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November 30, 2021, 01:03:54 AM

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91
Amplifier Discussion / Re: Fender M80 Issues
« Last post by Enzo on September 25, 2021, 09:17:15 AM »
Transformer is likely just fine, it makes AC.  I was concerned with the DC supplies.

15v 16v whatever.  It is the low voltage supply for the op amps.  SOme amps use 12v, I see 17v a lot on some mixers.   Your problem is that the preamp is just not working at all, and the lights don't even work.  This is not going to be because voltage is off by one or two.  I'd be concerned one or both supplies are MISSING.

Iy is just a place to start.  NO circuit works without good power supply.
92
Amplifier Discussion / Re: Fender M80 Issues
« Last post by Angelopz on September 25, 2021, 08:22:22 AM »
Ok I will check the transformer in the back. There are 3 wires on the low voltage. One is the center tap. Voltages according to schematic are 40v and 16v. I hope this is what you are talking about. I know you said 15v but I don’t see that on the print.
93
The Newcomer's Forum / Re: Orange Crush 12L (No Sound)
« Last post by Mark N on September 24, 2021, 10:49:11 PM »
Thanks again, Enzo!

Flester, sorry to hear yours fell apart, but glad to see you reused what you could. This lil' amp does sound good. Once I get it fixed up I'm debating whether or not to keep it. I've got too many amps as is and I'd rather not have it keep breaking on me. It definitely is fun to play though.
94
Amplifier Discussion / Re: Fender M80 Issues
« Last post by Enzo on September 24, 2021, 08:41:41 PM »
Start with the low voltage supplies, +15v and -15v.
95
Amplifier Discussion / Fender M80 Issues
« Last post by Angelopz on September 24, 2021, 03:50:11 PM »
I have my original M80 combo amp with the speaker. I haven’t used it for some time and was fully operational when I stored it. I just got it out and hooked it up and found that the 2 inputs don’t work. Also there is no light on the overdrive and when I plug in the pedal no light on that. The power light goes on and if I plug into the power amp in with my guitar, I hear my guitar. Looks like I’m not getting power to the inputs or something. Anybody out with some ideas? Would really appreciate it
96
Amplifier Discussion / Re: I would like to build an audio signal detector
« Last post by yeto on September 24, 2021, 07:11:22 AM »
:) sounds good

I appreciate your help
97
Amplifier Discussion / Re: I would like to build an audio signal detector
« Last post by Enzo on September 23, 2021, 03:07:35 PM »
What if it DOES work?   If it doesn't, we can determine what is wrong and fix it.
98
Amplifier Discussion / Re: I would like to build an audio signal detector
« Last post by yeto on September 23, 2021, 01:31:50 PM »
Thank you for taking time to reply.

Would you have any recommendations as to an amateurs way to "sort of" check the circuit if I get everything put together but the amp doesn't work. I  haven't started yet except for gathering parts but I just want to be prepared in case I run into trouble.

Thank you,
yeto
99
The Newcomer's Forum / Re: Orange Crush 12L (No Sound)
« Last post by Enzo on September 23, 2021, 11:17:16 AM »
You have 13v on the output pin of your op amp instead of zero.  Doesn't matter that the amp is different, that still sounds like a bad op amp, so change it out and see if progress has occurred.  For small practice amps like this I rarely get out a schematic.
100
Amplifier Discussion / Re: I would like to build an audio signal detector
« Last post by Enzo on September 23, 2021, 11:14:05 AM »
This calls itself a signal detector, not a signal generator.   I have a guitar next to me in the shop, but mostly I just use a signal from my little shop stereo receiver tuned to a music station, or sometimes a CD player.   All I need is a signal for testing, it doesn't matter a lot what it is.   Of course you could use an actual signal generator (oscillator) if you have one.  It keeps your hands free.


And honestly, any amp running on 9v will likely be very simple and basic, meaning there won't be many stages in the half built steps where listening tests will lwork.
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