Hi,
Check the three boards drawing that shows the parts. The one in the bottom name MA 6S BUS CONNECTOR drawing. You can see the resistor R54 at the right end. If you can see the resistor that is where you need to solder the resistor. Let me know if you can see the resistor. I do not know if you can be able to see it since I never worked with this amplifier.
Check the three boards drawing that shows the parts. The one in the bottom name MA 6S BUS CONNECTOR drawing. You can see the resistor R54 at the right end. If you can see the resistor that is where you need to solder the resistor. Let me know if you can see the resistor. I do not know if you can be able to see it since I never worked with this amplifier.
Yep .. I can see it. Side panel is removable too so this should be no sweat. Buss connector is elevated about 1/4" above the heatsink ... everything is screwed to that. Amp cards are perpendicular to the buss connector and on edge of course. J4 is the PWR module end.
Probably need to remove everything anyway to get underneath the buss connector.
Probably need to remove everything anyway to get underneath the buss connector.
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I expect you're right but I'd come at it differently. I'd see if I could power down the +/- 45 supplies a few seconds before killing the +/- 15 supplies. If the power is gone any thumps from the 15 system will have no power to do harm.
G²
I will look at it closer today tauro0221. Replacing components isn't a problem ... I can solder pretty well.
I'm not sure how to go about adding this resistor.
For instance ... if I can see the trace for the +60V, do I attempt to solder a short lead wire from that and the HI Level GRD so I can mount the resistor next to the one already there (on top)
... or can I solder both resistor GRD legs together on top and run a short lead wire to the AMP card connector's +60V leg.
Same issues/questions in my head about moving the two diodes. I can find point A and B but what is the proper way of connecting both?
Does adding a short length of wire screw up the resistors value? <-- this is the kind of knowledge I lack ... but I know enough about repairs to know a what a cobbled together job looks like.
I'll do more research on how to do the things you suggested properly and go from there. I know my limitations.
Thank you again!
Phil
I'm not sure how to go about adding this resistor.
For instance ... if I can see the trace for the +60V, do I attempt to solder a short lead wire from that and the HI Level GRD so I can mount the resistor next to the one already there (on top)
... or can I solder both resistor GRD legs together on top and run a short lead wire to the AMP card connector's +60V leg.
Same issues/questions in my head about moving the two diodes. I can find point A and B but what is the proper way of connecting both?
Does adding a short length of wire screw up the resistors value? <-- this is the kind of knowledge I lack ... but I know enough about repairs to know a what a cobbled together job looks like.
I'll do more research on how to do the things you suggested properly and go from there. I know my limitations.
Thank you again!
Phil
Could I just add the resistor right on top of the last amp cards buss connector? Find the GRD leg and the +60V solder resistor between ... this added resistor will be on the amp card then ... no need for short wire leads.
On the diode(s) (D18, D19) simple as leaving one leg where it is (the one connected to either + or - 60V) and using a short jumper from other leg back to "L3" connection?
On the diode(s) (D18, D19) simple as leaving one leg where it is (the one connected to either + or - 60V) and using a short jumper from other leg back to "L3" connection?
Hi,
I think you have the idea. What about solder the resistor to the exiting resistor ground side and solder the other side to the +60. In the diode I will raise both side of the diode connected together from the board and solder a wire from both diode together to the relay side that the coil is connected.
I think you have the idea. What about solder the resistor to the exiting resistor ground side and solder the other side to the +60. In the diode I will raise both side of the diode connected together from the board and solder a wire from both diode together to the relay side that the coil is connected.
They just extended the GRD and -60V out to the resistor pad (on PCB) ... the other voltages stop at the last connector on the buss card. Would not be enough room underneath the buss card for a resistor of this size. Mounting it on the connection pins of the amp card would be simplest and not require any disconnection/de-soldering down the road if need be ... and no jumpers.
I understand about the diode(s).
Now to see if the RS/"phone store" in this one horse town of mine still has a resistor in stock
What gauge wire would be appropriate for the diode jumper ... does this matter?
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Keep it simple and try and determine the real cause
How long after turning off until you hear this thump ?
Approximately... less than 1 second,
more than a second,
5 seconds ?
or the instant the switch is opened ?
How long after turning off until you hear this thump ?
Approximately... less than 1 second,
more than a second,
5 seconds ?
or the instant the switch is opened ?
Mooly ... in case it wasn't clear in the first couple posts the "thump" happens the instant the switch is pushed OFF. Does this if it's just unplugged too. Doesn't matter where the sensitivity controls are set (full up/down) .. doesn't matter if there is any input signal or not ... first on last off not an issue either as it does this "stand alone".
The relays switch ... just not keeping up with the switch it seems. I know they are opening when the PWR is cut.
Funny you ask .... buttoned it up for now and hooked everything pack up ... turned on an FM station and yuck! ... sounded like ***. I have some CD's playing right now and it sounds fine ... FM ain't what it used to betauro0221 said:
As for volume (shrug) seems OK? I guess I could do a real A-B later.
Mike's "simple idea" is starting to look pretty good right now though.
If it wasn't for that fella on Rane's forum saying he did not have this trouble I'd tend to think that it was kind of common ... and that most people just lived with it. I'm having enough trouble trying to wrap my head around what's going on right now. Wish I knew somebody with an amp like this owned from day one.
Since that is the case, the most probable cause is the power switch sparking. I would replace capacitor C51 (0.01uF/600V) with a new one.
... funny you mention that. I asked the guy @Rane about that very thing " ... we never had one of those go bad. ... must be something else, like the switch." If I unplug the unit it still does it ... can't be the switch.
C51 is easy enough to get to without stripping the unit down I think. I'll give that a try next.
tauro0221 ... did an A-B on the volume. It is down on power with the resistor in place. Seems like 20% or so to my ears. (switched OFF and left controls where they were ... took out resistor and had to cut everything back all the gains. Don't have a SPL meter but this one was pretty obvious) Hey, it was worth a shot buddy!
Thanks guys
Phil
He could be right, these caps are very hardy.
It certainly can. By simply pulling out the plug, a spark can still be created, not at the power switch but at the plug itself.
You can try plugging it in to one of those "power strips" and use the ON/OFF switch there. If the amp does not thump when you Power Off, then it confirms it's either the amp's power switch or the cap.
Interesting. Looks like it's either the main supply caps discharging at different rates or the opamp rails.
If you decide to use my "simple" solution, it would be better to house the relays in another box with it's own power switch. This way, you can switch off the relays first followed by switching off the amp.
If you decide to use my "simple" solution, it would be better to house the relays in another box with it's own power switch. This way, you can switch off the relays first followed by switching off the amp.
Is it possible to just cut the +24V circuit with another switch (like a push button "standby") right off the PWR module ... keeping it inside the same chassis? ... or would that be a bad move?
(looking at the thermal switch on the schematic in that +24V circuit ... something like that except manually operated @ the front panel. .. momentary push button .. hold it while switching OFF)
The relays work .. just trying to figure a way to open them before I PWR OFF.
(looking at the thermal switch on the schematic in that +24V circuit ... something like that except manually operated @ the front panel. .. momentary push button .. hold it while switching OFF)
The relays work .. just trying to figure a way to open them before I PWR OFF.
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