New to forum and hobby - resources?

[vintagekiki]

BTW, a 5V winding for a tube rectifier can never be a part/tap of the 6.3V heater supply.

The winding for heat tube rectifier 5 or 6.3V at the classictone 40-18035 transformer is intended for directly heated tube 5U4; GZ34 (5 VAC) or for indirectly heated tube EZ81 (6.3 VAC)
If EZ81 is used, winding 6.3V can be used for other tubes, because + HV at indirectly heated tube is obtained from the cathode.

[jy999]

Yup, shorted transformer primary. Setting up the tranny on the bench lit up my light bulb limiter super bright, with no voltage being read across the secondaries at all. I just ordered a new hammond to replace it.

[jy999]

Hey everyone!

New transformer came. Hammond 290 PAZ. Got it on my bench to test everything. I double and triple checked everything. Put marr connectors on all primary and secondaries for safety, to isolate them, and hooked it up.

I'm a little confused by what I found, so I thought I'd ask experienced people here to see what's up.
I'm in Canada, and my line voltage according to my Fluke meter is 121v
- I hooked the primaries up to the neutral and hot lines for the 120v winding
- all my secondaries gave me higher voltages than expected. the 290v-290v HT rail (580v), gave me 620v.
- from my understanding, the voltage won't drop under load.. or will it? am I missing something obvious?

I wasn't using my variac to test, but I did have it connected to my bulb limiter. I didn't check the resistance of the bulb, but with very low / no current flowing (transformer loss? not sure) I assumed the voltage drop across the bulb would be minimal. Also, that wouldn't explain /higher/ voltages.

Thoughts? Is this within expected tolerances? I'm thinking of emailing them, but being a newbie, decided to check in first.

[Enzo]

The spec output voltage is what the transformer provides at full current load. It is normal for transformers to run high unloaded.

Ever sit in a room with the lights on and some heavy draw turns on, like air conditioning or the furnace, and your light get a little dimmer? Or sit in your car idling, then turn on the AC and the car motor slows down some? Same deal.

Got any wall wart power adaptors? Check the voltage on a "9v" one and see it is more likely 12-14v. It will only be 9v at the rated full current.

[jy999]

Thanks for the reassurance. In thinking about it I suppose it's just ohms law. The voltage drop in the internal impedance is proportional to the current flowing in it. I should measure the winding resistance and see how close I can predict it and expected curry load.

[jy999]

Hey everyone,
I just want to say thank you for all the help. I installed the new transformer, and apart from a few hiccups (not quite the same size, short wires, etc etc.), I got it all mounted and wired up satisfactorily.

Started it up with limiter and variac. no problems! It worked first try, driving an old 8 ohm Line 6 cab I have. Fantastic little amp, big upgrade for me!

All done safely, another amp saved and repaired!

[bsco]

http://guitar-gear.ru/forum/index.php?app=core&module=attach&section=attach&attach_i d=14475
The Electric Guitar Amplifier Handbook - Jack Darr

I have that book. it is a very good book......