burned MAXX1044

[harrisxr650]

hey guys i'm running i weird problem on my boneyard V1. The maxx1044 i used for the charge pump gets burned after 4-5 hours of playing i've change 2 of them the last week, i checked the pcb for shorts and its ok, i checked for power to groud continuity and its ok aswell. Is there anything else i should check, is there any logic that the problem is caused the  daisy chain 1spot along with an wah and a second drive i use ( i mean plugging unplugging while the pedal is on cause today it went off after i unplugged my wah while the boneyard was on)? or is the maxx1044 so fragile that catn handle the 9.46v the one spot gives and should i change it to an LT1054 maybe?
thanks

[Scruffie]

The MAX1044 has a 10v maximum input voltage... if you're one spot is steady at 9.4v it should be okay but switching to a TC1044 might help if there's spikes in voltage for some reason, can handle 12V.

A series resistor with the power might help too.

[harrisxr650]

i was thinking too about the 10v maxx can handle and the spikes in voltage, but i wasn't sure, i mean i've seen my 1spot to 9.8v as well ,but arent those regulated? i mean it should deliver around 9.3 to 9,4 but i've seen in mine a 9,8v and maybe its to close to overheat the maxx and burn it, forgive me if i'm thinking wrong or my questions are noobish, i'm trying to learn as much as i can 
thanks

[Scruffie]

R.G Keen would be the man to ask on the subject of one spots, if you've seen it vary though then yeah probably just frying the chip.

As I said, series resistor or higher max voltage chip.

[harrisxr650]

thanks but because i'm noob how do i wire the resistor? in series with v+? and how much resistance? enough to make sure it doesnt pass 9.5v e.x?
thanks

[Scruffie]

100R is probably enough, just stick it in between where 9V comes in from your jack to the board, or actually, even better, you can use a 1N400X (1,2 whatever) diode in series with the supply for a 0.6v drop and also the added benefit of polarity protection (don't know if that's already on board).

[harrisxr650]

its allready has a protection diode but not in line, i will try the resistor right now since i cant find a tc1044
thanks

[midwayfair]

its allready has a protection diode but not in line, i will try the resistor right now since i cant find a tc1044
thanks

Is your "protection diode" a 9.1V Zener or a 1N4001? I can't find the V1 PDF, but if it's a Zener like in the current version and you were seeing more than 9.1V, something was wrong with your diode.

Scruffie's suggestion is for ACTUAL polarity protection with a power supply. The 4001 to ground only works with a battery, and only for a short time. It will blow almost instantaneously with reversed polarity from a power supply. You can use a 1N5817 in series for a lower voltage drop (.2v instead). But the 100R current limiting resistor is much more important.

Mouser carries the TC1044SPCA and 7660 and, even better, the 1054, which can handle up to 15V of input, and can also supply higher current. The cost isn't that much higher and it's a better charge pump that can be used everywhere. Just lift pin 1 in PCBs designed for the 1044.

[Chi_Boy]

Regarding the LT1054, have you ever experience power supply whine?   I know there are notes in the data sheet that show how to add a small cap to increase the operating frequency, but I haven't tried it yet.  Have plans to in the near future though.

[harrisxr650]

its a 1N4001 connected to ground. I've ordered today some tc1044 and some lt1054 ( leaning towards the second to be more safe), but i was wondering why this thing it gets fried all the time, pcb is ok no shorts or anything and it didnt seems to overheat, at least when i touch it seems cold enough, is it possible to have voltage spices when i disconnect another effect from the daisy chain so high to stress the MAX to its limits? Is it safe to put a diode in line and live the 4001 in place or i have to remove it? also if using a 1n5817 as you suggest would i still have to use the 100R resistor or just the diode? btw i've tried anothe max today and while i had the boneyard off and the wah on i disconected the wah and the thing went boom again...
will check the pcb again just to make sure its ok and post back

[harrisxr650]

Regarding the LT1054, have you ever experience power supply whine?   I know there are notes in the data sheet that show how to add a small cap to increase the operating frequency, but I haven't tried it yet.  Have plans to in the near future though.

i've build for a friend one like 1 year ago using an LT1054 i had back then and didnt had any whine issues, i had in mine when i tested using a max1044 it but it turned out a broken solder in the MAX1044, note that i have build 5 of them for some friends and while using 1spot or battery there wasnt any issues when i try it with a power all and some other el cheapo psu i had whine issues, also some whine can be produced if not using shielded wires to input and output of effect as many have experienced here.

[Scruffie]

The LT1054 has a boost, the cap is just for tuning it if it happens to interact.

I wouldn't use a 1N5817 in this application, the whole point of the 1N4001/2 is it'll drop 0.6v giving your 1044 a bit of extra voltage leeway.

Cheapo power supplies can cause whine by messing with the charge pump switching frequencies.

Do this on the input of your pedal if you use a MAX1044 9V>>>100R>>>a1N4002k>>>9VPad it'll drop off a minimum of 0.6v at all times from your supply, hopefully saving your pedal from any minor spikes or supplies above 9.6v.

[nf]

hello, I found this thread looking for a solution for a build I made of a Klon Centaur clone following Harald Sabro's build (https://www.sabrotone.com/?p=729). Well the pedal kinda does not work and in my investigation one of the first things I found is that I am getting half of the inverted input voltage (instead of pretty much the same voltage) from the IC.
i.e.: with an input voltage of +9v, the IC output on pin 5 is ~ -4.5v instead of -9v.
I have swapped the IC with different ones of the same serie. with 1066s even ... has anybody encountered a similar situation or can shed some light on what is happening..?
thank you