power supply

[gzifcak]

hi,
i'm only getting readings of 9.54 and 4.3 at j4 instead of 12 and 5.33. i've checked all the values and polarities a few times and reflowed solder to all the joints. all the other voltage readings in the manual are more or less correct.

thanks for any suggestions,
greg

[gzifcak]

ok,
after testing around again, now i'm getting 12.23 at pin 3, and nothing at pin 1. not zero volts, but the 0.L reading.

?

[gzifcak]

if someone could just give me a couple of readings to check in the power supply circuit i would appreciate it. so far i'm not getting what other people are reporting at the pins of the 6562; there's no 5.33 to be found. does anyone know what i should be getting at previous points in the path?

thanks,
greg

[gzifcak]

i just realized that i'm getting 12.24 volts at pin1, which is supposed to be 5.333, and nothing at pin3, which is supposed to be 12 v.

thanks for any suggestions.

[Jonnay]

Hmm, have you calibrated the voltage at J4 to be 5.333 volts? You do so by adjusting TM6. After that, your 12 Volts should just snap into place. (ideally it will be 11.851V)

[gzifcak]

actually, its my 5.33 pin (1) that reads 12.24. my 12 v reads nothing. the strange thing is, all the parts are in right, i've quadruple checked and reheated all the solder joints, and all the tests in the power supply work out except for the ones for j4. ??

now, i don't read anything anywhere between the - side of c5 and ic23. this can't be right. c5 has the right voltage reading across it though. ??

thanks,
greg

[Jonnay]

Well, on the power supply, the 5.333 V and 12V supplies are linked. Unless you have the 5.333 properly calibrated, the 12V won't work at all.

The - side of C5 wont lead to IC23 It just goes into the 1N4001 diodes, and then to the power jack. I would check out the following:

R3 is 68Kohm, D45 through D47 are in properly, R4 is 5.6k ohm, and R5 is 2.4k ohm. Have you tried adjusting TM6?

[Guest]

yes, all of those check out, except i think r3 is 6.8k right? or is the manual wrong? i have adjusted the trimmer, to no avail.

what i mean about c5 is that if you look at the schematic, i am getting no voltage readings at any point between the junction of the + side of c5 and ic23. it appears to me that i should be getting some positive reading, that is then reduced to 5.33 at the + input of ic23 (pin 5). there is currently no voltage reference for the trimmer present at the input of ic22.

thanks for your suggestions. anything else that pops out at you?

[gzifcak]

oops,
that was me.

[gzifcak]

ok,
now it's gone up to 16 or 17 volts at pin 1 of j4, and the heatsink is getting hot. hmmm. now i'm kind of afraid to plug it back in for fear of ruining the 7805. i just built the VCO in the meantime, but i obviously can't test it.

thanks for any suggestions.

[LysergicBassLine]

Hi,
is your power adapter 9V AC ?


http://www.ladyada.net/forums/viewtopic.php?t=545&highlight=

[gzifcak]

now its back to 12.24 and the 7805 is cool.

could someone verify the voltage readings around c8, r1, r2 and r3 for me?

i'm getting 12 v at pin 5 of ic23, but nothing at pin 8. ??

[Guest]

yeah, my adapter puts out 9vac. all the test points in the fab manual up to j4 match great.

any other suggestions?

thanks,
greg

[gzifcak]

me again, duh.