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| Beginners Road To Repair |
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| don@cascadefellowship.org:
--- Quote from: Dubbie on June 26, 2018, 01:24:14 am ---Yep. You can see the pinout on page2. Skimreading the datasheets for the various parts will give you lots of info and help you figure out what is doing what on the board. --- End quote --- Ok. So both regulators seem to be input, ground, output (with pins down from left to right). While testing the 7812 with my DMM (black lead on ground) I'm getting 3.4 volts on input and .08 volts on output. On the 7912 I'm getting 16.9 volts on input and 5 volts on output. However, this pinout doesn't jive with the 7912 data sheet which shows ground, input, output (again pins down from left to right). I'm not sure which model the regulator without the printing is. If I'm reading the data sheet on the 7812 correctly, I don't think it's operating up to spec. |
| Old Printer:
By putting the name of the unit into Google it first took me to their website. First thing they said was this is an all analog device, which will make troubleshooting easier. By adding "schematic" to the search phrase I wound up at a site called Freestompboxes where one of their pass-times seems to be hunting down schematics and reverse engineering pedals. You need to join to get complete access, but one poster seemed to have either the factory schematic or had reversed it himself. That would really give you a leg up. It is amazing the info that can be ferreted out with some perseverance. Good luck with your repair, it looks like a pretty straight forward circuit. |
| don@cascadefellowship.org:
Update: After looking at the other voltage regulator (the one that I thought didn't have any writing on it) with a flashlight, I was able to see some printing on it. It's indeed a 7912 regulator. I've got my DMM set to DC and I don't think either regulator is outputting 12 volts. Are they both bad? Am I doing this right? |
| Dubbie:
Ok, so now there are a couple of possibilities, there could be a fault with the power regulators or their supply. OR there could be a short somewhere in the rest of the circuit that is pulling the voltage right down. If would be good if you could identify a way to disconnect the power supply from the rest of the board. That will allow you to see where the problem is. |
| StillTrying:
--- Quote from: don@cascadefellowship.org on June 26, 2018, 02:06:10 am ---Ok. So both regulators seem to be input, ground, output (with pins down from left to right). While testing the 7812 with my DMM (black lead on ground) I'm getting 3.4 volts on input and .08 volts on output. On the 7912 I'm getting 16.9 volts on input and 5 volts on output. However, this pinout doesn't jive with the 7912 data sheet which shows ground, input, output (again pins down from left to right). I'm not sure which model the regulator without the printing is. --- End quote --- Some of your voltage readings seem like you might not have the DMM black on a 0V/gnd. I'd check if the 7812 and 7912 have a pin connected directly together, that will be 0V/gnd and then find which of the 3 pins on the nearby socket is 0V/gnd, and measure ALL voltages from there. |
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