diezel hagen

[pstar]

loss of volume on ch.1&2 (clean channels), ch.3&4 has plently of power but the tone is in the tiolet. Therefore noticed on back of amp a light is on indicating ch.1 &2 need to rerplace the fuse and/tubes. Got new tubes ready to do install tech notices the output transformers are reading different ohms. 1 reads 20 the other 16. Does this mean transformer is damaged ? or it does not make a difference but the tubes are the real problem? Had the power and pre. tubes test/ The 4 power tubes are all over the place , i is really bad and has a dark round mark on it, tech says no way these is going back in. Cool new tubes ready to go but the transformers has us worried, any opinions ?

[g1]

You are talking about 2 separate problems that are not related. The lights and fuses on the back are for the power tubes. They have nothing to do with the preamp channels. One of the fuses/lights is for power tubes 1&4, the other is for power tubes 2&3.
The two halves of the transformer usually read a little different so I wouldn't be too worried about the output transformer.
The loss of volume in the clean channels could be a preamp tube problem or something else in the preamp circuitry.

[pstar]

Volume loss ch1 &2.back of amp ch1&4 fuse light on indicating replacement required. Amp tech notices transformer reading 4 Pts. Different on the sides. Has concerns about transformer if damaged ? Or is the normal for these amps ? Does not want to do re biase and install new tube.
Suggestions ?

[Enzo]

16 ohms and 20 ohms is not much of a difference. Unless I see other evidence of a problem, I would not worry about that difference.

The same power tubes are in use no matter what preamp channel is selected. Fix the problem with the power amp, and I would wager that the preamp issues will disappear.


If the indicator says a fuse is blown it must be replaced. MOST of the time, a blown fuse means a power tube has failed. And that will require new power tubes.

[pstar]

My thoughts are the power tube/tubes also. Yes 1 power tube has a large burnt dark spot on it, now was this tube faulty ?
Had all tubes tested, 1 was ok, but the others were all off, (which I know power tubes do not stay matched as they put on milege ) according to the tube to the tube tester dude. Have new power tubes ready to be installed, but the tech is concern about the transformer. Now am questioning the tech's ability. If he is qualified/knowledgable , should he not be aware that the transformer sides can be different ?
Tech should install new tubes and re-biase as planned?

[g1]

Yes 1 power tube has a large burnt dark spot on it, now was this tube faulty ?

Your fuse for 1&4 was blown. Was this tube one of them? Did the tech keep track of which socket each power tube came from? At this point it seems he did not. If they all seem so different on the tester, probably best to replace all 4 anyway.

Tech should install new tubes and re-biase as planned?

Yes. And the screen resistors for each power tube should also be checked.