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 Mystery chip in CE-2		  New Topic  Reply to Topic
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walrus121
Silver Member

USA
187 Posts
Posted - 10/16/2005 :  17:31:10  Show Profile  Send walrus121 an AOL message  Send walrus121 an ICQ Message  Click to see walrus121's MSN Messenger address  Send walrus121 a Yahoo! Message  Reply with Quote
I don't know if anybody else sees this in their pedal, but my MIT CE-2 has a capacitor glued to the top of a 8-pin DIP IC in the top left corner of the PC board. I don't particularly feel inclined to remove this capacitor from it's place, so I was wondering if anyone out there knew what is in this IC.

lightburst
Silver Member

Germany
158 Posts
Posted - 10/16/2005 :  18:24:29  Show Profile  Visit lightburst's Homepage  Reply with Quote
It�s a TL022CP.
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walrus121
Silver Member

USA
187 Posts
Posted - 10/16/2005 :  20:16:12  Show Profile  Send walrus121 an AOL message  Send walrus121 an ICQ Message  Click to see walrus121's MSN Messenger address  Send walrus121 a Yahoo! Message  Reply with Quote
Good, then I will probably want to remove it.
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lightburst
Silver Member

Germany
158 Posts
Posted - 10/17/2005 :  09:58:03  Show Profile  Visit lightburst's Homepage  Reply with Quote
Why?

It�s only the op-amp for the oszillator and is in no way connected to the signal path. So it should have no influence to the sound exept for the sweep characteristics of the chorus modulation.
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walrus121
Silver Member

USA
187 Posts
Posted - 10/17/2005 :  18:23:48  Show Profile  Send walrus121 an AOL message  Send walrus121 an ICQ Message  Click to see walrus121's MSN Messenger address  Send walrus121 a Yahoo! Message  Reply with Quote
Yeah, you might be right. I think I really do have to replace the TL022s in my GE-7 though; I replaced the JRC4558D with an LM833N, still noisy, and they are the only things left that I can see that would still make so much noise. The noise only happens when at least one of the band sliders is moved from the center position, too. What do you think?
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walrus121
Silver Member

USA
187 Posts
Posted - 10/17/2005 :  18:30:34  Show Profile  Send walrus121 an AOL message  Send walrus121 an ICQ Message  Click to see walrus121's MSN Messenger address  Send walrus121 a Yahoo! Message  Reply with Quote
Actually, FYI, often is the case in electronics when low-quality parts cost more than higher-quality parts. The TL022 is expensive now compared to even HI-FI op amps. This is because demand is higher for better op amps meaning that the supply is higher and the opportunity cost is lower, therefore lowering the sale price. Quick lesson in electronics and economics intersecting.
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lightburst
Silver Member

Germany
158 Posts
Posted - 10/17/2005 :  18:42:50  Show Profile  Visit lightburst's Homepage  Reply with Quote
In case of the GE-7 I suggest changing the TL022s is a good idea.
I�ve changed a Tl072 in a Marshall Guvnor (first version) with a Burr Brown OPA2134PA and the sound became more transparent and dynamic. I think, in an equalizer it should be even more important wich op-amp is used

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walrus121
Silver Member

USA
187 Posts
Posted - 10/17/2005 :  23:42:58  Show Profile  Send walrus121 an AOL message  Send walrus121 an ICQ Message  Click to see walrus121's MSN Messenger address  Send walrus121 a Yahoo! Message  Reply with Quote
Wow, there is a TL072 in my amp, too. And it is very noisy in drive mode. Guess that will have to go. Thanks for the tip.
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walrus121
Silver Member

USA
187 Posts
Posted - 10/18/2005 :  00:05:41  Show Profile  Send walrus121 an AOL message  Send walrus121 an ICQ Message  Click to see walrus121's MSN Messenger address  Send walrus121 a Yahoo! Message  Reply with Quote
Oh yeah, what made you think to use an OPA2134 as opposed to any other op amp?
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lightburst
Silver Member

Germany
158 Posts
Posted - 10/18/2005 :  08:38:15  Show Profile  Visit lightburst's Homepage  Reply with Quote
I found this hint on Fuzz Central in the instructions for modifying the SD-1. I already knew the OPA as an op-amp specialy made for musical applications. A little later I found modification instrucitons for the Fender HotRod Deluxe wich called for changing the reverb driver op-amp (a TL072) with another Burr Brown. So I decided to give that chip a chance in my Guvnor.
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walrus121
Silver Member

USA
187 Posts
Posted - 10/18/2005 :  17:08:50  Show Profile  Send walrus121 an AOL message  Send walrus121 an ICQ Message  Click to see walrus121's MSN Messenger address  Send walrus121 a Yahoo! Message  Reply with Quote
Yeah, my amp is a Hot Rod Deluxe. The TL072 is used in both the reverb channel and the effects loop. I've already got it opened up, so I will replace them both.
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walrus121
Silver Member

USA
187 Posts
Posted - 10/18/2005 :  17:33:04  Show Profile  Send walrus121 an AOL message  Send walrus121 an ICQ Message  Click to see walrus121's MSN Messenger address  Send walrus121 a Yahoo! Message  Reply with Quote
FYI, Burr-Brown merged with Texas Instruments.
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lightburst
Silver Member

Germany
158 Posts
Posted - 10/19/2005 :  09:40:16  Show Profile  Visit lightburst's Homepage  Reply with Quote
Good to know - thanks!
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walrus121
Silver Member

USA
187 Posts
Posted - 11/06/2005 :  18:23:53  Show Profile  Send walrus121 an AOL message  Send walrus121 an ICQ Message  Click to see walrus121's MSN Messenger address  Send walrus121 a Yahoo! Message  Reply with Quote
OK, I replaced the TL022s in my GE-7 with LM833Ns. Something that I realized though was that in the input impedance of the LM833N is different than the TL022, it might affect the peak frequencies of the bands. It does seem to work, though. I also bought NJM5532As, which I originially was going to put in there, might still do, but I plan on testing both the 5532As and the LM833Ns in my BF-2 and CE-2, substituting for the JRC4558Ds in there.
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lightburst
Silver Member

Germany
158 Posts
Posted - 11/06/2005 :  20:14:49  Show Profile  Visit lightburst's Homepage  Reply with Quote
I would like to hear about the results. So pleas let us know if you�ve done so
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walrus121
Silver Member

USA
187 Posts
Posted - 01/04/2006 :  18:28:27  Show Profile  Send walrus121 an AOL message  Send walrus121 an ICQ Message  Click to see walrus121's MSN Messenger address  Send walrus121 a Yahoo! Message  Reply with Quote
Right now I'm more concerned with finding rubber grommets to fill in the thumbscrew holes, but I was looking to order some Burr-Brown op amps and I can no longer find the website that mentioned the part for the Fender Hot Rod series mod. My computer took a nose dive, so any information from my orders saved on there as cookies for my electronics suppliers is probably gone. I'm disappointed.
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