I will think about these measurements. Please go back to my post 75 and measure that resistor voltage. It will tell us how much current is flowing in IC802.
I keep thinking that you may have been fooled into debugging the wrong board. Unplugging any board may shed enough current to cause the +/-16 supplies to recover even though the problem component has not been removed from the circuit.
let’s get that resistor voltage before we think about attacking another board.
I keep thinking that you may have been fooled into debugging the wrong board. Unplugging any board may shed enough current to cause the +/-16 supplies to recover even though the problem component has not been removed from the circuit.
let’s get that resistor voltage before we think about attacking another board.
@Potentiallyincorrect, did the .4mv voltage drop across R828 or the other voltages measured On IC802 raise any flags?
Did those voltages I measured off of the pins on IC802 have any bearing especially that 9.6v on pin 22? So here’s what I did, I bought another FEQ board and I’m going to pop it in this weekend. I’m curious what that will bring.
Hi Ciscoguy2,
Sooo ... why did you follow the thread here? Are you having a problem, if so what is it?
I was the Canadian Factory warranty for Carver.
Sooo ... why did you follow the thread here? Are you having a problem, if so what is it?
I was the Canadian Factory warranty for Carver.
No, unfortunately it did not. Something is dragging the +\-16vdc rails down. What I did was unsoldered the phono from the switching chip and the voltage came up too +\-14.8vdc. Something is still dragging the rails down but it was enough for me to be able to bias the amp section. Perhaps someday I’ll dig back in to it. I’m thinking it’sa bad cap somewhere.
Hi luvrockin,
It could be an op amp. Both supplies are being dragged down? If it was a capacitor I would expect one supply to be affected. These are simple resistor - zener diode type supplies. You could check the 680R resistors in case they both increased in value. But if both supplies are down, suspect an active component between those two rails.
-Chris
It could be an op amp. Both supplies are being dragged down? If it was a capacitor I would expect one supply to be affected. These are simple resistor - zener diode type supplies. You could check the 680R resistors in case they both increased in value. But if both supplies are down, suspect an active component between those two rails.
-Chris
Well, I recently purchased a MXR 130 that worked perfectly, nice shape, and it sounds incredible. So I thought I would purchase another to play with it. After reading all this, and other sites, I realize the Carvers are NOT the easy fix as the Sansui's I have been working on.
I replaced the relays, and it still is in protection mode I guess. Doing the first amp alignment procedure I did manage to get the voltage set right, but didn't have the dummy loads in place, so I am not sure if that makes a difference. I also broke the only small plastic screwdriver I had. So I got a new plastic screwdriver, still waiting on the dummy loads.
I did check the idling without the loads, and it's close, but also seems to wander. Waiting on better clips for my Fluke so I don't have any slips and fry me or the unit. I did notice on my working one, that the display does not show, on FM until the relays click in. So I think the second might be okay there because it does show it tuning.
I think I would be better off starting a new thread, and seek your assistance. Not in a hurry, just wanting to learn. I can check voltages okay, I just wish I didn't have to read multiple threads to get all that info, but then again, maybe little by little is the way to go. I have good soldering equipment, just some days my hand resembles that scene in Blazing Saddles.
So what do you think? Start a new thread?
Thank you Chris for your suggestions. I’m going to try and peck around with it a little bit this weekend ifi gets chance now that this thread has been reactivated and its reminded me. Once I was able to get the bias, I let it go. It does make sense what you’re saying that it’s more than likely common to both rails. If it was bad cap, it makes sense the issue would be isolated to the + or - rail vs + and - rails. I replaced those (4) hot resistors when I first picked up the 130 and increased their wattage to 5W as well.