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| Beginners Road To Repair |
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| don@cascadefellowship.org:
--- Quote from: don@cascadefellowship.org on June 26, 2018, 03:45:06 pm --- --- Quote from: BrianHG on June 26, 2018, 11:37:08 am ---It sounds like his input power rectifier diodes are blown open, or, his AC power switch is open, or, the +12v regulator is shorted to GND, or the power input filter caps are blown to a short (this last one would be unusual without smoke and residue coming out of one of those 21 electrolytic caps). --- End quote --- I'll start learning how to check all of those components in that order and post my results. I can verify that all the components and the boards do not show and burn marks or blow outs. --- End quote --- Checking continuity on the 7812 regulator shows that the ground and the output are shorted together. The ground and the input does not have continuity. On the 7912 both the input to ground and the output to ground do not have continuity. Does that mean I've identified a likely problem in that the 7812 ground and output show continuity? |
| StillTrying:
"Checking continuity on the 7812 regulator shows that the ground and the output are shorted together." If you're sure it's a dead short, for quickness I'd just neatly snip the output leg of the 7812 at the 90 deg. bend myself, to see if the short is the 7812 itself or somewhere on the 12V line. |
| don@cascadefellowship.org:
--- Quote from: StillTrying on June 26, 2018, 04:43:13 pm ---"Checking continuity on the 7812 regulator shows that the ground and the output are shorted together." If you're sure it's a dead short, for quickness I'd just neatly snip the output leg of the 7812 at the 90 deg. bend myself, to see if the short is the 7812 itself or somewhere on the 12V line. --- End quote --- I'm totally not sure of anything! LOL! I popped the 7812 regulator off the board and checked it. The short is not on the regulator but somewhere else on the 12 volt line. How does one go about tracking a 12 volt line looking for a short? Is it a matter of just following the trace of the 12 volt and ground lines to find where they short? |
| don@cascadefellowship.org:
--- Quote from: Old Printer on June 26, 2018, 02:17:13 am ---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. --- End quote --- Here is the schematic I got from the website. |
| CJay:
There are two connectors from the 'regulator' board to the main board, disconnect those and see if the short disappears. I have a suspicion it won't. There are two yellow blobs on the regualtor board near the jack inputs, they're tantalum capacitors, C29 and the other next to the QC sticker. I would be desoldering those if the short doesn't disappear when you unplug the main board. |
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