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Thread: peavey 130 special

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    peavey 130 special

    Chanel switching i am no expert but can use a meter ill try to keep this short.had lost my output volume. And found a bad chip socket. Replaced chip and socket. Back running again plenty of power.here is the prob i never had a foot switch for amp got one off ebay.i just dont seem to hear it switching. Looked at schematic cked the wireing on foot switchs tip of jack is for reverb and middle for switching cks fine with meter. I did download oweners manual.it says the normal gain is not affected by post gain control? If i turn post gain way down or off no matter switch position i have almost no gain. By turning normal gain if i dont use the switch post gain turns up gain and normal gain turns up also.i can get the amp to sound good like this. Mabe i am just chasing my tail thanks for any help

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    Supporting Member gbono's Avatar
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    You can find schematics for most amps here:http://http://bmamps.com/Tech_sch.html

    Are you sure the footswitch is working properly?

    The footswitch controls/switches lead normal reverb on/off. Does your footswitch turn reverb on/off?

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    Senior Member Enzo's Avatar
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    FS is lower left in the drawing. It controls U2B. Does the output of that IC, pin 7, toggle up and down between +15 and -15 as you stomp the switch?

    If the post control controls the level in both channels, then Q15 is stuck on, either by fault itself or because the control signal to it is stuck, hence check U2B.

    Can we not use the word "gain" for level? The post gain control controls the level of signal. it can be confusing if we use the same word for both.
    Education is what you're left with after you have forgotten what you have learned.

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    sorry about the gain a d level i am going to ck that pin monday thanks for come back ill get back again

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    re 130

    Quote Originally Posted by bcclew View Post
    sorry about the gain a d level i am going to ck that pin monday thanks for come back ill get back again
    again i am no expert but i am trying i have been doing auto wiring and house wiring 60 years but this is different. looking at u2b and pin 7 black meter lead on chassis ground red on pin 7 i have 15v+nothing when switching stays the same thank for help

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    g1
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    How about at pin 6 of U2B ?
    Quote Originally Posted by Justin Thomas View Post
    In my ideal world, I'm not too loud - your room is too small!

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    Quote Originally Posted by g1 View Post
    How about at pin 6 of U2B ?
    not sure ill ck tonight ill rite them all down on that chip.and get back thanks again

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    ck pin 6 using ground from pin 5 i thought all but 2 pins had 15v? having said that i am going to put this on hold till jan 3ird or 4th i will be able to take the amp to work and set it up on a bench along with my computer and see with your help we can get to the bottom of this. have a good holiday andagain thanks for your help bcclew

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    Quote Originally Posted by bcclew View Post
    ck pin 6 using ground from pin 5 i thought all but 2 pins had 15v? having said that i am going to put this on hold till jan 3ird or 4th i will be able to take the amp to work and set it up on a bench along with my computer and see with your help we can get to the bottom of this. have a good holiday andagain thanks for your help bcclew
    jan 3 amp on bench going to ck pin 6? looking at the 8 legs on chip ub2 is the one near the index mark pin1? thanks

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    Quote Originally Posted by bcclew View Post
    jan 3 amp on bench going to ck pin 6? looking at the 8 legs on chip ub2 is the one near the index mark pin1? thanks
    trying to my head back in this.looking at ub2 and q15 am i cking ac or dc volts thonks

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    g1
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    You are checking for DC volts. If there is a round indent in the IC, yes that will be pin 1.
    Quote Originally Posted by Justin Thomas View Post
    In my ideal world, I'm not too loud - your room is too small!

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    Quote Originally Posted by g1 View Post
    You are checking for DC volts. If there is a round indent in the IC, yes that will be pin 1.
    thanks for come back.ok looking at ic pin1 0 p2 .072 p3 .093 p4 -4.75 counted from index mark on left as 1 stayed on left side down to 4 right side across from 1 as 5 so pin5 13.66 p6-3.3 p72.4 p8 0

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    g1
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    Here is how the IC numbering works:
    ne4558-pinout.jpg
    Quote Originally Posted by Justin Thomas View Post
    In my ideal world, I'm not too loud - your room is too small!

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    g1
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    It seems you do not have the correct power supplies going to pins 4 and 8.
    Do you have the correct + & - 15V at CR36 and CR37 ? (shown in lower right area of schematic)
    Quote Originally Posted by Justin Thomas View Post
    In my ideal world, I'm not too loud - your room is too small!

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    sorry for the delayi am having trouble finding cr36 &37 on circuit board. i can see the 5w units is cr36&37 diodes?on the 5w pieces -27.07&-4.79 on one 24.78&13.63 on the other i dont no if this helps?getting a little confused thanks

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    g1
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    Yes, those are the ones. Where you have -4.79 should be around -14 or -15V.
    One of the chips is probably loading down the voltage. Is U2 getting hot? Any of the other IC's getting hot?
    Also check the solder joints on those 5W diodes and resolder if they don't look right.
    Quote Originally Posted by Justin Thomas View Post
    In my ideal world, I'm not too loud - your room is too small!

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    i dont feel any heat i am going to pull the circuit board out and look on other side i had it out once maybe i missed something ill get back tomorrow thanks

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    Quote Originally Posted by bcclew View Post
    i dont feel any heat i am going to pull the circuit board out and look on other side i had it out once maybe i missed something ill get back tomorrow thanks
    ok took board out to look at other side.i have a good magnifying light all soldering looks good. i cked all the circuit tracks on board with dvom all were complete none broke or high resistance.i am still trying to get a handle on cr36&37 so when i put back i can try to re ck for that 15 volts

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    i didnt mention i changed all the ics i got them from peavey. and did index them like dia shows i did this about 4 years ago. never got back until now.

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    Quote Originally Posted by bcclew View Post
    i didnt mention i changed all the ics i got them from peavey. and did index them like dia shows i did this about 4 years ago. never got back until now.
    ok back again i got it cr36 has 13.66 on one side and 1.495 on other cr37 has -4.80 on one side and 1.495 on the other i found a dia of the other side of the board now i can see thanks

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    Senior Member Enzo's Avatar
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    Um... where are you grounding your meter for these readings? CR36,37 are zeners regulating the 15v supplies, and as such have one end grounded. But you have a volt and a half on what I presume is the ground end of both of them. Are all the board screws in placce holding the board into the chassis?

    Have we replaced CR37 yet?

    The ICs are in sockets, yes? Pull all four and power up, is the -15 still way low?

    CR36,37 are diodes, and look like litle cyliners with a stripe. Each has a 5 watt resistor associated, R97,98. 250 ohms, do they measure right at power off?
    Education is what you're left with after you have forgotten what you have learned.

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    putting black lead of volt meter on chassis had 4 screws back for this test. will put them all back and ck again. ill be back monday after 2pm ill ck with ics out thanks for all your help

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    also if i replace cr37 what am i asking for

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    Senior Member Enzo's Avatar
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    plain old 15v 1 watt zener diode, most commonly 1N4744. The 40102 is a Peavey house number.
    Education is what you're left with after you have forgotten what you have learned.

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    Quote Originally Posted by Enzo View Post
    plain old 15v 1 watt zener diode, most commonly 1N4744. The 40102 is a Peavey house number.
    Heading to raido shack get a diode also on sciatic it say voltage should be cked with switch closed not sure if I did that .what you think?

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    Quote Originally Posted by Enzo View Post
    plain old 15v 1 watt zener diode, most commonly 1N4744. The 40102 is a Peavey house number.
    ok back again cked vlotage with ics out on cr37 voltage went from 4.79 to 3.61.i got a new diode this number nti electronics zener diode nte 145a 15.0 vlots +5% pd 1W THIS IS BLACK WITH A SILVER STRIPE IF THATS RIGHT SHOULD I CHANGE IT?AND DOES THE STRIPE FACE THE 4.79 SIDE OR THE 1.495 SIDE

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    Stripe should go where you had 1.495
    Quote Originally Posted by Justin Thomas View Post
    In my ideal world, I'm not too loud - your room is too small!

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    Senior Member Enzo's Avatar
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    Stripe should go where the stripe was on the original part. Also, the parts layour drawing with the schematic shows parts orientations.

    I am betting on that zener, but do the tests with the ICs out. If the voltage remains low, putting the ICs back in wonlt raise it. We need to solve teh low voltage before the ICs return.
    Education is what you're left with after you have forgotten what you have learned.

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    Put diode in got -17.31 where we had 4.80 ic pin 8 13.64 pin 4 17.31 went to pin 7 had -1.347 clicking switch -0.752 also when clicking switch i hear a slight pop in speaker

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    i did test with ics in do you want me to take them out? ill do it tomorrow 9.25 pm heading home thanks

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    i took a gamble hooked up guitar and channel switching works!!!!!!!! that 17.31 voltage is higher than 15 should i be concrened about that i will try amp at home where i have more time.if that voltage is not going to be a problem. thanks for all the help i learned a lot on this fourm.but a lot more to go if i live that long.thanks again bcclew

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    1/11/17 played amp for about 1&1/2 hours seems to work fine didnt put it back in cabinet yet just in case somebody gets back abou the 17 volts. thanks again.i know this is an amp forum but if you guys need any car help shoot me a personal hit be glad to help thanks again

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    g1
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    It seems that the CR37 voltage is a bit high, and the CR36 voltage is a bit low.
    But you also mentioned that the common point is not at zero, but at 1.495. Is it still not zero at the other end of CR37?
    Are all the grounds connected and board mounting screws in place?
    Quote Originally Posted by Justin Thomas View Post
    In my ideal world, I'm not too loud - your room is too small!

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    all mounting screws are in ill ck tonight BUT I REALLY DIDNT SEE ANY OTHER GROUND WIRES EXCEPT IN THE PLASTIC PLUGS AND THEY LOOKED OK BUT ILL CK TONIGHT ON THAT VOLTAGE THANKS

  35. #35
    Senior Member Enzo's Avatar
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    Not so much a missing ground wire, but perhaps a broken or burnt off ground trace on the board. Measure resistance to chassis from the "ground" point of the two zeners. It SHOULD read zero ohms or close.
    Education is what you're left with after you have forgotten what you have learned.

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