Members Iron Lotus Posted March 11, 2008 Members Share Posted March 11, 2008 Okay, I had it wired up the regular way for a couple years,,, Since I had to go in and replace a resistor, I just did new stuff, Since I had the whole board out I wired it on the other side because it doesnt get much more stock than that, and used the 5.6k resistor in place of the 15k. Also used a 10k pot that goes outside the amp in between the circuit so I can adjust the bias. In the pic the black capacitor is the same value as the blue ones, but they didnt have the blue ones, Same exact thing though. My question is how can I wire up the test points to make them useful, I did have the + test point going to one side of the capacitor (the now black one beside the 2 blue ones), And the - test point going to the other side of the capacitor from the test points... Theres probably no way to wire them to where I could get a mA reading is there? Link to comment Share on other sites More sharing options...
Members tommythelurker Posted March 11, 2008 Members Share Posted March 11, 2008 Cut that lead on the resistor shorter and use some head shrink to cover up the exposed lead. For the test points, get some 1 ohm 1% 5W resistors and install them between the cathode of the power tubes and ground (one per tube). You can hook the test points up in parallel two all four tubes, or 2 pairs (will give you an "average" of the parallel tubes) or 4 test points to measure the tubes individually. Link to comment Share on other sites More sharing options...
Members 496dart Posted March 11, 2008 Members Share Posted March 11, 2008 EDIT===you beat me to it Tommy .. you will need another red/positive test jack . you could do it so you are measuring each side of the OT (plates to ct). I wouldnt do it that way ... Or, the much safer way , would be to install 1 Ohm resistors from cathode to ground on the power tubes and wire it so you can measure across those resistors (in Mv) . i would also at least hot glue those wires and resistor to the board in the pic. Link to comment Share on other sites More sharing options...
Members Casey4s Posted March 11, 2008 Members Share Posted March 11, 2008 Okay, I had it wired up the regular way for a couple years,,, Since I had to go in and replace a resistor, I just did new stuff, Since I had the whole board out I wired it on the other side because it doesnt get much more stock than that, and used the 5.6k resistor in place of the 15k. Also used a 10k pot that goes outside the amp in between the circuit so I can adjust the bias. In the pic the black capacitor is the same value as the blue ones, but they didnt have the blue ones, Same exact thing though. My question is how can I wire up the test points to make them useful, I did have the + test point going to one side of the capacitor (the now black one beside the 2 blue ones), And the - test point going to the other side of the capacitor from the test points... Theres probably no way to wire them to where I could get a mA reading is there? All you have to do is put a ONE ohm 2 watt resister in each of the cathode leads going to ground. Then run your wire to the test point from the tube side of the resistor. You will also have to have an accessable ground reference from the oter side of the resistor. So you are actually reading the voltage accoss the resistor. So because the reisitor is one ohm it is a direct conversion (ohms law) to mA. If you read 35mV it is the same as 35 mA. I haven't seen the schematic for this amp so if your cathodes are all grounded together your reading will be for the total of the tubes combined. If the cathodes are grounded in pairs you will need two test points, one for each cathode ground. EDIT: Damn, looks like we were all typing at the same time! Link to comment Share on other sites More sharing options...
Members tommythelurker Posted March 11, 2008 Members Share Posted March 11, 2008 If you read 35mv it is the same as 35 mA. Fixed Link to comment Share on other sites More sharing options...
Members Iron Lotus Posted March 11, 2008 Author Members Share Posted March 11, 2008 EDIT===you beat me to it Tommy .. you will need another red/positive test jack . you could do it so you are measuring each side of the OT (plates to ct). I wouldnt do it that way ... Or, the much safer way , would be to install 1 Ohm resistors from cathode to ground on the power tubes and wire it so you can measure across those resistors (in Mv) . i would also at least hot glue those wires and resistor to the board in the pic. Definatly going to be hot gluing, That is when everything is in place and working to spec. Can you give me a more detailed description of the wiring using the test points? Like a paint diagram? And thanks to you both for the replies, Just want to be sure before I start wiring and have to redo it. I dont want to have to open this amp up for a long time Link to comment Share on other sites More sharing options...
Members Iron Lotus Posted March 11, 2008 Author Members Share Posted March 11, 2008 All you have to do is put a ONE ohm 2 watt resister in each of the cathode leads going to ground. Then run your wire to the test point from the tube side of the resistor. You will also have to have an accessable ground reference from the oter side of the resistor. So you are actually reading the voltage accoss the resistor. So because the reisitor is one ohm it is a direct conversion (ohms law) to mA. If you read 35v it is the same as 35 mA.I haven't seen the schematic for this amp so if your cathodes are all grounded together your reading will be for the total of the tubes combined. If the cathodes are grounded in pairs you will need two test points, one for each cathode ground. Schematics for the amp...http://blueguitar.org/schems.htm#Peavey Link to comment Share on other sites More sharing options...
Members tommythelurker Posted March 11, 2008 Members Share Posted March 11, 2008 I can't be more specific about the cathode resistors without seeing a layout. IIRC the power tubes are board mounted which may make it a little tricky. Maybe Jerryp will chime in, I think he has a lot of experience tinkering with this amp and may be able to give you more specifics. Link to comment Share on other sites More sharing options...
Members Casey4s Posted March 11, 2008 Members Share Posted March 11, 2008 Schematics for the amp...http://blueguitar.org/schems.htm#Peavey There looks like two good ways to do this on this amp. (1) put the one ohm resistor (2W) on each of the cathodes. pin #8 to the J13 wire to ground and have four seperate test points. (2) put a single one ohm (5W) resistor to the right (on the schematic) of the second pair of power tubes on the J15 wire and have a single test point for the total of the four tubes. Link to comment Share on other sites More sharing options...
Members Casey4s Posted March 11, 2008 Members Share Posted March 11, 2008 Fixed Thanx Tommy....I was asleep at the wheel. Link to comment Share on other sites More sharing options...
Members Iron Lotus Posted March 11, 2008 Author Members Share Posted March 11, 2008 standing here and thet only have 1ohm 5% 5watt or 1ohm 2% 2watt.. i only want 1 set of test points so which should i buy? im gonna need a kiddie diagram dudes haha copy a picture and circle some stuff and connect some lines and ill be good to go when i get outta this store and back to my amp! Link to comment Share on other sites More sharing options...
Members Iron Lotus Posted March 11, 2008 Author Members Share Posted March 11, 2008 bump which resistor so i can leave the electronic store already Link to comment Share on other sites More sharing options...
Members tommythelurker Posted March 11, 2008 Members Share Posted March 11, 2008 Neither. Internet.You may not even get the dumbed down instructions you need, probably should just take it to a tech or get a bias probe. Actually, if you had to buy one at the store, I guess you could get away with a 2% Link to comment Share on other sites More sharing options...
Members Iron Lotus Posted March 11, 2008 Author Members Share Posted March 11, 2008 Neither. Internet.You may not even get the dumbed down instructions you need, probably should just take it to a tech or get a bias probe.Actually, if you had to buy one at the store, I guess you could get away with a 2% if i wanted a tech to do it i wouldnt be doing it. i want to know its to my satisfaction and plus im not made of money. i do most everything myself and i learn a whole lot more that way i dont need to run to a tech if im on the road and my amp goes down.. i need to be able to handle it myself with some experiance and a little guidance from time to time. ill go ahead and buy the 1ohm 2watt 2% i really dont have time to internet order things right now bro Link to comment Share on other sites More sharing options...
Members tommythelurker Posted March 11, 2008 Members Share Posted March 11, 2008 Do want you want, but if you keep trying to tackle things that are over your head and rushing them, it's going to bite you in the ass one of these days. Link to comment Share on other sites More sharing options...
Members Iron Lotus Posted March 11, 2008 Author Members Share Posted March 11, 2008 Do want you want, but if you keep trying to tackle things that are over your head and rushing them, it's going to bite you in the ass one of these days. oo how did they learn. it wast always some school... experience IS the best teacher so ill take my chances tom. not the most difficult thing ive ever done im sure. im not afraid of gettin "bit in the ass" every once in a while.. i learn from it. taking it to a tech would have taught me nothing in the first place. Link to comment Share on other sites More sharing options...
Members tommythelurker Posted March 11, 2008 Members Share Posted March 11, 2008 oo experience IS the best teacher Not always. Some mistakes you only get to make once. Link to comment Share on other sites More sharing options...
Members Iron Lotus Posted March 11, 2008 Author Members Share Posted March 11, 2008 Not always. Some mistakes you only get to make once. and this isnt one of them so chill with that shit and lets be friends Link to comment Share on other sites More sharing options...
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