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  • Reactive Load attenuator needs Tech service

    I have this Attenuator called The Power Tool (PS Systems EB100S Digital-MIDI Tube Guitar Amplifier) It is now 21 yrs old..I hardly use the attenuayor ,but I run a tube preamp and my Rack reverbs and delays into it...I hooked up a 100 watt Marshall to it the other day and after a 1/2 hour the tubes started pumping or flashing Blue gas ..I only had the amp volume on 4 and it was distorting...When I plugged it in normal all the blue gas went away..When I plug just a tube preamp in it almost sounds normal ,but after 5 monutes the volume will drop and then or high...would 21 yr old Filter Caps Be problem...What I really need is someone who knows how to trouble shoot...This is a nice piece or gear and really been well taken care of...but I have called a few places down in Orange County California,and no one will touch it..I went trough it the best I could and I did not "see" anything wrong...It still works, but not like it should..If you can help,or point me to someone...Anyone who remembers my 63 Bandmaster here and all the problems I had with Kendricks amps,and all that was wrong was a bad ground wire and they switched the power tube plate wires around Thanks DAB

  • #2
    It is NOT the Midi Tube Guitar AMP, that looks like a spaceship control..... Just The Power Tool reactive load...on the right...

    Comment


    • #3
      I cannot find any references to this unit.

      So what is 'inside' the unit?

      Are there any switches (that may be dirty, corroded)?

      Adam's Amplifiers: Attenuation

      Comment


      • #4
        Originally posted by Jazz P Bass View Post
        I cannot find any references to this unit.

        So what is 'inside' the unit?

        Are there any switches (that may be dirty, corroded)?

        Adam's Amplifiers: Attenuation
        The only thing there is is at www. eb100s.com There are no shematics only what it does... I cleaned it with D-oxit What I need is some one who is good at trouble shooting and sending it to them...I know It can't be a huge deal..... I was thinking Filter Caps being 21 yrs old would that make power tubes flash and volume go up and down...

        Comment


        • #5
          I thought you wanted the power soak worked on.

          Comment


          • #6
            Originally posted by Jazz P Bass View Post
            I thought you wanted the power soak worked on.
            It is not a soak.....Reactive load with a 50 watt SS power amp built in....I thought I would ask around here...If anyone ever worked on one like this

            Comment


            • #7
              Originally posted by dumbassbob View Post
              It is not a soak.....Reactive load with a 50 watt SS power amp built in....I thought I would ask around here...If anyone ever worked on one like this
              1) don't get hung on semantics, call it soak or not it is a tube amp load box, which then turns amp output into line level signal and then reamplifies it with an SS amp to actually drive the speakers.

              Particular details :

              a) it is a reactive load.

              b) I think you only have the module called "The Power Tool" :
              http://www.pacair.com/mmamps/EB100S/...ool_Manual.pdf

              c) it has its own tone controls, which affect the signal fed to it

              d) it has an EQ setting which claims to make a Twin sound like a 4x12" Marshall closed back cabinet.
              Not on a line out send to mixer but on the actual speaker cabinet, at stage levels.
              Would love to hear that

              e) it accepts speaker or preamp/line signals

              2) what is the real problem you want to correct?
              That the amp tubes show blue glow which pulses with music?
              That "somehow it does not sound right?"

              No wonder nobody wants to touch it.
              Juan Manuel Fahey

              Comment


              • #8
                Originally posted by J M Fahey View Post
                1) don't get hung on semantics, call it soak or not it is a tube amp load box, which then turns amp output into line level signal and then reamplifies it with an SS amp to actually drive the speakers.

                Particular details :

                a) it is a reactive load.

                b) I think you only have the module called "The Power Tool" :
                http://www.pacair.com/mmamps/EB100S/...ool_Manual.pdf

                c) it has its own tone controls, which affect the signal fed to it

                d) it has an EQ setting which claims to make a Twin sound like a 4x12" Marshall closed back cabinet.
                Not on a line out send to mixer but on the actual speaker cabinet, at stage levels.
                Would love to hear that

                e) it accepts speaker or preamp/line signals

                2) what is the real problem you want to correct?
                That the amp tubes show blue glow which pulses with music?
                That "somehow it does not sound right?"

                No wonder nobody wants to touch it.
                Yes... The problem is the uneven distortion and it makes the Power tubes flash blue when you strum..The thing worked so well for all these years....Could a 22 yr old filter caps be going?There are (2) 22000 and a 22000 RF 100 volt cap...When I only use the Line In with a TubePreamp and a digital reverb pluged in to the fx loop it seems OK...Cleaning it with Doxit also seems to have helped..Some of the "POTS" are huge for EQ and to make it sound 4x12 I have never seen pots like these....Someone who knew what they were doing I bet can find what is wrong...The PT looks like it was well made....This was the first time I was ever inside of it

                Comment


                • #9
                  How about a few pics?

                  Comment


                  • #10
                    Originally posted by dumbassbob View Post
                    Yes... The problem is the uneven distortion and it makes the Power tubes flash blue when you strum..
                    1) that the tubes flash blue in rhythm with the music is normal, when they are being driven hard, so don't worry about that.

                    2) that "distortion is uneven" makes me think that the head you are using to drive the Attenuator is plain clipping/overdriving.

                    3) problem is, that from 1) and 2) I deduce you are driving your Marshall hard , it distorts, and plain you don't like it, which I respect, it's a question of taste.

                    4) driving the same Attenuator from a preamp/line output sounds "good" because you are not going through the power stage, avoiding its distortion.

                    5) maybe you don't think your amp is that loud, but it is, simply all that power is being dissipated in the internal load resistor, designed to take 100 Watts.

                    6) Just do this little experiment: plug your Marshall head in this Attenuator, set it as before (so "tubes glow blue", "sounds ugly"), then turn both off, without touching anything plug the head straight into the 4x12" cabinet, turn head on (remember, do not vary ANY setting) and play.
                    I bet it will sound "funny" as before, tubes will glow blue ... and sound will be DEAFENING.


                    The thing worked so well for all these years....
                    You are using it in a different way.
                    By your own statement, when using it again with preamp and digital reverb it works fine ... so ... nothing broke.

                    Could a 22 yr old filter caps be going?There are (2) 22000 and a 22000 RF 100 volt cap...
                    Up to a year ago, everybody thought "it's the transformer, isn't it?" , the last trend is blame the capacitors and replace them without troubleshooting.
                    No, even if caps were bad they would not explain what you describe.

                    Doubly so because:
                    When I only use the Line In with a TubePreamp and a digital reverb pluged in to the fx loop it seems OK...
                    Cleaning it with Doxit also seems to have helped..
                    Never hurts.

                    Some of the "POTS" are huge for EQ and to make it sound 4x12 I have never seen pots like these....
                    Probably pots are very good, even MilSpec or something (Bourns?) but pots alone don't EQ, I bet there is quite a circuit behind them.

                    Someone who knew what they were doing I bet can find what is wrong...The PT looks like it was well made....This was the first time I was ever inside of it
                    No doubt.
                    It must have been expensive too.

                    So please do the head>cabinet test (previously setting it through the Attenuator) and post results.
                    Juan Manuel Fahey

                    Comment


                    • #11
                      There is still no clear description of what you are doing and which tubes are glowing and pumping, the Marshall or the built-in amp. You say is sounds good for a while but becomes distorted.
                      The big pots might be L-Pads for high level EQ at the output of the built-in amp. There is just to much ambiguity to make any guess as to what is happening. From the description is has an amplifier driving a soak, I assume there is a line level output from the soak. What level does it put out when the built-in amp clips? It is possible all the problems are related to a mismatch of the line output, or a problem in either the soak amp plus the Marshall has not been ruled out.
                      So first off, which amp is dying and which has the blue tubes(not a problem unless it is not a faint light blue seen mostly around cut outs in the plate structure of the tubes. Are all the tubes doing the same degree of blue cloud?

                      Comment


                      • #12
                        Originally posted by km6xz View Post
                        There is still no clear description of what you are doing and which tubes are glowing and pumping, the Marshall or the built-in amp. You say is sounds good for a while but becomes distorted.
                        The big pots might be L-Pads for high level EQ at the output of the built-in amp. There is just to much ambiguity to make any guess as to what is happening. From the description is has an amplifier driving a soak, I assume there is a line level output from the soak. What level does it put out when the built-in amp clips? It is possible all the problems are related to a mismatch of the line output, or a problem in either the soak amp plus the Marshall has not been ruled out.
                        So first off, which amp is dying and which has the blue tubes(not a problem unless it is not a faint light blue seen mostly around cut outs in the plate structure of the tubes. Are all the tubes doing the same degree of blue cloud?
                        The Power Tubes in the Marshall are flashing Blue they do not do it when plugged into cab I only have the Volume on 4 but using a 2x12 cabnit with Fane 30 watt speakers The Pots are Bourns? huge never seen pots like that Not the size,but how fat they are.....I drained the amp and have it down in the garage checking for burned wires to the OT...I do take good care of my guitars and amps..I don't dime the Marshall and that Bandmaster sounds great..I paid $800.00 22 yrs ago or the "soak" After I clean the Marshall and check the wires I will get back...I thought maybe the speakers but that doesn't matter I can use a headphone if I want..I used the Power Tool yesterday with a tube preamp into the 2x12 cab It was OK Thanks DAB

                        Comment


                        • #13
                          You are maddeningly vague when answering and/or answer "something else", not what was asked.

                          Again:
                          6) Just do this little experiment: plug your Marshall head in this Attenuator, set it as before (so "tubes glow blue", "sounds ugly"), then turn both off, without touching anything plug the head straight into the 2x12" cabinet, turn head on (remember, do not vary ANY setting) and play.
                          Just this.

                          Do not tell me about your Fane speakers, the Bandmaster, how much you paid, etc. because I'm not interested, is irrelevant to the problem.

                          You are asking for help, fine.

                          We don't have that setup on the bench, you do, so you test and measure and post results.

                          Anything else is just wild guessing or idle chat.

                          Thanks.
                          Juan Manuel Fahey

                          Comment


                          • #14
                            Originally posted by J M Fahey View Post
                            You are maddeningly vague when answering and/or answer "something else", not what was asked.

                            Again:

                            Just this.

                            Do not tell me about your Fane speakers, the Bandmaster, how much you paid, etc. because I'm not interested, is irrelevant to the problem.

                            You are asking for help, fine.

                            We don't have that setup on the bench, you do, so you test and measure and post results.

                            Anything else is just wild guessing or idle chat.

                            Thanks.
                            ++1.
                            Bob,
                            Please do your best to stay on topic and answer the questions. It will really help people help you.

                            Comment


                            • #15
                              Originally posted by J M Fahey View Post
                              1) that the tubes flash blue in rhythm with the music is normal, when they are being driven hard, so don't worry about that.

                              2) that "distortion is uneven" makes me think that the head you are using to drive the Attenuator is plain clipping/overdriving.

                              3) problem is, that from 1) and 2) I deduce you are driving your Marshall hard , it distorts, and plain you don't like it, which I respect, it's a question of taste.

                              4) driving the same Attenuator from a preamp/line output sounds "good" because you are not going through the power stage, avoiding its distortion.

                              5) maybe you don't think your amp is that loud, but it is, simply all that power is being dissipated in the internal load resistor, designed to take 100 Watts.

                              6) Just do this little experiment: plug your Marshall head in this Attenuator, set it as before (so "tubes glow blue", "sounds ugly"), then turn both off, without touching anything plug the head straight into the 4x12" cabinet, turn head on (remember, do not vary ANY setting) and play.
                              I bet it will sound "funny" as before, tubes will glow blue ... and sound will be DEAFENING.



                              You are using it in a different way.
                              By your own statement, when using it again with preamp and digital reverb it works fine ... so ... nothing broke.


                              Up to a year ago, everybody thought "it's the transformer, isn't it?" , the last trend is blame the capacitors and replace them without troubleshooting.
                              No, even if caps were bad they would not explain what you describe.

                              Doubly so because:



                              Never hurts.


                              Probably pots are very good, even MilSpec or something (Bourns?) but pots alone don't EQ, I bet there is quite a circuit behind them.


                              No doubt.
                              It must have been expensive too.

                              So please do the head>cabinet test (previously setting it through the Attenuator) and post results.
                              I was driving it way to hard ..A 100watt PLexi puts out 175 watts even when the volumes on 5...Funny Marshall sells that power brake but in the History of Marshall book It said to Never use any attenuator... void warranty...Cleaning it and not turning the volume up past #2 it is fine...The power tool manual shows a 100 watt Marshall..."turn it to 10"

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