Polida Warning!

[Kinski]

So I think I got a bad/fake batch of 7660S from Polida off eBay.

I built a GE Fuzzrite for a friend. Used the Polida 7660S. Few days later my friend told me it stopped working during a rehearsal. Got the pedal back, put in another 7660S, and was just informed that last night the pedal died again RIGHT before a big gig. I got the pedal back late last night. Sure enough, dead 7660S.

I've been working on the pedal all morning. Basically, I've fried SIX of these 7660S chips with ease. Everything works fine, but if you power and unpower the pedal a few times, usually around the 5-8th time of powering up, the chip becomes scalding hot and dies. Checked my power supply, and its just over 9v. I can even kill the chips with an old 9v battery (reads about 6.5v).

Dropped in a LT1054, and its all working solid now. I'm actually trying to kill this chip by powering and unpowering the pedal over and over and over again. Rock solid.

After much embarrassment and endless apologies, I think its all good now. Basically, I'm gonna abuse this pedal for the next few days to make sure I can't kill it.

I might just stick to LT1054 for all inverter needs from now on. BEWARE!

Also, anyone else ever had this problem?

[Frank_NH]

The LT1054 can take higher current levels than the 1044/7660 chips and they aren't too much more expensive.  That's all I use now unless a circuit specifically calls for a 1044/7660.

[Kinski]

I just dropped in the 1054 in place of the 7660, thats okay to do, right?

On Mon, Nov 9, 2015 at 11:18 AM, Frank_NH [via Guitar FX Layouts] <[hidden email]> wrote:

The LT1054 can take higher current levels than the 1044/7660 chips and they aren't too much more expensive.  That's all I use now unless a circuit specifically calls for a 1044/7660.

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[Kinski]

also, where do you source your 1054?

On Mon, Nov 9, 2015 at 11:28 AM, Taylor Levine <[hidden email]> wrote:

I just dropped in the 1054 in place of the 7660, thats okay to do, right?

On Mon, Nov 9, 2015 at 11:18 AM, Frank_NH [via Guitar FX Layouts] <[hidden email]> wrote:

The LT1054 can take higher current levels than the 1044/7660 chips and they aren't too much more expensive.  That's all I use now unless a circuit specifically calls for a 1044/7660.

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[rocket88]

Bro thanks for the heads up. It seems that this seller went from having good parts to having junk. I had hoped they would start to cleanup their act, but obviously not. Stupid question, did you try a 7660s that you KNOW is good? It's just out of curiosity as to if the chips are crap or if there's some other issue going on. I would think it is the chips since the LT1054 works.

[Chris60601]

See... This is precisely the reason I don't do eBay. Too many unknowns and to much of a hassle to get things corrected.

And, if yer building for folks (as you did) things like this happen and depending on the customer, word if mouth could have an adverse effect on future builds.

I get the fact that you get good deals on eBay, but too much of the unknown for my likes. I know, I know... Many folks swear by eBay, these are just my opinions.

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From: [hidden email]
Sent: ‎11/‎9/‎2015 9:50 AM
To: [hidden email]
Subject: Polida Warning!

So I think I got a bad/fake batch of 7660S from Polida off eBay.

I built a GE Fuzzrite for a friend. Used the Polida 7660S. Few days later my friend told me it stopped working during a rehearsal. Got the pedal back, put in another 7660S, and was just informed that last night the pedal died again RIGHT before a big gig. I got the pedal back late last night. Sure enough, dead 7660S.

I've been working on the pedal all morning. Basically, I've fried SIX of these 7660S chips with ease. Everything works fine, but if you power and unpower the pedal a few times, usually around the 5-8th time of powering up, the chip becomes scalding hot and dies. Checked my power supply, and its just over 9v. I can even kill the chips with an old 9v battery (reads about 6.5v).

Dropped in a LT1054, and its all working solid now. I'm actually trying to kill this chip by powering and unpowering the pedal over and over and over again. Rock solid.

After much embarrassment and endless apologies, I think its all good now. Basically, I'm gonna abuse this pedal for the next few days to make sure I can't kill it.

I might just stick to LT1054 for all inverter needs from now on. BEWARE!

Also, anyone else ever had this problem?

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[Kinski]

Rocket, I don't have another 7660S except this batch, so I can't try any others out. But 1044 and 1054 all work fine, even after much abuse. So I'd think it would have to be the 7660S that are at fault.

Chris, as for eBay, yeah, its sketch, but I didn't know where else to get the 7660S. I rarely, order from eBay, unless I have to. And this is the first time I ever had a problem doing so.

I don't build a ton for people. Mostly for friends if they ask me to. I've never had any of my builds fail on anyone before. So this is a first. But yeah, no more chips from China.

I want to find a good source of 1054 and just load up on those. Anyone know a good place to get them?

[rocket88]

Hmmm. As long as it's working alright that's all that matters. As far as buying from eBay, the thing is to avoid the issues with getting fakes is to look at the prices. You can get good deals, just when the price is too good to be true it is. When you look at polida they're are so cheap that it's not worth the risk.

[Frank_NH]

I get my LT1054 chips from Smallbear Electronics.

And yes you can often sub a LT1054 for a 1044/7660.  Pin 1 of the LT1054 can either be unconnected or connected to your source voltage (9V).

Your case, however, sounds unusual.  If your circuit called for a 1044/7660 charge pump, you should be able to use one - and they shouldn't get hot!  It's possible that the ones you purchased were defective or perhaps not rated for the current you are drawing with the effect.

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Edit:  Could you post the circuit you are using for the fuzzrite?  I realized this requires -9V and not a voltage doubler (where you can often substitute a LT1054).

[Kinski]

Thanks. Not using as a charge pump. Its just inverting + - for the PNP transistors.

On Mon, Nov 9, 2015 at 12:35 PM, Frank_NH [via Guitar FX Layouts] <[hidden email]> wrote:

I get my LT1054 chips from Smallbear Electronics.

And yes you can often sub a LT1054 for a 1044/7660.  Pin 1 of the LT1054 can either be unconnected or connected to your source voltage (9V).

Your case, however, sounds unusual.  If your circuit called for a 1044/7660 charge pump, you should be able to use one - and they shouldn't get hot!  It's possible that the ones you purchased were defective or perhaps not rated for the current you are drawing with the effect.

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[Kinski]

Just saw your edit, asking for the layout (thanks Rocket!).
I used this, along with a small vero for the inverter board.
This is my second one. I build another for myself months ago with an inverter and its never had any problems. I really think its just a bad batch of IC I got from Polida.

[Frank_NH]

If you are using the voltage inverter vero layout from this site, the LT1054 will work fine.  Here is the voltage inverter from the datasheet.



You can up the big cap from 47uF to 100 uF and add the 2 uF cap if you want to be consistent with the datasheet (I would do that). Connecting pins 1 and 8 is fine as I mentioned previously.

[Kinski]

hey thanks. How important is that 2uf?

On Mon, Nov 9, 2015 at 1:01 PM, Frank_NH [via Guitar FX Layouts] <[hidden email]> wrote:

If you are using the voltage inverter vero layout from this site, the LT1054 will work fine.  Here is the voltage inverter from the datasheet.



You can up the big cap from 47uF to 100 uF and add the 2 uF cap if you want to be consistent with the datasheet (I would do that). Connecting pins 1 and 8 is fine as I mentioned previously.

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[Kinski]

Well, I added a 2.2uf cap just for good measure. All is running well.

[Frank_NH]

The 2.2uF cap is likely to help remove noise from the voltage source.  Like chicken soup for a cold, it can't hurt!   

[Muadzin]

I've gotten J201's from Polida in the past. They were all fakes. All of them. I wouldn't trust parts from Polida, or any Chinese eBay seller, not even to make decorative parts. Chromosphere posted some interesting vids on the Madbean forum once about how the Chinese fake industry takes apart old PCB's and harvest them for parts, then refurbishes them for resale as new (if you're lucky) or fakes.

In the end its all about trust. Trust that when you buy something you get what you order. Greed destroys trust as greed doesn't care about establishing trust, only about making a quick buck. Which makes these Chinese fakers a cancer that can destroy their own industry. Unfortunately those Chinese eBay sellers don't seem to care, blinded as they are by greed. But cancer left unchecked ultimately kills the host body, thus the Chinese sellers are laying the seeds of their own destruction.