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Dynakit ST 70. A Restoration Journey

Crap! It happened again!
IMG_1554.jpeg
This time it was the right channel. The EL 34 shorted and took out the grid screen resistor. Just like the last time. At least that’s what I hope happened. Must have gotten a couple bad tubes in the quad I bought. This time it also affected the 15.6 ohm resistor that’s on the socket of the tube that didn’t short. Don’t know what’s up with that but if anyone has any ideas I’m all ears!

Off to the parts store. Mark
 
Stereodiver said:
Crap! It happened again!
View attachment 3473873
This time it was the right channel. The EL 34 shorted and took out the grid screen resistor. Just like the last time. At least that’s what I hope happened. Must have gotten a couple bad tubes in the quad I bought. This time it also affected the 15.6 ohm resistor that’s on the socket of the tube that didn’t short. Don’t know what’s up with that but if anyone has any ideas I’m all ears!

Off to the parts store. Mark
Click to expand...
What EL34 tubes are you using?

Thanks!
 
It was a 100 ohm 1/2 watt PRP metal film. I had 1/4 watt resistors on each tube when it happened the first time. And the recomendation from some folks here was to up it to 1/2 watt.
 
Just poked around a little and it seems Dynakit Parts is the only place to get the 15.6 resistors. Anyone got any other places I could check?
 
The 15.6 is shared so not terribly surprised

You can use other more common values, just set it to a different voltage. Total current is 100ma per channel, a 15 ohm resistor with bias set to 1.5 volts will work exactly the same. Can also make a resistor out of series or parallel mixes if needed but I'd probably just stick a 15 in there and make a note of the change.
 
@Lavane No I did not buy them on eBay. I’m not going to name the seller because it isn’t their fault I had two of a quad go bad. If it happens a third time I will certainly look into a different brand.

@gadget73 Thanks buddy. I do understand what you’re saying but I’ll prolly just order the same one to eliminate any confusion if at some point in time I opt to move this amp along.
 
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