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moonmarkcus
Silver Member
Nicaragua
224 Posts |
 Posted - 11/10/2009 : 19:06:51
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Hi everybody, im tring to fix an AMT Fatal Tube Overdrive. Simptons are following.
1. When effect is off, pedal let pass a distorted sound of guitar.
2. When effect in on, pedal doesnt sound ( mute at all)
pedal has discrete components ( as you can see on pictures) and I noticed TL062 opamps inside ... I have a lot of good experiences repairing my Boss analog pedals, but I dont known how can troubleshoot this kind of pedal... Please give me ideas in order to understand how it works and probably resurrect this nice pedal!!!
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cctsim
Silver Member
United Kingdom
418 Posts |
Posted - 11/10/2009 : 21:11:34
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| Did you manage to find a schematic for this pedal ? If so, can you post the link ? |
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moonmarkcus
Silver Member
Nicaragua
224 Posts |
Posted - 11/10/2009 : 21:37:50
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quote:
Originally posted by cctsim
Did you manage to find a schematic for this pedal ? If so, can you post the link ?
Hello my friend. 
I dont have any document about it, I was seeking last 3 days on Internet without success!! 
Do you have any idea to begin this repair process ?? 
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cctsim
Silver Member
United Kingdom
418 Posts |
Posted - 11/10/2009 : 22:09:34
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It looks like the switching circuit is not working properly.
Is it true bypass or electronic switching ? I can't tell from the pictures.
What are the ICs ? Can you post their labels ? |
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moonmarkcus
Silver Member
Nicaragua
224 Posts |
Posted - 11/11/2009 : 00:02:50
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Most of them are TL062, tomorrow I will edit pictures in order to show you every IC with related label...it supossed to be "true bypass"
Do you need any more pic? |
Edited by - moonmarkcus on 11/11/2009 00:06:20 |
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cctsim
Silver Member
United Kingdom
418 Posts |
Posted - 11/11/2009 : 01:10:27
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If it's true bypass the symptoms indicate a failure of the switch.
It should be easy to follow the path from the input jack, to the 3PDT, to the output jack.
Is it 3PDT ?
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moonmarkcus
Silver Member
Nicaragua
224 Posts |
Posted - 11/11/2009 : 19:27:01
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Switch doesnt seem to be like 3DPT, inside it has a spring that push a switch on board.
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Dr. Bob
Moderator
Australia
6593 Posts |
Posted - 11/12/2009 : 07:10:48
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Hi moonmarkcus
I went to all my technical & Chip databases.
I spent at least 30-40 mins searching, but I was unable to locate
any data on the Phillips BE878-01.
I have a question for you, actually the manufacturer.
Where is the Tube?
They call it the AMT Fatal "Tube" Overdrive, & have a picture, of a small twin triode "tube" on the artwork of the case.
But I don't see any tubes or tube sockets, talk about deceptive marketing.
The board mounted push button switch, will be controlling something similar to a flip flop circuit in the Boss pedal for bypass.
Do you know what happened to it before it stopped working?
Have you traced the DC power in - does it go to a protection diode?
Is the diode open circuit?
If it was reveresed voltage, & the diode is open, I'll bet good money
that the all or some of the opamps are fried.
As I've mentioned many many times before, op-amps HATE REVERSE Volts.
Good luck with your repair.
Pity you don't live closer, we could have a look at it together.
I still want to see where the tube goes... 
Regards Dr. Bob 
5959 |
Edited by - Dr. Bob on 11/12/2009 07:12:10 |
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moonmarkcus
Silver Member
Nicaragua
224 Posts |
Posted - 11/12/2009 : 18:56:13
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HI Dr!!
Where is the Tube? Good question  , Maybe was disintegrated by reverse voltaje !!!!  Nahhhh, it supposed to be simulated by circuit  , I guess the word "Tube" is the hook , so I dont think we will found any tube, at least we will deploy a new nice mod!!!
I dont know how can I found protection diodes on discrete components PCB,Only thing that I know:DC adapter is supplying power and ON/OFF effect LED is working
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cctsim
Silver Member
United Kingdom
418 Posts |
Posted - 11/12/2009 : 19:33:57
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My suggestion is to take out the footswitch and check that is working properly.
The description of the fault suggests that something unusual is happening there. |
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bside2234
Copper Member
USA
15 Posts |
Posted - 11/13/2009 : 18:37:25
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| Also with those board mounted input/output jacks, it couldn't hurt to check the joints on them. I would reheat them just for good measure. |
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Topic |
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How can repair an AMT Fatal Tube Pedal???
