# Frequency Central MicroBus PCB Help **URL:** \ **Category:** DIY STUFF\ **Created:** [February 18, 2022, 6:24pm UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671 "2022-02-18T18:24:34Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![unexpectedbowtie](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/unexpectedbowtie/32/10648_2.png) [@unexpectedbowtie](https://lookmumnocomputer.discourse.group/u/unexpectedbowtie)\ **Post date:** [February 18, 2022, 6:24pm UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/1 "2022-02-18T18:24:34Z")
Another tale of woe. I’ve built the Frequency Central MicroBus. The wall supply I am using is 12v AC. 1000ma. I’ve tried two different ones, but only the 12v- LED lights up. Neither the 5V or the 12v+ LEDs light up. I’ve quadruple checked and the regulators are in the right place. Does anybody have any bright ideas before I smash everything up and vow never to do any other DIY projects ever again? 😃 p.s. the 1k LED resistors are installed on the bottom of the board, as I previously had the wrong resistor values in there, so had to replace them. ![photo_2022-02-18 18.23.19](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/5/c/5c1821b1a14b9e0143352d1cf0c4e515bf7ae8c1.jpeg) ![photo_2022-02-18 18.23.21](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/5/e/5eaf5a8a44001f974699e94bee09ed046df4504f.jpeg) ![photo_2022-02-18 18.23.23](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/9/9/995775cad42c7873baacb388dd1fb43adc7c09ce.jpeg) ---
**Author:** ![eric](https://avatars.discourse-cdn.com/v4/letter/e/898d66/32.png) [@eric](https://lookmumnocomputer.discourse.group/u/eric)\ **Post date:** [February 18, 2022, 6:28pm UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/2 "2022-02-18T18:28:15Z")
Are the diode on the input the right way around ? (they are not visible on the pictures) ---
**Author:** ![unexpectedbowtie](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/unexpectedbowtie/32/10648_2.png) [@unexpectedbowtie](https://lookmumnocomputer.discourse.group/u/unexpectedbowtie)\ **Post date:** [February 18, 2022, 6:31pm UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/3 "2022-02-18T18:31:00Z")
I think so, yeah… ![photo_2022-02-18 18.30.50](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/4/6/460317c046d128de00b2148e69b4d8ea7f8e458a.jpeg) ---
**Author:** ![eric](https://avatars.discourse-cdn.com/v4/letter/e/898d66/32.png) [@eric](https://lookmumnocomputer.discourse.group/u/eric)\ **Post date:** [February 18, 2022, 6:36pm UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/4 "2022-02-18T18:36:06Z")
Then I… don’t know ☹ Take your voltmeter, put one probe on “ground” and follow the traces on the PCB with the other probe to see where it stops… ---
**Author:** ![analogoutput](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/analogoutput/32/29663_2.png) [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)\ **Post date:** [February 18, 2022, 6:54pm UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/5 "2022-02-18T18:54:48Z")
You’ve checked the LED orientation? (Simple things first.) Have you directly measured the ±12 V outputs? ---
**Author:** ![unexpectedbowtie](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/unexpectedbowtie/32/10648_2.png) [@unexpectedbowtie](https://lookmumnocomputer.discourse.group/u/unexpectedbowtie)\ **Post date:** [February 18, 2022, 9:17pm UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/6 "2022-02-18T21:17:49Z")
LED orientation all good, yeah! Short leg = cathode = negative = square pad. I just built a second one of these I had, testing every component with one of those component checker things, and triple checking every bit of the PCB… carefully soldering, and same issue on this one! o\_O ![photo_2022-02-18 21.15.07](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/8/1/81bb0f518a9fd5cc6633b6a7737b54a893555a91.jpeg) ![photo_2022-02-18 21.15.11](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/e/e/ee5a05211140bc55c1d26c9de18c3f6d9fc3f6d7.jpeg) ![photo_2022-02-18 21.15.12](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/5/5/5587467f01b83fc6ebcc8701085d0e6950773955.jpeg) ![photo_2022-02-18 21.15.05](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/3X/b/7/b757ff4db89ed47bdb593ffc7f64f330338923c4.jpeg) > [@analogoutput](#): > > Have you directly measured the ±12 V outputs? I must admit ignorance on how to do this. I have a multimeter, so I presume I would connect up the two pins from one of the header connectors to confirm? Any tips there greatly welcomed, as I am a multimeter n00b. ---
**Author:** ![unexpectedbowtie](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/unexpectedbowtie/32/10648_2.png) [@unexpectedbowtie](https://lookmumnocomputer.discourse.group/u/unexpectedbowtie)\ **Post date:** [February 18, 2022, 9:42pm UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/7 "2022-02-18T21:42:03Z")
Found the pins to confirm with the multi-meter, and I’m getting -12v at the expected place, but no voltage reading at either the +5v or +12v pins. The only thing I can think of is that maybe one of the batch of Regulators is fried? but I’m not sure which one that would be. ---
**Author:** ![unexpectedbowtie](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/unexpectedbowtie/32/10648_2.png) [@unexpectedbowtie](https://lookmumnocomputer.discourse.group/u/unexpectedbowtie)\ **Post date:** [February 18, 2022, 9:46pm UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/8 "2022-02-18T21:46:26Z")
Ah, you know what. I bet the power supply I’ve been sent is DC output. The ones I bought were advertised as AC output, but it might not actually be. I’ll try source a reputable AC plug and confirm. ---
**Author:** ![Sonosus](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/sonosus/32/13679_2.png) [@Sonosus](https://lookmumnocomputer.discourse.group/u/Sonosus)\ **Post date:** [February 18, 2022, 9:48pm UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/9 "2022-02-18T21:48:41Z")
It would either be the LM7812 or LM7805 (without looking at the schematic I can’t tell if the 7805 is downstream from the 7812 or has its own capacitors), otherwise there has to be a problem with one of the diodes on the positive rail. Are you sure the ‘component checker thing’ is measuring the diodes properly? I’d imagine so seeing as your capacitors haven’t exploded. Do you have an oscilloscope or access to one? You could use it to check if the power supply is actually putting out 12AC and it isn’t mislabeled. Where did you get it from? ---
**Author:** ![unexpectedbowtie](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/unexpectedbowtie/32/10648_2.png) [@unexpectedbowtie](https://lookmumnocomputer.discourse.group/u/unexpectedbowtie)\ **Post date:** [February 18, 2022, 9:58pm UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/10 "2022-02-18T21:58:44Z")
Thanks for the help and tips 🙂 > [@Sonosus](#): > > Are you sure the ‘component checker thing’ is measuring the diodes properly? I’d imagine so seeing as your capacitors haven’t exploded. I can’t be sure. Would there be a better way to check? I do have a scope, but my knowledge in how to use it is errr… limited beyond for audio. > [@Sonosus](#): > > Where did you get it from? I got the plug from eBay. It was advertised as AC 12V 1A adaptor (no reference to DC). On the actual plug it doesn’t reference DC either, but I should have noticed that it has a polarity, which would obviously mean that it isn’t AC. That’s my own fault. Eugh. Sorry, what a dumb mistake! ---
**Author:** ![Farabide](https://avatars.discourse-cdn.com/v4/letter/f/ecc23a/32.png) [@Farabide](https://lookmumnocomputer.discourse.group/u/Farabide)\ **Post date:** [February 18, 2022, 10:17pm UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/11 "2022-02-18T22:17:38Z")
My only issues with the FC boards is I found the barrel connection to have quite a large footprint and took a lot of heat to flow a reliable solder joint. Barring that get the flux out and lather the b. Board ---
**Author:** ![analogoutput](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/analogoutput/32/29663_2.png) [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)\ **Post date:** [February 18, 2022, 10:48pm UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/12 "2022-02-18T22:48:28Z")
> [@How to use a Multi-meter](https://lookmumnocomputer.discourse.group/t/how-to-use-a-multi-meter/852): > > Made a video explaining how to use a multi-meter for both continuity testing and voltage measurement. We have seen a few questions about this before, so i figured why not make a video. [[How to use a Multi-meter] ](https://www.youtube.com/watch?v=kYlt238MYW0) ---
**Author:** ![CTorp](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/ctorp/32/15023_2.png) [@CTorp](https://lookmumnocomputer.discourse.group/u/CTorp)\ **Post date:** [February 18, 2022, 11:20pm UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/13 "2022-02-18T23:20:22Z")
I bet you your warts are DC. That is exactly what happens when u plug a dc wart in! (Been there done that) ---
**Author:** ![unexpectedbowtie](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/unexpectedbowtie/32/10648_2.png) [@unexpectedbowtie](https://lookmumnocomputer.discourse.group/u/unexpectedbowtie)\ **Post date:** [February 19, 2022, 2:01am UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/14 "2022-02-19T02:01:11Z")
The worst part is that that is the one thing I was completely sure wouldn’t be the case, as I had double checked it. Clearly I am a muppet! ---
**Author:** ![Farabide](https://avatars.discourse-cdn.com/v4/letter/f/ecc23a/32.png) [@Farabide](https://lookmumnocomputer.discourse.group/u/Farabide)\ **Post date:** [February 19, 2022, 3:29am UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/15 "2022-02-19T03:29:20Z")
No muppetry. We’re all on the same journey. ---
**Author:** ![analogoutput](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/analogoutput/32/29663_2.png) [@analogoutput](https://lookmumnocomputer.discourse.group/u/analogoutput)\ **Post date:** [February 19, 2022, 2:55pm UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/16 "2022-02-19T14:55:49Z")
(Happy anniversary! Two years!) ---
**Author:** ![Farabide](https://avatars.discourse-cdn.com/v4/letter/f/ecc23a/32.png) [@Farabide](https://lookmumnocomputer.discourse.group/u/Farabide)\ **Post date:** [February 19, 2022, 4:53pm UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/17 "2022-02-19T16:53:19Z")
What’s two years in @Dud cases? Do we have a Kosmo case metric yet? ---
**Author:** ![Dud](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/dud/32/610_2.png) [@Dud](https://lookmumnocomputer.discourse.group/u/Dud)\ **Post date:** [February 19, 2022, 6:42pm UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/18 "2022-02-19T18:42:29Z")
Yes happy little cake @Farabide , mine is coming in a few days ! 25 feb 2020 my first pic posted : [2 cases 36 modules](https://lookmumnocomputer.discourse.group/t/kosmo-setup-pics/294/32) and the last one (nov 2021) : [5 cases with 90 modules](https://lookmumnocomputer.discourse.group/t/kosmo-setup-pics/294/403) so 2 years = 54 modules 😁 near of 2.25 modules by week 🤣 ---
**Author:** ![eric](https://avatars.discourse-cdn.com/v4/letter/e/898d66/32.png) [@eric](https://lookmumnocomputer.discourse.group/u/eric)\ **Post date:** [February 19, 2022, 7:51pm UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/19 "2022-02-19T19:51:04Z")
> [@Dud](#): > > so 2 years = 54 modules 😁 > > near of 2.25 modules by week 🤣 You did skip math classes, aren’t you ? 😛 ---
**Author:** ![Dud](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/dud/32/610_2.png) [@Dud](https://lookmumnocomputer.discourse.group/u/Dud)\ **Post date:** [February 19, 2022, 9:53pm UTC](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671/20 "2022-02-19T21:53:30Z")
Yes ! math and me = 2 euuuh i forgot something, maybe more by month so 0.5625 modules by week 😉 [Next page](https://lookmumnocomputer.discourse.group/t/frequency-central-microbus-pcb-help/4671.md?page=2)