RE: Dynaco A470 Output Transformers

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Posted by strijw426 (A) on August 18, 2014 at 03:46:40

In Reply to: Dynaco A470 Output Transformers posted by strijw426 on August 17, 2014 at 04:11:26:

Thanks to everyone for their suggestions. I may join the DIY Tube and SET groups to get their expertise too.

Based on remarks here and on DIY Tubes I suspect that the one transformer I removed that had the lowest readings is the one that is defective, likely with some shorted turns. That was my original suspicion all along. As mentioned by one response above, transformers that develop shorted turns usually go down in resistance, not up. The one I opened up had some evidence of black carbon deposited on the outer wrap of the windings.

Joe Curcio recommended that I test the unit with a known signal level and listen to see if one channel is noticeably lower than the other in sound level. I could also measure the output level with the AC volt scales of my VTVM or VOM at 1kHz while the outputs feed fixed 1% load resistors. I have two 100 watt 8 ohm non-inductive load resistors I can use for the test. I have an audio signal generator that I can use to supply a monitored and fixed output to connect to the input of both channels of the power amplifier at the same time.

If I eventually go the route of replacing the chassis metal with stainless steel, I will go with a star grounding system to help minimize problems with hum. I have read comments about the new kits available from Tubes4HiFi and Dyna Doctor and am still digesting all the information.

Although it would be nice to have both output transformers look like the originals, I really want the unit to sound its best over cosmetic concerns.

Joe

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Follow Ups Full Thread

Topic - Dynaco A470 Output Transformers - strijw426 04:11:26 08/17/14 (13)

RE: Dynaco A470 Output Transformers - strijw426 03:46:40 08/18/14 (0)

RE: Dynaco A470 Output Transformers - Frihed89 23:59:35 08/17/14 (0)

RE: Dynaco A470 Output Transformers - mark.korda@myfairpoint.net 10:58:45 08/17/14 (9)

RE: Dynaco A470 Output Transformers - strijw426 12:16:58 08/17/14 (8)

RE: Dynaco A470 Output Transformers - strijw426 12:08:17 08/20/14 (0)

RE: Dynaco A470 Output Transformers - Tre' 16:40:53 08/17/14 (0)

RE: Dynaco A470 Output Transformers - strijw426 14:36:43 08/17/14 (3)

RE: Dynaco A470 Output Transformers - Caucasian Blackplate 18:42:03 08/17/14 (0)

RE: Dynaco A470 Output Transformers - unclestu 16:46:45 08/17/14 (1)

RE: Dynaco A470 Output Transformers - strijw426 18:27:07 08/17/14 (0)

RE: Dynaco A470 Output Transformers - unclestu 13:07:00 08/17/14 (1)

RE: Dynaco A470 Output Transformers - mark.korda@myfairpoint.net 13:28:36 08/17/14 (0)

RE: Dynaco A470 Output Transformers - Cougar 07:48:53 08/17/14 (0)

Follow Ups

RE: Dynaco A470 Output Transformers - strijw426 03:46:40 08/18/14 (0)

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