Anyone plug 12v DC ont a TS-9 Tube screamer?
Old 31st December 2010
  #1
Gear Head
 

Thread Starter
Anyone plug 12v DC ont a TS-9 Tube screamer?

Well, I did.

I just bought it too and the thing smoked inside and upon closer inspection it looks as though I blew just a diode next to the DC terminal. I went to the local electronics shop and got me some diodes and replaced the blown one, I have done repairs in the past but I am nowhere near proficient in electronics repair. So after the repair I plug it in to my Line 6 and hear nothing, I have to crank my amp WAY too high to start hearing something and when I do hear something it sounds "clipped" and lots of hiss. Obviously it's most likely still broke, but I don't see anything else wrong with it. Should I start doing test on connections (I do own a multimeter) what would I be looking for in my testing?

I know this is a handful but thanks to anyone who tries.

I can post pics if needed.
Old 31st December 2010
  #2
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yes post pics.

don't worry it may be quite simple.

you plugged in 12v dc. what was it expecting?
Old 31st December 2010
  #3
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heres a schematic, i presume it wanted 9v dc as it takes batteries


what diodes did you replace 1N914's with?

i don't think it was the additional 3v that did it, what was the polarity of the DC source you plugged in? this was probably reversed to the TS9 expected.

check the polarized caps, and the transistors. I'm thinking probably the transistors.
Attached Thumbnails
Anyone plug 12v DC ont a TS-9 Tube screamer?-ts.jpg  
Old 1st January 2011
  #4
Gear Head
 

Quote:
Originally Posted by oxide54 View Post
heres a schematic, i presume it wanted 9v dc as it takes batteries


what diodes did you replace 1N914's with?

i don't think it was the additional 3v that did it, what was the polarity of the DC source you plugged in? this was probably reversed to the TS9 expected.

check the polarized caps, and the transistors. I'm thinking probably the transistors.

First of all, I don't think it was the 1N914s that blew, but the power supply protection diode. That being said, I'm surprised that the PS protection diode blew. The 1N914 has a pretty high max forward current. You must have hooked up a PS with a pretty high amperage. But first check that you wired the PS protection diode with the proper polarity. If you reversed it, it would limit the voltage supplied to the active electronics to about 0.8 V, which might cause the (post-repair) symptoms described.

I second the notion of polarity reversal as the main issue.

I'm not sure that a 12V reverse potential would blow the transistors. Most discrete transistors have (relatively) high reverse polarity breakdown voltages and I don't think that anything in the circuit would generate this high of voltage. In addition, the emitter resistor would tend to limit reverse current flow. Also, the fact that the signal chain was still getting something through would tend to indicate that the buffer transistors were still functioning (at least partially).

This leaves the op-amps themselves. That's probably what I'd look at next.

But realistically, the best way to figure out exactly which part of the signal chain the problem is in would be to build a probe that lets you tell where the signal was being killed. The simplest way would be to get a test probe and a alligator clip and wire them to a 1/4" TS plug, which would be plugged into a amplifier. Use a guitar on the input of the unit as a tone generator. If you really wanted to be ghetto about it, just use bare leads coming out of the 1/4" plug to probe with.

Probe at the emitter of the input transistor. If you don't get a signal there, then the input buffer transistor is blown. If so, replace it. Next, probe the output of the distortion-generator op-amp. No signal coming through? It's blown. Replace it. Next check the output of the tone-control op-amp. Same drill. Finally, test the output. Still no sound? Replace the output transistor.

And, for God's sake, do this with a battery in the pedal before you go trying to hook it up to random power supplies again.
Old 2nd January 2011
  #5
Gear Head
 

Thread Starter
OK,


Quote:
you plugged in 12v dc. what was it expecting?
I plugged in a 12v DC power supply and it was expecting 9v DC or a 9v battery. I am unsure of the polarity on the DC adapter but the description on it goes as follows:

Model:AD-121AN
Input: 120VAC
Output:12V DC 1Amp


The visual inspection after I blew it showed that just the Diode (I believe a 1N4002) was cracked open and partially missing thus me not being sure of the type of diode.

PIX


replaced Diode and direction | Flickr - Photo Sharing!

PCB Diode solder points | Flickr - Photo Sharing!

pcb board 1 | Flickr - Photo Sharing!

I went to the electronics shop and they said use any kind of diode, so I threw in a 1N4007 rated a little higher, so why not.

Quote:
Originally Posted by oxide54
heres a schematic, i presume it wanted 9v dc as it takes batteries


what diodes did you replace 1N914's with?
When you say 1N914's, are those any different from the 1N4007 I put in? I suspect that's what was originally in the TS-9


Quote:
First of all, I don't think it was the 1N914s that blew, but the power supply protection diode.
Could that diode I replaced have been the power supply protection diode? Is it common that they explode like that? I would think they would just slap a diode in there to handle whatever you put at it by mistake, and not fail like it did?
It should have been pretty simple: see the broken part, replace the broken part and bam I got it fixed but something else must have happened? Either that or I threw in the wrong part. What else could have been damaged by using the wrong adapter, you would think it would stop at the broken part?

If you don't mind, where is the op-amp section on the PCB?

Thanks
Old 2nd January 2011
  #6
Lives for gear
 

the op-amp is the 8 pin chip.

be carefull, if you want to change it you need to desolder very carefully, not to damage the pcb.

a hakko or weller desoldering station is the correct tool for the job.

if not, I used to use a stanley knife blade to cut the legs of the op-amp before desoldering "manually" obviously you can't re-use the op-amp.

if you do change the op-amp solder a socket in and put the new op-amp in the socket. 2. reasons - you can swap more easily, + you soldering iron never touches the op-amp less likely to cause damage to it.
Old 2nd January 2011
  #7
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Quote:
Originally Posted by nbtech_2001 View Post
It should have been pretty simple: see the broken part, replace the broken part and bam I got it fixed but something else must have happened? Either that or I threw in the wrong part. What else could have been damaged by using the wrong adapter, you would think it would stop at the broken part?
when working on my mixer recently i accidently plugged the power connectors in wrong to one channel, blew an electrolytic cap, and the op-amps.
Old 3rd January 2011
  #8
Lives for gear
 

Hi

Your schematic does not show any of the supply components so is 'incomplete'.
There are 2 ways to implement a 'protection diode' with differing results.
One is to put in SERIES with the supply so if you connect it to DC reversed it will simply not work. This would also be OK if you actually stuck AC into it and it WOULD work but probably hum quite a bit.
This would NOT trash a 1N4002 diode.
The second is to have it REVERSE connected ACROSS the supply so that if you connect a supply backwards the diode conducts as hard as it can and, given a reasonably limited current capability will prevent the reverse voltage being more than about 0.9 Volts which is very unlikely to damage anything. THIS method relies on a series resistor or fuse to blow hopefully before the diode catches fire. This method is often used in small battery gear as it does not 'waste' 0.7 Volts during normal operation.
There is sufficient resistance in series with the transistors to protect them so the more likely part to have failed is the op amp.
Matt S
Old 6th January 2011
  #9
Gear Head
 

Thread Starter
So, it seems like I'm going to be doing some testing first but this op-amp seems like it's kinda the heart of the tube screamer, so if it is the source of the issue than I should be getting the right one I guess, by this schematic what kind is it? and how should I test if it's blown?

TS-9 Schematic
http://www.harpamps.com/schematics/ibnzts9.pdf

Also, a very interesting website (below) explains how "cheap mods" can do amazing things, so as long as I'm inside the Ts-9 I might as well slap in some fun mods or upgraded parts..I'm a DIY person and can accept if I ruin this..in fact I expect it sometimes, it's how I learn..

Ibanez Tube Screamer History

This also explains the "secret" to the tube screamer's success, some really interesting stuff in there.

"Shh, SECRETS"
Tube Screamer®'s Secret - BTE Audio

OXIDE54:
Quote:
when working on my mixer recently i accidently plugged the power connectors in wrong to one channel, blew an electrolytic cap, and the op-amps.
Is a blown cap pretty obvious to see visually or does it need a multimeter to find out?

Quote:
There is sufficient resistance in series with the transistors to protect them so the more likely part to have failed is the op amp.
Matt S 2nd January 2011 11:30 AM
Clearly the diode nearest to the dc input terminal was exploded, so if thing are running in series than the damage should've stopped at the exploded diode, right? I am no electrician, feel free to correct me, but judging by the schematic I posted would you be able to logically assume where els a failure might have occurred? Also If it wasn't the xtra 3V that blew the diode then what was? The DC cord model/info listed in previous post.

Something worth mentioning is that I also still had the 9V battery plugged in whilst plugging in DC..would that matter?
Old 6th January 2011
  #10
Lives for gear
 

you can identify the op-amp by the markings on it.

the schematic doesn't say.

I would be inclined to agree with matt (he has slightly more experience than me btw) and say check the opamp.

can you post a close up picture of the op-amp (in focus) and we can tell you straight away what op-amp it.
Old 6th January 2011
  #11
Lives for gear
 

from what I read there are quite a few models of this pedal with different op-amps.
Old 6th January 2011
  #12
Lives for gear
 

Hi
The schematic above says a 4558 but in reality most would work in that position although a 'low noise' rail to rail type may be slightly better than some.
A low current consumption type would let the battery last longer but then the start of this thread was referring to damage from a PSU.....
Matt S
Old 8th January 2011
  #13
Gear Head
 

Thread Starter
Can I ask how it was assumed to be the op-amp? just curious
Old 8th January 2011
  #14
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Quote:
Originally Posted by nbtech_2001 View Post
Can I ask how it was assumed to be the op-amp? just curious
the schematic. its fairly obviously its an op-amp from the circuit / diagram / symbol

and that i know anyway the pedal uses one,

if you were in the uk i would send you a 4558D I've millions of them
Old 9th January 2011
  #15
Lives for gear
 

Hi
In reply to why is it likely to be the op amp? it is that these will not tolerate any reverse supply (more than about half a Volt) and therer is not much in the way of a 'current limit' so it is likely to fail.
The transistors are used as 'emitter followers' and have quite large value resistors around them and even if reverse bias is supplied they will be happy for at least 10 - 20 mA, probably more. OK they may not act as 'transistors' while this is going on but it won't kill them.
Matt S
Old 9th January 2011
  #16
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whoops I completely mis-read his question.
Old 10th January 2011
  #17
Gear Head
 

Thread Starter
Oxide, no problem. I should've been more specific. I'm on board now with why it could be the op-amp..So I was doing some research and I figured that well, dam, the DC cord I used was 1amp 12V! 1amp is huge for a circuit board of this type right? or no? Or is it confirmed killer that I was using a reverse polarity DC PS based on the info I gave in previous posts?
Old 10th January 2011
  #18
Lives for gear
 

Hi
A 12 volt 1000 Amp unit would not harm the unit as long as it is connected the right way around. This is because the unit will only draw as much current as it needs which in your case will be around 5 milliamps (I can't be bothered to work it out).
A 9 up to 12 Volt REGULATED DC supply capable of 150mA or more will be just fine. I have not noticed many that are lower current than this.
It should be a 'linear' regulated supply (usually moderately heavy as they have a 'proper' mains transformer), not a 'switchmode' as the cheap switchers you get are likely to make noise on your unit.
Matt S
Old 22nd January 2011
  #19
Gear Head
 

Thread Starter
Ok, so update: I went to get some op-amps at the local electronics Store and requested from a list of them I noted based on what I've heard from "Mod Enthusiasts". Well, it seemed as though they were out of of exactly every op-amp type I requested?? Popular? So I ended up just requesting a specific order for a op-amp that was said to be in Analogman's "Silver Mod" a JRC4558D, funny thing though: That particular op-amp (JRC4558D) was already in my TS-9? Reason well whatever..I just waited for the parts.

So the op-amps finally got there and I noticed, when I got home of course, that they were the wrong op-amps (NTE778A)...So I decided I'd check it out and throw them in anyways to see what interesting things I might get out of it..

Op-amps are really hard to get OUT! I used a solder sucker and pulled solder from each pin until I could wiggle the whole IC out. I soldered the new one in and plugged her in to my line 6 and I am really pleased with how things turned out, the dam thing worked! It sounds pretty good too, a nice vintage driven tone. Only thing is anyone ever put a NTE778A Op-amp in a TS-9? I think it's alright..except one thing, when I turn up the Drive Pot I get horrible buzz, is this inherent in the TS-9 or a result of the different op-amp I threw in?


Also, thanks...Your guy's invaluable expertise nailed the issue and saved me a possible extra 100$ for a new guitar pedal.
Old 22nd January 2011
  #20
Lives for gear
 

Little tip : Op amp-removal


If you don't mind losing the old amp , cut the legs and unsolder/remove each leg seperately this way.


or by a de soldering station with vacuum pump.


Tip 2:

Always put a socket in to put in the new op-amp:

1. You don't burn the op-amp soldering it in.
2. You can change it easily in the future..
Old 23rd January 2011
  #21
Gear interested
 

Old 25th January 2011
  #22
Gear Head
 

Thread Starter
Quote:
Originally Posted by oxide54 View Post
Little tip : Op amp-removal


If you don't mind losing the old amp , cut the legs and unsolder/remove each leg seperately this way.


or by a de soldering station with vacuum pump.


Tip 2:

Always put a socket in to put in the new op-amp:

1. You don't burn the op-amp soldering it in.
2. You can change it easily in the future..
Yeah, I was lucky and didn't mess up the IC soldering it in but im actually going to cut that one out and throw in a socket so I can mess around with various op-amps..thanks for the info.

My next step is to clean up some possiblly inherent "noisy" components..get rid of that buzz, I've heard of those mods out there.... but so far I've successfully Fixed and somewhat moded the TS-9...and I'm happy with just that..
Old 25th January 2011
  #23
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Quote:
Originally Posted by nbtech_2001 View Post
My next step is to clean up some possiblly inherent "noisy" components..get rid of that buzz, I've heard of those mods out there.... but so far I've successfully Fixed and somewhat moded the TS-9...and I'm happy with just that..

I completely removed all the buzz/hum from my mixer, star grounding it.
Old 27th January 2011
  #24
Gear Head
 

Thread Starter
Yeah, I've heard of stargrounding before, That involves modifying the common ground right?..That also seems like a really effective way of fixing aground loop buzz for multiple components...but I think the TS-9 is noisy either A.) Because of some inherent noisy parts inside or B.) Because of the new op-amp I threw in it just recently. I could be wrong but anyone shed any light on why the thing is so dam noisy??
Old 27th January 2011
  #25
Lives for gear
 

Hi
If you are using a mains supply on it, is it a 'switchmode' type?
Is it the same noise and buzz if you use a battery?
The different chip you put in may be oscillating at some positions of the gain control.
All things to consider.
Matt S
Old 29th January 2011
  #26
Gear Head
 

Thread Starter
Quote:
Originally Posted by nbtech_2001 View Post
OK,


I plugged in a 12v DC power supply and it was expecting 9v DC or a 9v battery. I am unsure of the polarity on the DC adapter but the description on it goes as follows:

Model:AD-121AN
Input: 120VAC
Output:12V DC 1Amp

I am unsure if the PS is a switchmode type, but above is a description of it. How would I tell? I am only using the included 9v though and I get the buzz. I think you may be correct about the issue with the newly replaced op-amp. Would a multi meter or Oscilloscope tell me if there is "oscillations" in the op amp? I do notice the buzz more when adjusting the gain but it's hard to tell because naturally the gain will increase the buzz anyways, right? thx
Old 29th January 2011
  #27
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Quote:
Originally Posted by nbtech_2001 View Post
I am unsure if the PS is a switchmode type, but above is a description of it. How would I tell? I am only using the included 9v though and I get the buzz. I think you may be correct about the issue with the newly replaced op-amp. Would a multi meter or Oscilloscope tell me if there is "oscillations" in the op amp? I do notice the buzz more when adjusting the gain but it's hard to tell because naturally the gain will increase the buzz anyways, right? thx
you could try bypass caps from the + & - supply lines to op amp to ground.
Old 29th January 2011
  #28
Lives for gear
 

Hi
A switchmode supply will not weigh much but a 12 Volt 1 Amp with a 'real' transformer will be pretty heavy and large.
Matt S
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