Defective MN3101's coming out of hong kong

[pezed]

i just received a few of them.. when in the CE-2 circuit pin 8 of the MN3101 should be about .6V
The recent chips i have received have this voltage up at about 8.8volts and this causes the mn3007 to not work correctly!  Not sure why this is happening on these chips now, but the fix i found is to just leave pin 8 of mn3101 lifted (not inserted into the socket!)
just figured i'd warn you guys!

[Toney]

Hongkong superseller/Vermont guitars and a few other names...?
You are not the first!

[Dirk_Hendrik]

Pin 8 is the VGG out which should be 14/15 of VCC. When VCC is 9 volts thant means VGG at pin 8 should be 14/15*9= 8.4 volts. This suggests that your supply voltage was slightly higher than 9 volts.  I'd suggest you recheck your circuit as the problem you have may be solved (surprisingly I must say) with that lifted pin but not in the correct way.

[pezed]

Pin 8 is the VGG out which should be 14/15 of VCC. When VCC is 9 volts thant means VGG at pin 8 should be 14/15*9= 8.4 volts. This suggests that your supply voltage was slightly higher than 9 volts.  I'd suggest you recheck your circuit as the problem you have may be solved (surprisingly I must say) with that lifted pin but not in the correct way.

in the CE-2 circuit the chip polarity is backwards so the input voltage is actually -9
but yes these chips i got from Vermont guitars.
I've built several CE-2s now and i also have a stock boss CE-2 and pin 8 on the mn3101 has always read about .6 volts in this circuit, until i got this latest batch of chips!
I actually got the circuit to work with the defective chip but with a ton of distortion coming from the MN3007 and the bias trimmer basically only had 1 spot that even worked instead of 2/3rds of the trimmer working!  Sounded like a Fuzz Chorus!
but lifting pin8 of the mn3101 and allowing pin4 of the mn3007 to be tied to ground via the 47uf cap seems to work just fine, sounds great with no distortion this way!  just thought i'd post to save others the annoyance i went through debugging the thing for 2 hours before realising it was a problem with the silly clock chip!

[dustbro]

Thanks for the info! I also got my chips from Vermont guitars. I was pulling my hair out trying to make sense of it all. Pulling pin 8 made it work... but does it sound like a proper 3101? It sounds pretty good, just not sure if I should be looking for a new chip cause i dont have anything to compare to.

[anchovie]

I'm bumping this thread because it saved me a lot of frustration with debugging my Tonepad CE-2 clone this evening. I had two MN3101 chips that were Ebay "bargains" - the first one that I tried pulled so much current that smoke came out of the 33 ohm resistor! The second one didn't make anything hot but I had no chorus effect. Finding this thread solved the problem and the circuit is sounding great with pin 8 of the 3101 out of the socket.

Using the forum's search facility is awesome! 

[R.G.]

Don't sweat the MM3101s. There are defective MEDICINES coming out of China and Hong Kong (although probably as a transshipment point).

It seems the clever newly minted MBAs that went to the pharmacy firms figured out that if offshoring was good for making steel, it was good for making interferon, and every other high tech drug as well, so they've been quietly setting carefully (?!) controlled factories for making drugs in low-wage places as well.

I have no doubt that the factories run by the pharma companies turn out the right stuff in carefully controlled conditions. However, once someone of less scruples sees that an oval pill of the right color can be substituted for the real stuff, and that making pills out of compressed chalk dust is easy, the supply chain can be corrupted because, the pharma biz being what it is, that stuff is significantly more valuable than gold by weight, and the only good way to tell what you didn't get is with a mass spectrometer. That's one of the few tools I don't have. Yet. 

I am fortunately unfamiliar with the pharmacy price of viagra and cialis, but I've heard radio ads claiming to save you money by selling you these for as little as $3 a pill, down from the normal pharmacy price they claim of $15 a pill. At those prices, you have to wonder if shaving an aspirin down with a razor blade and using easter-egg dye is far behind. Sounds like a perfect cottage industry.

But I do worry about where the next shipment of chemotherapy stuff comes from for my elderly relatives.

[frequencycentral]

I started an ibanez 301 flanger but i can only find the ics on ebay from hk in quantities of 10.

I saw that auction too, and thought the same thing. I messaged the seller and he set up auctions for two of each chip, so now I'm set for a FL301 and a CE2.

If you have any problems with your Hong Kong chips, read this thread: http://www.diystompboxes.com/smfforum/index.php?topic=59430.0

Thanks for the heads up James! Were yours from hongkongsuperseller? So I should just leave pin 8 with no connection from the word go?

[anchovie]

Mine were from Vermont guitars, who is also mentioned earlier in this thread.

I'd say best to leave pin 8 out of the socket and if it doesn't work try it with it in, seeing as I had a chip cook!

[ampman50]

I've built my second CE-2 and it definitely doesn't sound like the first. The chorus is weak with little depth. I got my chip set from Small Bear and was wondering if I did something wrong. I tried a different MN3101 with no change. The PCB came from Tonepad. I checked all the component values and they seem fine. Could the MN3007 be bad?