Mad Professor 1

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Re: Mad Professor 1

Postby Ice-9 » 11 Jul 2017, 09:46

Thanks caspercody, if you still have the pedal apart can you read the 3 sot23 packages please, one is top left of the pots pcb just above the reverb pot, the other two are on the bottom pcb, one to the left of the footswitch and the other marked dx1 looks like a two diode device and markings look like 8F ?
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

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Re: Mad Professor 1

Postby rmroza » 11 Jul 2017, 13:44

I'm back from vaca. Let me know if anyone needs anything for the "1" or "Mighty Red" and let's figure this out.
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Re: Mad Professor 1

Postby rmroza » 11 Jul 2017, 14:02


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Re: Mad Professor 1

Postby Ice-9 » 11 Jul 2017, 18:16

Can anyone tell me if pins 14/15 of the NE570 connect to anything ? :hmmm:

EDIT- it looks like I might be getting one of these in for repair this week, symptoms - no power, should be a simple fix but will see if I can take a closer look at what's going on inside. :)
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?

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Re: Mad Professor 1

Postby Ice-9 » 12 Jul 2017, 11:44

Sorry, the repair won't be coming in as when I spoke to the owner I found he was trying to use a centre positive PSU, so when tried with the correct PSU the pedal works fine :(
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?
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Re: Mad Professor 1

Postby caspercody » 12 Jul 2017, 17:27

I will try to look for part numbers tonight, let me know if anything else to look at?
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Re: Mad Professor 1

Postby caspercody » 13 Jul 2017, 03:24

The one by the reverb pot is T1 and is labeled GX2.

The one to the left of the 3PDT switch is D3 and labeled 8F. I do not see the third one.

There are no markings on the caps.

I have started to list out the resistors, might take a little bit to get them all. Does anyone want this list?
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Re: Mad Professor 1

Postby Ice-9 » 14 Jul 2017, 17:58

caspercody wrote:The one by the reverb pot is T1 and is labeled GX2.

The one to the left of the 3PDT switch is D3 and labeled 8F. I do not see the third one.

There are no markings on the caps.

I have started to list out the resistors, might take a little bit to get them all. Does anyone want this list?


So can anyone identify the parts from the codes of these 3 SOT23 parts
what we know so far....

T1 = GX2 and I am going to presume it is a transistor because of the T1 screen on the PCb

DX1 and D3 = 8F I presume these are diodes with possibly two diodes in the one package ?

8F looks like it could be a 5.1v single zener diode http://www.s-manuals.com/pdf/datasheet/ ... vishay.pdf
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

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Re: Mad Professor 1

Postby deltafred » 14 Jul 2017, 19:44

From the SMDCookbook.pdf / The SMD Code Book.pdf

I cannot see anything for GX2

8F comes up as the following so probably the zenner
NJM78L07A - SOT89 - 7V 0.1A regulator
MMBZ5231B - SOT23 - 5.1V Zenner 0.225W
MUN2216 - NPN Transistor
MUN5216 - NPN Transistor
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Re: Mad Professor 1

Postby caspercody » 15 Jul 2017, 15:17

Here are some more pictures of the tracing. I also made a list of all the parts I saw. I measured the caps with a DMM. The settings for the DMM I wrote on the top of caps Jpeg. These are the settings on the DMM to select when measuring the farads. Not sure if this means anything.

I put it back together. Hope this helps.

Thanks
Rob
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Re: Mad Professor 1

Postby caspercody » 15 Jul 2017, 15:20

T1 I wrote before as (GX2) was wrong. I think it is 6X3 or GX3. Sorry about that.
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Re: Mad Professor 1

Postby Ice-9 » 15 Jul 2017, 16:24

caspercody wrote:T1 I wrote before as (GX2) was wrong. I think it is 6X3 or GX3. Sorry about that.


T1-6X looks like it could be a BF545A n channel jfet transistor.
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

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Re: Mad Professor 1

Postby bool » 16 Jul 2017, 13:06

BF545A is supposed to be a SMD version of the old skool tru-hole BF245A.

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Re: Mad Professor 1

Postby caspercody » 21 Jul 2017, 03:31

This was emailed to me by someone that does not want to be known, but said it was alright to post.

Some of their comments on the schematic are:

Regarding the Schematic, while all the component values should be correct on the schematic some of the component numbering may not match the numbers on the PCB, this is due to Diptrace re-numbering components automatically when a component is added. This is an annoying feature of the program . Ie if you re-number a component lets say R1, if there is already an R1 it will auto number it to the next number =R2 as well as incrementing every other R one up.

I have attached the latest version of the MP1 schematic, I am quite sure this is 100% correct with the amendments to replace the two diodes just after the FV-1 with the correct T1 component and the bypass switch has been added, the led switching part of the bypass is a little strange as it also switches the ‘brown’ pot to minimum which is either quite a clever idea or I have missed the point of that.

I have breadboarded from the input upto the tone stack and with the schematic used it sounds like a great VH sound, I need to add the expander and following buffers to the breadboard

Thanks
Rob
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Re: Mad Professor 1

Postby bajaman » 21 Jul 2017, 07:07

excellent work :D
The op amps will no doubt be smd versions of the CA3130EZ that Bjorn favours in most of his designs - a very fast Bimos input stage followed by a bipolar gain stage and then a complementary CMOS output stage that swings almost rail to rail (within 10mv according to the intersil data sheet) :wink:
If this is the case then the 120p compensation capacitors should be connected between pins 1 and 8 (not 5 and 8 ) :hmmm:
A bit more advanced design from Bjorn this time - love the use of the compandor chip.
I have one of these coming from California so the schematic will be very helpful for future tweaking :lol:
chers guys
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Re: Mad Professor 1

Postby FuzzMonkey » 21 Jul 2017, 11:12

Nice work indeed.
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Re: Mad Professor 1

Postby Ice-9 » 21 Jul 2017, 16:39

bajaman wrote:excellent work :D
The op amps will no doubt be smd versions of the CA3130EZ that Bjorn favours in most of his designs - a very fast Bimos input stage followed by a bipolar gain stage and then a complementary CMOS output stage that swings almost rail to rail (within 10mv according to the intersil data sheet) :wink:
If this is the case then the 120p compensation capacitors should be connected between pins 1 and 8 (not 5 and 8 ) :hmmm:
A bit more advanced design from Bjorn this time - love the use of the compandor chip.
I have one of these coming from California so the schematic will be very helpful for future tweaking :lol:
chers guys
bajaman


The op-amps are NE5534's the compensation caps are connected to pins 5+8 which can be seen from the pictures. I'm sure Bjorn mentioned the IC's should be AD797's but it looks like they have all been replaced with NE5532's £10 v's £0.60 each :hmmm:
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?
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Re: Mad Professor 1

Postby Ice-9 » 21 Jul 2017, 19:58

Ice-9 wrote:
The op-amps are NE5534's the compensation caps are connected to pins 5+8 which can be seen from the pictures. I'm sure Bjorn mentioned the IC's should be AD797's but it looks like they have all been replaced with NE5532's £10 v's £0.60 each :hmmm:


Too late to edit but
I made a typo and meant to say NE5534's at £10 a pop :oops:
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?
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Re: Mad Professor 1

Postby bajaman » 21 Jul 2017, 23:31

:hmmm: thanks Ice-9 :wink:
I wonder how it would sound with the CA3130 devices then ?
Many folks have made comments comparing Bjorn's hand built BJFE pedals and the MP factory production versions sounding completely different. I have not seen any MP pedals using the CA3130 devices, they seem to be AD797 mostly. Not surprised that MP are not using CA3130 devices in this case, and although the pedal was supposedly designed by Bjorn, i see on the MP website that it ("1") was made exclusively for the Guitar Centre chain and so it is unlikely Bjorn will ever produce a handmade BJFE equivalent, but if he did decide to do so, I would think he would use the CA3130 like in all his other hand built designs :?:
Maybe Bjorn might like to comment on this :wink:
I know he parted company with MP company earlier this year as their chief designer of production MP pedals, so maybe he won't wish to make any further comment, and that's cool by me.
cheers
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Re: Mad Professor 1

Postby bajaman » 03 Aug 2017, 02:22

Just received my MP1 this morning - gave it a try and was a little disappointed in it - great reverb, BUT no way to run it without the distortion :cry:
After building the Friedman BE-OD and the Diezel VH4 designs I was looking forward to comparing them to the MP1 but it comes a distant third place as far as I am concerned.
OK - my main criticism is that the lowest gain (brown) setting is still way to much - perhaps a small toggle switch could have been added to select lower gain mode :hmmm:
And - a small toggle to defeat the gain stages completely while allowing footswitch control of the reverb would have been a nice feature too :wink:
I think I feel a challenge coming on :thumbsup
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