Hot voltage regulator

[Jorge]

Hello again,

it seems like I'm making 2 steps forwards then 1 step back at the moment.

As far as I can tell everything is fine re. mios,sid app etc, I get all the correct data on the lcd screen on boot up eg.

mios v1.7 copyright T. Klose  then quick flash showing the sid app is loaded then the channel no. and sid number and default patch.

How do I switch on the slaves without having the control surface so i can test them? I sent the sysx command to open the link and burnt mios and the sid app to the slaves. I'm assuming it all went well as Serge's loader sent and received comfirmation .

Any way now  I'm having trouble with my power supply , the voltage reg gets very hot to the point that the thermal overload protection cuts in and shuts every thing down.

No problem with the 12v supply though.

Without the lcd display attached the voltage reg stays hot but dosn't cut out.

My power supply is a self built one based on the improved c64 design, eg dual 9v flat transformer rated at 1 amp output each,

from that I derive the 5v output and a 14v output as in TK's improved design.

the 5v reg has a small clip on heat sink would a larger one help?

Also when I finish the control suface will that draw much current  and so add to the problem?

Any thoughts on including a small fan blowing over the V reg, would that impart noise in the audio signal?

Any help or ideas would be appreciated.

    Thanks    Jorge......

[TK.]

Hi Jorge,

there is no other way to enable the link without control surface, you already made it correctly by sending the sysex string.

Power supply issues: maybe 9V is too much (did you measure the effective voltage at the 7805 input? It could be more than 9V) - a larger head sink can help, another solution is the use of a second converter stage - means: use a 7809 to reduce the voltage to 9V (I still assume that your transformer delivers a higher voltage), then the 7805 to reduce it again to 5V. Thats no professional, but a simple solution.

Best Regards, Thorsten.

[Jorge]

You were right Thorsten,

at the input of the V reg after the bridge rectifier I have a reading of 14.5V,

before the bridge rectifier I have a reading of 10Vac.

I'm using a 18VA transformer tapped to give two supposed 9V outputs at 1A.

I can understand the slight difference in volts AC as a 9V regulator would be able to handle the 1Vac difference.

The 14.5V reading is I assume because of a feedback loop in the signal path due to the mixing of 5Vdc with 9Vac, that is strange as

I mentioned earlier the 10Vac output of the transformer especially as after the 9V  V reg I have a steady output of 14Vdc.

Oh well back to eagle and tweak the power supply board and separate the signal paths, I hope the feedback loop isn't anything to do with the transformer being a dual supply.

I'm learning just as much trouble shooting as I am in constructing the Multi SID, it's all a good learning curve...

Cheers    Jorge.....