| Author |
 Topic  |
|
Disco Stu
Silver Member
USA
303 Posts |
 Posted - 10/02/2008 : 01:12:09
|
| By the way, I would like to post pictures but I can't do that. I tried over in the "test" area of the forum but each time the upload timed out on me. If anyone wants to post a photo, I can send as an email attachment. |
 |
|
|
Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 10/02/2008 : 01:32:45
|
| The timeout is almost always because the file is too big. Keep it under 200k and it should be fine. |
|
|
|
Laurie
Double Platinum Member
Canada
4854 Posts |
Posted - 10/02/2008 : 05:17:32
|
quote:
Originally posted by Disco Stu
With battery attached, lead in jack and LED on, measuring across R54 read "-12.32" and each time I measured across R54 the LED went out.
R58 read 16.46 regardless of probe orientation.
R67 read 8.53 either way.
I got the same values whether I put the probes on the wires/solder joints on the bottom side of the PCB board or on the uninsulated part of the wires coming from the resistor on the top side of the PCB board
I measured D3 both with a brand new battery, and Boss ACA120G power transformer, without a battery attached.
With the battery I read 7.82 Volts. With the power supply I read 8.0 Volts.
That's all the data that I have for now.
Cheers!
OK... I'm guessing you used the "ohms" scale to measure the resistors when the power was on? That's something we would recommend to not do  . When the power is on, please only ever measure "volts".
The main measurement of interest here is D3. It is OK with a reading of 8V, and by inference R54 is OK.
We are kinda stuck now - the next thing I would do if it was on my bench is check the clock signal at CP1, then inject a signal and look at the inputs and outputs of IC3 with a scope to make sure it is OK.
Let me think on where to next with just a volt meter... or if anyone else has a strategy, please jump in!
|
|
|
|
Disco Stu
Silver Member
USA
303 Posts |
Posted - 10/02/2008 : 06:30:06
|
OOPS !
Yes, I measured the resistor value with the power applied, using the Ohms scale of the meter. Like I said, I'm no electrical engineer. But I thought it intersting that all three 22K resistors gave different values -- I suppose that is due to the components adjacent.
Another interesting thing -- the Boss ACA 120-G adaptor puts out 13 Volts, although the label claims "DC 9V 250 mA". I guess the thing to do is never run out of 9V batteries and you won't run the risk of cooking a pedal!
I don't have a signal generator here... my tools are mostly crude items like chainsaws and handplanes. I will try measuring the voltage across D9 -- only because it is physically near to the power input jack.
Disco Stu |
|
|
|
Disco Stu
Silver Member
USA
303 Posts |
Posted - 10/02/2008 : 21:59:33
|
OK --
Measured D9 with a KGB, lead in jack, LED on. It reads 8.85 Volts. I just thought to try that one as it is physically next to the DC input jack. There is also a little cluster of resistors there... have not attempted to measure yet.
The frustrating part of this pedal is that one can connect it between guitar and amp and hear that it works!  Just extremely muted, as if you turned down the guitar volume pot nearly all the way. The chip or chips that make the delay effect are definitely doing their job, and the pots that control "Delay Time", "Repeat", and "Delay Level" are all audibly functioning.
So I have to suspect some other component. Maybe the JRC 4558 is cooked? That's an Op-Amp, I gather, present in many devices. If that took the overvoltage hit, could that be the cause of the decrease in signal volume? Or is it more likely to be one of the resistors that measures out of the prescribed range?
Well, anyway, thanks for all of your tips and suggestions. It's not like I need this pedal to make a living -- I'm just an amateur musician. I can always get a few hundred feet of cable and make a real, genuine echo chamber! I've got plenty of mics and speakers.
Disco Stu |
|
|
|
Topic |
|
|
|
Fried Ibanez CD-10 - any tips?
