confused , you meant there's 150 ohms between the secondaries? If that's the case, what would you expect to see? Or are you saying you have a primary to secondary short?For example I just built an SE amp that has an unloaded B+ of about 490V. I measured 75 ohms between the secondaries when testing the power transformer that I used. If you've got less than an infinite resistance between two different secondaries (assuming they're note connected to anything else) you've got a problem. These transformers have low resistance between two different HV secondaries.... Roscoe |
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