PT getting hot, need advice

[fp2000]

This is the first time I use a PT this heavy. It is a custom made heyboer with 320-0-320 secondaries 200mA, 50v bias, 6.3v 4A for heater filaments and 6.3 and 5 v for rectifiers. Two 6V6 power tubes, four 12AX7, and transformer driven reverb that needs some tweaking.

After playing for about 20 minutes I noticed that the PT was fairly hot, hot enough for not being able to put my hand on it for more than maybe 2 seconds.
The amp is setup on a very tiny head cabinet that looks like a mini fender amp head. The PT and OT barely fit height wise. Not to mention that one of the 6V6 power tubes is about half a inch away from the PT and I had a back panel that was covering all of the PT but leaving the tubes enough space to breathe.

The question is, is this something normal? should I be concerned about it?
Even if the amp has enough air circulation, how hot does the PT get?
From now on I am just going to keep the back panel off, everything is so cramped inside. I can post some pictures later so everybody can see what I mean.
I appreciate any replies
Thanks

Frank

[Chris333]

I have a couple amps that have PTs with around the same specs (or lower) that run two 6V6s, and they get warm, but never hot to the touch. I'm assuming you don't have the power tubes biased way, plate-melting hot... Any chance it's drawing current someplace it shouldn't? If you can measure current going into the PT, then you'll know if it's drawing more than you're expecting it to. If it gets hot right away, it might be worth some investigation, but if it takes 20 minutes of playing cranked to get hot, maybe it just needs a little more air...

[heisthl]

Warm up the amp and be ready with a amp meter and clip leads, turn off the power and the standby, clip your meter to the legs of the standby switch - leave the switch off but turn the power switch on. After a few seconds you should be getting an accurate current reading. If its over 150MA you have a definite problem. I would expect to see les than 100 at idle. You may have to repeat this test by putting the meter in series with the 6v heater, and if good, the 5v rectifier taps (tap readings needed only if the main secondary reading is good). How bright does it light the light bulb test fixture at idle?

[fp2000]

The tubes are biased at about 22mA, and the pilot light is just bright enough like I would expect, not overly bright. I will try measuring the ac amperes going into the primaries and the each individual secondary just to make sure that something is not shorting.
Thanks for the ideas

[heisthl]

I didn't mean the pilot light, what I meant is you use a standard 100 watt bulb in series with the hot lead of an extension cord and plug your amp into the extension cord, how bright does it light the lightbulb.

[Funkalicousgroove]

If there is a huge current draw I should think it would blow the fuse (Unless it's mis-wired or too big)

Can you post a pic or two Inside and out, could be something simple.



Could be a bad transformer

[fp2000]

Funk, you freaked me out when you said "bad transformer", it wasn't though.
It happens to be that the cabinet is rather small and it didn't allow for much ventilation, also I had a back panel put on.
I took the chassis out and played for about 15 min and the transformer was just a little warm so the issue is most likely the back panel, added to the already small cab.
For now on I will just leave it open in the back to allow for proper ventilation.
Also, by following Heisthl's recommendations, I did measure the current on the PT. About 58mA on idle, and when maxing out all the volume controls it pulls 180mA at some points, depending on the playing. My PT is rated for 200mA, so I don't worry much about that, not to mention that I would never play the amp with all the controls up in a real life situation, but it gave me peace of mind.
Here are some pics. I will probably post all the pictures on a separate Post, along with some clips, if I find a good mic. I've never recorded.
Thanks all you experts for your thoughts, they are very much appreciated.
Frank

[Funkalicousgroove]

Perhaps a small fan inside that cab would help your heat issue?

Looks really cool BTW, is she a screamer??