wrong voltage on my core r4d

MIDIbox SID
1

i finished today to assemble my new core kit bought from smashtv

but when i tryed to check the voltage

instead of 5v

i got 1,66!!!

i tryed to check all the connections

but looks allright

what can i do to solve the problem?

2

what can i do to solve the problem?

You can solve it  ;D …

  • Check all component placements: Is the regualator in the right direction mounted, are all caps ( + / -) correct mounted. Is the rectifier correct placed, …

  • check for solder bridges and double, triple check everything.

  • Measure the voltage that comes from your power supply and then measure the voltage after the rectifier and then the voltage after the regulator.

And please don’t put any IC in his socket before the voltages on the board are right.

What are your measuring results?

greets

Doc

3

so about the components mounted on my board

i just followed the map printed on it, so…if the print is right i did it right

and also the live map that is on the smashtv’s site is pretty clear

i also tryed to check the voltage on another core module bought from mike

and the voltage is 5v

so it’s not a problem with my power supply (i use the original c64 transformer)

i’ll try to measure the after the rectifier and the regulator

in the while

thanx

4

so these are the results

from my psu i i have 5,33 v

i arrive to the rectifier and after that my voltage is 4,20v so is already 1 volt less

after the rectifier i go to the regulator with 4.20v and after the voltage is 1.70v!!!

what happened to my 5,33v???

5

This is normal!

The recitifer “sucks” about 0,7 V and the 78xx needs at least ~ 1,5 Volts over it´s reference voltage to work properly.

This means: 5V + 1,5V + 0,7V = 7,2 V -> You should have at least 7,5 V coming from your PSU.

Greets! :slight_smile:

6

I’ve seen mentions that 9v is the ideal input, it’s what’s working for me anyways…

7

Hi Tokyomatic,

That’s maybe a stupid question I’m asking, I’ve never used the C64 PSU but are you sure you’ve done the connections/mounting in the right way?

My impression is that the C64 PSU has a 5V DC output and a 9V AC output.

I believe that the output you’re using is the 5V one as you read 5.33 volts. I could not explain how a measured 9V AC could become 5.33 volts on the voltmeter.

If you’re indeed using the 5V DC output which makes a lot of sense, then you should not mount the bridge rectifier and the regulator on the Core. You should actually connect your power line to J2 instead of J1.

Maybe give a second look to the following diagram to check your connections and mounting:

http://www.ucapps.de/mbhp/mbhp_4xsid_c64_psu_optimized.pdf

Best regards,

Lall

8

my idea is to use this new core as a master for a sid synth

when i tryed to measure the voltage on the connections for ic1 and ic2

i got 1.70v

so basicly if i use the regulator(on v2 i replaced it with a bridge)

i have to use j2…right

or if i use j1 i have to remove rectifier and regulator?

just to know if i understood…

9

Hi,

J1 is only an input and it can work with both AC and DC. Note that in the case of DC as Pay_c mentionned then you need quite some more voltage at J1 in order to get in the end the 5V you want.

J2 can be or an output or an input.

-> output when the PSU is connected on J1 then you get at J2 the necessary 5V and you can power something else from J2.

-> input when the PSU ( must be a 5V DC one) is connected on J2 and nothing is connected on J1 and the regulator and rectifier bridge are not mounted.

If you use the C64 PSU then the wisest is to use the 5V output to drive directly the J2’s of your cores as depicted in the schematic below:

http://www.ucapps.de/mbhp/mbhp_4xsid_c64_psu_optimized.pdf.

Please take extreme care that there’s no protection against over-voltages on the Core when you power it from J2. So you should not make mistakes with the PSU oterwise you’ll destroy the chips. When using J1, it’s safer because the regulator will do its best to provide only 5V at its output.

Best regards,

J-C

10

so i have to replace the regulator with a bridge

and use j2…perfect…

but from that schematic i also see that now the connection from core to sid j10

is 1:1, on the previous version was different if i’m not wrong

but at the time i was using  a v2 core and sid

i can do that using an r4d core and a v2 sid?

11

ok, i removed the regulator

and i replaced it with a bridge, now i power my core from j2 like on schematics

but what about the rectifier? on my core v2 i have the rectifier

and the voltage is 5,33v

on r4d i checked the pins on ic1 and ic2 sockets

and now i have 4,22v i need at least 1volt more…

are u shure that i also have to remove that rectifier?

i have to replace it with something or i have just to remove it?

thanx guys 4 the help…

12

As long as you don´t put anything on J1 (it´s useless now) you don´t *have* to remove it. The only important part to certainly remove is the regulator.

Greetz! :slight_smile:

13

Hi Tokyomatic,

As pay_c said, there’s no need to remove the rectifier and there’s also no need to have it.

On the other hand, if J1 is left unconnected and the regulator has been unmounted, then there’s absolutely no reason why you should loose ~1V like it’s the case now. So I would advise you to double check everything again to make sure everything’s correct because that loss is pretty strange to me provided that J1 is unconnected and regulator is unmounted of course.

Best regards,

Lall