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The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Tubes4hifi VTA tube amp and preamp kits and all Dynakitparts.com products


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    No sound from system

    Dusterdave
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    Dusterdave


    Posts : 8
    Join date : 2017-04-09
    • Post n°1

    No sound from system Empty No sound from system

    Post by Dusterdave Tue Sep 19, 2023 11:07 am

    Hi everyone,
    Ok here’s my problem.  The other day I was setting up a new turntable. When I turned everything on there was a ground hum.  I soon discovered one of the ground wires on the phono preamplifier had detached.  I reattached the wire and turned the system back on. Great, no hum!  Then I noticed there was no sound from the right channel, hmmmm.  Shut the system off checked everything and turned everything back on.  Nothing!  Everything turns on, the M125s, preamplifier, phono preamplifier seem ok. I have ruled out the turntable,phono preamplifier, and speakers as I hooked them up to a receiver. Also, still no sound with dvd or tuner.  That pretty much leaves the preamplifier or M125s I think.  Any help would be appreciated.
    Thanks Dave
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    Bob Latino
    Bob Latino
    Bob Latino
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    Join date : 2008-11-26
    Location : Massachusetts
    • Post n°2

    No sound from system Empty Re: No sound from system

    Post by Bob Latino Tue Sep 19, 2023 4:16 pm

    Dusterdave wrote:Hi everyone,
    Ok here’s my problem.  The other day I was setting up a new turntable. When I turned everything on there was a ground hum.  I soon discovered one of the ground wires on the phono preamplifier had detached.  I reattached the wire and turned the system back on. Great, no hum!  Then I noticed there was no sound from the right channel, hmmmm.  Shut the system off checked everything and turned everything back on.  Nothing!  Everything turns on, the M125s, preamplifier, phono preamplifier seem ok. I have ruled out the turntable,phono preamplifier, and speakers as I hooked them up to a receiver. Also, still no sound with dvd or tuner.  That pretty much leaves the preamplifier or M125s I think.  Any help would be appreciated.
    Thanks Dave

    The most common cause of no sound from one of your VTA M-125's is a bad rectifier tube. Check to see if you can get any bias voltage on that amp that is not working. If you get no sound and also no bias voltage the problem is almost always a bad rectifier tube. NOTE > Just because a rectifier "lights up and stays lit" is no guarantee that the rectifier is working properly.

    Put in a new rectifier tube and check for bias voltage after about 30 seconds. If you get bias voltage the amp should work OK now.

    Bob
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    Dusterdave
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    Dusterdave


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    • Post n°3

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    Post by Dusterdave Tue Sep 19, 2023 5:33 pm

    Hey Bob,
    It is so good to hear from you! I picked up my ST120 at your place and a few years later I picked up my M125s from you. Are you still in Sturbridge? I have really enjoyed my equipment from you and Ray.

    I will make an SS rectifier as per a post on this site and try that. Any thoughts on why the rectifiers blew because of a faulty ground?

    Thanks again Bob!
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    Bob Latino
    Bob Latino
    Bob Latino
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    • Post n°4

    No sound from system Empty Re: No sound from system

    Post by Bob Latino Tue Sep 19, 2023 6:41 pm

    Dusterdave wrote:Hey Bob,
    It is so good to hear from you!  I picked up my ST120 at your place and a few years later I picked up my M125s from you.  Are you still in Sturbridge?  I have really enjoyed my equipment from you and Ray.

    I will make an SS rectifier as per a post on this site and try that.  Any thoughts on why the rectifiers blew because of a faulty ground?

    Thanks again Bob!

    Hi Dave,

    Yes > The rectifier could have gone out because of a faulty ground ? The underlying problem is that years ago all the tubes were made in the USA, Great Britain and Germany. Nowadays the tubes are made in China, Russia and the Slovak Republic. Many of the newer tubes are made with cheaper alloys inside and they don't test them as thoroughly as they use to "back in the day". The result is shorter tube life. This is something all of us that still use tubes has to deal with every day.

    Bob
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    Dusterdave
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    Dusterdave


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    • Post n°5

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    Post by Dusterdave Tue Sep 19, 2023 8:08 pm

    Thanks again Bob. I’ll find some 1N4007s and try it!
    Now I’m thinking of “stocking up “ on some tubes. It will be interesting to see if someone starts making quality tubes in the future. With vinyl and good stereo equipment becoming popular now…..maybe.
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    Dusterdave
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    Dusterdave


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    • Post n°6

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    Post by Dusterdave Mon Oct 02, 2023 11:49 am

    That was the problem. That surge blew both rectifiers. I built the homemade SS rectifiers that Bob outlined. They work great and are an inexpensive way of testing or for use. MUCH less expensive than replacing a blown tube rectifier!

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    • Post n°7

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