5e3s run "hot"?

[super&plexi]

Was just recording with my 5e3 tweed 'clone'... when it was built all the voltages seemed pretty correct it's one of the higher voltage mojotone OT's.       I've always just taking it to play around with so I ran a fan on it all the time since it was built.


It's got the protection diodes in it on the rectifier...     I've run a gz34 in there and I didn't think it was too hot but then again I had the fan on it always.


One other consideration before I tear into it and take voltages and double check on that Transformer is I just noticed I'm running an old Coke bottle type 5u4 cuz I remembered that I saw the brand new rectifier I had installed give a flash I'm pretty sure it was a sovtek that I got years ago from Musicians Friend Butthead got into it years after I should have checked it out right away but I think I remember Ed Chambley saying the same thing...             if it wasn't sovtek and Musician's Friend I'll print a retraction but I really am about 99% in those 2 .....       


I'm just thinking maybe they run hot because the tranny is right there radiating it's Heat with the rectifier and power tubes underneath all in the same place right next to the jewel which I don't really know if it puts out too much heat...   on a question like this should I just post voltages and parts I used that may have been different than exact original schematic

[dunner84]

Mine runs pretty warm. It is biased around 98%. it drifts a bit, but it is always around there. A 5u4 draws an extra amp of current than a 5y3, so that will contribute more heat to the amp for sure. Crack it open and take some voltage readings.

[HotBluePlates]

... I'm just thinking maybe they run hot because ...

Was there something that happened that made you suspect a problem with the amp?

I mean, you could open it up just because.  Or you could just play it...

[super&plexi]

Days before this I had run through a chart with all the rectifier voltage drops and current pull. I thought my memory was good enough... I thought the 5u4  was on par.... sure another amp and no fan that would definitely do it.  Since my computer broke and I'm on these darn tiny phones and pitifully slow tablet really frustrating because I print out everything. 


 back in storage I have tons of books filled with all the info and charts I need.      maybe I should just get one book on increasing your memory or eat more fish..          when summer comes around will get the boat up and definitely fish more it's just too cold now.        I'm already onto my 76_78 ul pro R.     I was recording the Tweed because it's up for sale and I wanted to make sure it was cool (figuritively).


   I do remember seeing 25 volts off  pin 8 rect. B+ , pin 8 to chassis.  That weird?.   I'm going to go right now trade a few rectifiers and post the voltages in a few minutes.   


Thanks for you guys input

[super&plexi]

Okay right off the bat I got 121 coming out of thewall I'm used to about 1:17.... but that's not a big deal the thing I'm noticing is my variac well it usually runs a good deal under whatever the wall is you know compared to what it says on the dial at 1:10 creeping to 1:15 I was already past 1:25....


The knob hasn't slipped at  all it's exactly from 0 to 130..... before I go on with this should I repost a different thread asking if Variac's drift?     And yes I know I should check voltages and not assume.  And yes I do feel like an ass....

[super&plexi]

Guess I need to change out filter caps too. Now I remember lowering to 2_33 in series instead of 47uf__ hated it.  Now measures (I know meter not perfect, but 3 different say bout same at least) 19, 24, 10 at 700, 500, 500, a, b, c. Kr-270 ohm measured 284.4.


Got 100 x 100 on Kr, should change, or maybe even should have changed that first before the filter caps.  The one I've always wanted this dirtier,  but it just barks like a jtm45.

[super&plexi]

117.5 wall ac gets 391 b+ . 6.4V. heaters ac.    23.73V.Kr


350.8DC cathode C&R to pin "brn"(ot) right 6v6.... 348.3 left 6v6 pin "blue" (ot) .        50V across both red leads.... that represent the voltage drop of the recto tube. The 391-350.8....nope 'scatch head'.


While doing this I pulled the lamp over to illuminate the amp for a picture and in doing so knocked one of my prized wixt svteks off the card table onto the variac on the floor close to a two foot fall onto the metal frame of the variac.  as far as I can see it didn't break although as soon as I get into my Pro I'll be looking for white gas right off the bat I sure hope not as they are the only 6l6  that can handle the UL Pro Reverb's way high plate voltage.

[super&plexi]

Jeez wots upp? DAT dern meeter jus sez too double naughts....0000


.Har har. I promise I have not had one drink today.....Or tonight.

[HotBluePlates]

... Kr-270 ohm measured 284.4. ...

23.73V.Kr

350.8 ... right 6v6.... 348.3 left 6v6 ...

You're killing me, Smalls...  Way too much info & no units.

23.7v across the cathode resistor measured at 284Ω.  (23.7v/284Ω) / 2 = ~42mA

350v or 370v plate-to-cathode.  370v * 42mA = 15.5w.  Not far off, even using worst-case rounding everywhere, including not subtracting screen current out of the cathode current number.

Could just be a pair of tubes that run hot.  Or you could choose to use a 300Ω cathode resistor.  Your call.

[p2pAmps]

... Kr-270 ohm measured 284.4. ...

23.73V.Kr

350.8 ... right 6v6.... 348.3 left 6v6 ...

You're killing me, Smalls...  Way too much info & no units.

23.7v across the cathode resistor measured at 284Ω.  (23.7v/284Ω) / 2 = ~42mA

350v or 370v plate-to-cathode.  370v * 42mA = 15.5w.  Not far off, even using worst-case rounding everywhere, including not subtracting screen current out of the cathode current number.

Could just be a pair of tubes that run hot.  Or you could choose to use a 300Ω cathode resistor.  Your call.

I used a 330Ω cathode resistor in mine and it was perfect

[super&plexi]

Thank u all for input.... P2p if I may ask value of person tubes Kr Ive got 100uf....think it's too big probably go 25 if can find in bins.  Want more grit.  12ax in p1 doesn't do.  Ts9., clones,  od1 all cool,  just wanted to see if "grind" like I've heard some -even my 18 stout reverb original ground down (snarled dirty)  more than this


Maybe just addition of 2nd spkr. (wasn't afraid of blowing stout).... Oh crap,  just thought......  0.1 caps..... Too full signal hitting pwr.  & pi. ?  Turning out/into too much for anything being sold/maybe.


Easier to start again-thisvis almost pristine.