# QSI on DC questions



## David Buckingham (Jan 2, 2008)

Hi Folks

I have a Bachmann 2-6-6-2 fitted with a QSI sound system/DCC controller running on DC.

It is uncontrolable

At 8 volts sound starts fine Loco just starts to move at 10.5 volts and then in the next 1/2 volt
it gallop away much to fast.

A man who knows DCC has managed to tame it a bit and cut out the Inertia which helped

The main trouble is the very small voltage change from stop to full speed.

It is so sensitive to voltage it can stop or gallop due to voltage variations in the track and
I am indoors!!

Any suggestions how to spread the voltage so I can get good contol Remember this is DC
but I can get the programming done.

Many thanks Dave


----------



## Greg Elmassian (Jan 3, 2008)

There is definitely something wrong here. Turning off the "inertia" should have exactly the opposite effect. 

Actually, it should start at much less than 10.5 volts. What I think happened is it did have a fair amount of "momentum" set as default. You did not see any motion and cranked the throttle. As the momentum setting allowed the motor to go faster, you now had the throttle open, and it took off. 

Anyway, that is my guess. 

We can proceed no matter what the momentum setting (CV3 and CV4 are set to). 

Put a voltmeter on the track, and make sure you are NOT using any kind of pulse power or PWM power (please give make and model of your power setup) 

SLOWLY increase the voltage until the loco just starts to move. This means turn up the voltage until the sounds start, measure the voltage, and then SLOWLY increase it and wait a bit and increase again. AS SOON as you hear a chuff, stop increasing the voltage and read it, and report back here. 

You might also remove the QSI and test your 2-6-6-2 for starting voltage and operation. I'm thinking there is something wrong with the loco, not the QSI. 

Regards, Greg


----------



## David Buckingham (Jan 2, 2008)

Hi Greg 
Many thanks 
It is 0700 here 

Power supplies as far as I know pure DC using first LGB Jumbo with inertia turned off 

second used 5amp LGB controller direct control 

third Labority power supple very fine control all DC as far as I know. 

Loco works fine without QSI several volts spread over the speed control 

Very slow increases in voltages have been tried with the same results it is a little better now some parameters have been tweeked. 

Loco is with the supplier of QSI in this country (UK) he is trying to fix but has never had on do this. 
e 
We are wondering if the main Bachman board is wrong so will be trying anther loco to see. 

Dave


----------



## Greg Elmassian (Jan 3, 2008)

Very weird. 

I gather you do not have the programmer yourself. It would probably make short work of this problem. I have about 20 QSI's and never had this problem. 

1. I would get the firmware version that was used in the decoder. 
2. It would be nice to know the soundset he loaded in the decoder 
3. Have him try turning BEMF off first. 
4. I would verify the start voltage in CV2, the default value is usually 8, but some locos need very different settings. 
5. Leave some momentum in the unit, CV3 = 10 and CV4 = 5. (CV3 is acceleration momentum) 
6. Try running it on DCC and see if it behaves. 

There is a part in the manual (and reproduced on my site) on tips for the QSI, and the initial "tuning" of CV2, step by step... It's under the power/electronics section... 

Regards, Greg


----------

