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Dynaco Mark VI Help

A

ampsandsound

Active Member
Hey guess. I traided my ST70 and some cash for 2 Dynaco Mark VIs.

Here is the problem. The 4ohm tap is non working on one.
The 2nd amp seems fine.

(Both amps look unmolested, origonal condition.)
If I add vol. I can faintly hear sound form the speaker... WTF?

Please someone tell me... is this serious? Whats wrong?

Thanx,

Justin:tears:
 
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Could be a bad or open winding on the 4 ohm side of the output transformer, but you really don't want to hear that as the output transformer may need to be replaced in order for both taps to work properly.

To find out for sure, take some continuity measurements with an ohm meter between the 4 & 8 ohm taps. Also look to see that the wire is not corroded connecting to the 4 ohm terminal.
 
what would those results look like. I am returning to seller to have inspected by his tech.

Im not really able to make mesurments myself.
 
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justinsweber said:
what would those results look like. I am returning to seller to have inspected by his tech.

Im not really able to make mesurments myself.
Click to expand...

A digital multimeter is available a Radio Shack for between 20 and 30 dollars. Set the dial for the lowest value of resistance (see the document that comes with the meter for that setting.) Turn off the amp, unplug it, disconnect the speakers. Place the black probe on the common terminal of the bad channel, place the red lead on the 4 ohm terminal. Read and jot down the result. Do the same for the 8 ohm terminal. Now do the same tests (under the same conditions) to the working channel. Compare the readings of the two channels. If they are different then you have an issue. If the seller is willing to make good on the amp do that. Otherwise post back we can try to help you with it.

Best of Luck on this.

Shelly_D
 
Just look at the connection to the terminal strip. Is the wire correctly soldered to the connection?
 
justinsweber said:
seems to be open. the seller is allowing me to return.
Click to expand...

If it looks like it is open visually and the seller will repair for you then defiantly go that route. Get the guy that took you money to make good, especially if he has a tech that can do the work. If you don't have experience mucking around inside a tube amp (I'm guessing you don't but please forgive me if that assumption is incorrect) then get it fixed by the seller.

Shelly_D
 
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