Solid State Guitar Amp Forum | DIY Guitar Amplifiers

i pulled all the ic's and still no +15v.all were in sockets thank god!i found a solder bridge between a black ground wire and the positve of the circuit. it has been corrected.the big short is gone,but apparently i still have one to find. i found 2 capacitors with bad solder joints and fixed them with buss wire as i think the trace was loose or missing(coudln't solder,so i followed the trace to the next component and buss wired the lead to the next component).all fixed now!i took the preamp board outside to get really good look in  natural light and looked it over with a fine tooth comb.i found a solder bridge on the one board and opened it up hoping that was my short to no avail.when i turn the unit on the +15v reads 11vdc then diminishes to 3vdc.still something drawing voltage from my supply.when turning the amp on there is a loud squeal.when we hooked a guitar to the input it had a loud guitar sound and squeal for about 4 seconds then nothing no squeal due to lowered voltage.....ed

thanks Dr Gonz for posting schematics.all diodes on the board with the 15v supply regulators test good with a diode test. both 24v supply rails are present.when i do the pinkie test on the regulators.the new regulator i installed is getting hot to the touch.something must be loading it down.getting .003v output from it.now how to find the shorted part that is doing this?i have tested all the capacitors with a capacitor meter and also checked across the leads of the caps on low ohms of my fluke for shorts and i haven't found anything.also tested a transitor on the board and it is good also.there is a trace cut near a opto- isolator.i believe it was done at the factory and it doesn't seem to be in the same part of the circuit as my problem.as the amp previously did work with this same condition.just didn't seem to have 130watts.previously i found 2 wires detached from the unit.a black wire on the regulator board and a purple wire in the reverb board. they have been repaired.that is all i have for now. open for any ideas for testing for the short.guess it could be on any of the board with the 15+v supply.thats alot of parts to check.might not be on the supply board ,but may be on another board in a later part of the circuit.tough to test do to layout of boards all sandwiched together vertically.

i am supposed to get a schematic from polytone from Diane. it is supposed to be in the mail.i tried the effects loop with my traynor 20 watt tube amp and got very low volume using the traynor as a preamp and the polytone as a power amp and also got low volume with the polytone as a preamp and the traynor as a power amp.the only thing i question is that the polytone has what is called a main out.is it a preamp out,speaker out,power amp out.need a manual that identifies what it is.maybe thats why i didn't get volume using the polytone as a power amp.as i hooked the traynor send  into the effects return of the polytone.i don't have the volume i had previously.i am guessing i might of not hooked up a connector before putting the two back boards on the amp again. i thought i plugged everthing in ,but now i/m not sure.i've lost my patience with this thing and i am going to wait till i get the schematic to renew my interest in this thing...Ed!!

hey gang! i had a heck of a time getting the alligator clips on to the emitter of the transistors.i got +36vdc on the MJ4502 and -36vdc on the MJ802,so i have no power supply problem. i am guessing what i am getting from the amp is all shes got.i'm thinking that it is overated by polytone.unless there is say 10 volts on the 15volt supply for the preamp.i mentioned earlier that the trace was cut at the opto isolator which is right after the large probably 3amp diodes on the first preamp board.i don't know if it was cut at the factory or someone cut it by accident.don't know if i fix the trace will i get smoke. who knows without a print.my buddy called diane back today and got the answering machine.looks like Roly wins this round.no answer from Ploytone....not counting on getting a print for the preamp section..thanks for the power supply print. it was right.i'll try to get a voltage reading off one of the voltage regulators legs and see if i get 15vdc supply voltage......ed

thanks for the schematic dr gonz78.the schematic number pa378b is the right schematic.the output tansistors are listed that i have mj4502 and mj802.i will try to check things out for you again juan.i goofed up i carried the unit back upstairs to get the transistor numbers off the transistors and i noticed i forgot to hook up the rca cable to the output board, so i didn't have a preamp signal going to the output which = no scope pattern.i screwed up sorry. i will redo the check for you later tonight....thanks...ed!

i can check the parts on the board ,but i need to extend the wires that go to the connectors as they are only about 2-3 inches long.i can't turn the board upside down to get at the board with this situation to measure anything with the power on due to this situation..i measured all the capacitors. transistors were checked with a diode test on my fluke 87iii meter and a radio shack diode tester and they all tested good.all resistors and diodes were also good.solder joints looked good.both 50volt 8200uf capacitors were checked and measured good on my sencore ca55 capacitor checker which tests caps under a load.if i had 4 molex connectors of the right size and gender i could extend the wires and check everthing.i'm sure that is what they did at polytone when they were in business....ed!!

lets see if this works! i cut and pasted the browser into this post....ed!


http://s1093.photobucket.com/user/edwardeffect1/library/#/user/edwardeffect1/library/POLYTONE%20TAURUS%20ELITE?sort=3&page=1&_suid=1375167601484007348028784194593

going to put the amp back together today to do more testing.thanks for your patience.it's 3:15am and i woke up thinking how to make this post so eveyone could view the pictures i took.i do my best thinking in my sleep.when i try to learn a guitar song i play it before i go to bed.then i end up playing the song back in my head during sleeping.it works...ed