435 Princess amp issue

[prime]

Hi Norman, Ron, I am in the process of recapping and getting the amp going. When i first got it i noticed the main 2 amp fuse was blown, i checked under to see if maybe any wires where touching or for obvious trauma. After which i connected the power cord to my dim watt light bulb tester, after plugging in i got a very dim light for a second and then out, no short evident. I left the unit on for a while and i have noticed none of the tubes are heating up, I tested all tubes with my Heathkit 2c2, all seem ok, I disconnected the black wire from T2 amplifier to test main power cord 123 vac, i reconnected transformer and from black transformer to ground 23 vac. Not sure what this transformer should have for voltage. Also checked the inline fuse ok.  Does the amp need to be installed for proper grounding?    pete

[jukenorman]

Hi Pete,
First of all, can you change the title of this thread and your last thread - your jukebox is a 435, not a 235. That will enable others to search by model number in the future.

The amp is powered via the power supply and the tube filament voltage is supplied directly from there via a fuse. The 120VAC to the transformer for the amp DC voltages also comes via the power supply and is switched via the play control relay. It's difficult to answer your 23VAC question without knowing exactly what you are doing - if you want to test for 120VAC at the amp transformer, why don't you just measure across the two blacks? And then, all you are really testing is two fuses; it's the same 120VAC that feeds the turntable motor.

Time for you to get out the schematics and study them!

Norman.

[prime]

Hi Norman i have been following the schematics, problem is there are no voltages listed for the power or output transformer details, I do have 125vac across both blacks of the power transformer, i realize when it in the box power comes from the main power supply, i am powering up directly from a receptacle so i thought the tubes should at least glow abit.

[prime]

Hi Norman, on the schematics for the amp at caps 16 and 17 there are voltages posted, A red/wht wire 235v D red/blu 225v B blue 265v A red 310 v , should those voltages be there when amp connected to receptacle? or only when connected to power supply and record engaged? pete

[jukenorman]

Hi Pete,
You should get DC voltages there, but they will not be correct to the schematic because you won't have the filament voltage for the tubes when you are plugged into a wall receptacle. They will all be high and the lower voltages will probably be similar to the highest because you will have screwed up the current draws all over the amp.

Norman.

[prime]

Alright if i read you correctly, there is no point other than a dead short to test amp until it is in the jukebox fully functional.

[jukenorman]

You can power the amp if you wish but you either need to do it via the dedicated power supply or have a 6.3VAC supply to power the filaments of the nine tubes if you use a wall socket.

Norman.

[prime]

Thanks i will recap, confirm no short and try in jukebox thanks