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Dynaco fm-1 stereo problem

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Posted on October 5, 2009 at 22:11:57
cssong@khu.ac.kr
Audiophile

Posts: 2
Location: seoul
Joined: October 2, 2009
 I recently got a Dynaco fm-1 euqipped with MPX board. Everything seems to be working fine at least superficially, but the sound does not come out in stereo. I tested every tube; all of them are OK. Any idea what's wrong? Thank you very much.

RE: Dynaco fm-1 stereo problem, posted on October 6, 2009 at 08:50:18
Bill Thomas
Industry Professional

Posts: 1330
Location: Southern USA
Joined: January 3, 2004
 Alignment of the multiplex decoder board is critical for proper stereo operation. If the transformers aren't aligned correctly, the stereo separation will completely disappear. Also, if the 6BL8 isn't lighting up, the unit will perform perfectly in Mono, but there won't be any trace of stereo. I'd start with these areas first.

Performing an alignment of the multiplex decoder board isn't very difficult. Just follow the instructions in the manual. It is always possible that a previous owner used an improper tool to try to align the transformers and has broken the coil slugs. That would also eliminate any trace of Stereo.

Do a little investigating and let us know what you find.

Hope this helps.

Bill

RE: Dynaco fm-1 stereo problem, posted on October 6, 2009 at 16:11:07
cssong@khu.ac.kr
Audiophile

Posts: 2
Location: seoul
Joined: October 2, 2009
 Thank you very much for your informative response in detail. By the way, I forgot to mention that 6BL8 lights up although two lighted bars do not meet in the middle completely. Do you know where I can find the manual for FM-1 and do I need to get a special tool or equippment to do the alignment? Thank you very much again.

RE: Dynaco fm-1 stereo problem, posted on October 7, 2009 at 20:24:31
GP49
Audiophile

Posts: 111
Location: No Cal
Joined: April 21, 2009
 The FM-1 and FMX-3 Multiplex converter manuals, including alignment instructions, are at


GP49

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