Aerodon

Almost correct, the ground from the avionics switch goes to the main grounding bus, not the alternator ACU.

OK, so you probably need to look at two things: 1) if you have the big round solenoid type relay, your plane has probably already been upgraded. From the wiring diagram the original relay was a multi pole relay with the terminals 'paralleled' for higher current. So if you have that, go ahead and get it changed. 2) There is something wrong with your control relay. These are inexpensive and plug in and out. It could be the relay, or broken wiring, or bad contacts with the base of the relay. If the avionics are not turned off by either the switch or the 'engine start', then it is a problem with the ground wire to the relay. The ground wire is short, it goes from the relay to the grounding block nearby. Attached are pictures of the control relay, part number W67CSX-3. Aerodon

Shawn, The way the avionics relay is wired up, if you inadvertently try to start while the avionics are on, the starter switch should also turn the avionics off. I looked at my CB panel assembly again, it would appear that I do not have the original avionics relay, I can see where this relay was removed and replaced by the 100A solenoid (as shown here), probably as per the service bulletin kit you have received. Aerodon

The more I look at this relay, the less I like it. It weighs 1lb, has 5 Ohm resistance, so draws 5A to keep the avionics off just when you really don't want to be drawing current from the battery before and during startup. I have seen several aircraft with just a high quality CB switch (Cessna) and sometimes a 'hooded' second CB switch (Piper) for backup. Aerodon

The M20K has a small avionics toggle switch, the kind you have to pull to toggle so you don't inadvertently bump it off. And like I said previously, it is a monster avionics relay, so I can see why they did a control relay. But then there are multiple points of failure. (And no simple 50A breaker switch for emergency power like Piper did). I looked at the M20R wiring, and as far as I can see it has a 3A rocker avionics switch, instead of the control relay. I'm in the process of installing one of these rocker switches as part of the panel upgrade, so I may as well remove the control relay to make it more reliable. One less CB in the RHS panel too. Aerodon

Agreed, but the large relay is a 'starter size' relay rated at 100A / 28V. The control relay is a flimsy 'plug in' style. And there is a diode in the wiring, IIRC there are some serious consequences if this diode wire breaks, I need to go look. I do not like the way the control relay wiring crosses all the other wires, could easily lead to inadvertent damage. When I look at the Mooney wiring overall, I think they were trying to be too clever for their own good - more complexity than needed, more intermediate connectors (with nice gold pins). Aerodon

There are two avionics relays. The smaller copper coloured one is the 'avionics control relay' and the larger one is the avionics relay. For reference the circuit breakers are on the LHS of these pictures. The square black box is the prop deice timer. The square silver boxes are RF filters. You can see the ammeter shunts mounter on the 'inside' side wall. The avionics relay is also mounted on this inside' side wall. Would appreciate pictures of the new relay please. Don

I have a replacement relay for you, from a 1996 Bravo. You better hope it's not the relay, it sure is buried in the panel, behind the circuit breakers. Looks like the first thing they install. I can take pictures. Don

It is possible, the 760 is about 7.3 tall by 4.9 wide in portrait mode. If you have 'standard' second stack, the Gizmo mount should work, it's designed for a 6.26" stack. I'm developing a flush mount similar to the Garmin G5 flush mounts - a backplate for the cradle that is set back enough so that the 760 is flush or protrudes 1/8" (not sure what will look better yet). This is part of my 3/4 panel, but there is no reason I could not make a 'second stack' replacement panel to achieve the same without redoing the whole panel. And this is the second 760 in the plane for the copilot and to fill the blank space, the other one is on the yolk. Aerodon

I'm curious to see how you fit all that into the panel. Here's my latest iteration, I've managed to get all the radios into the centre stack, but there is not enough space for an Air Gizmo mount in the second stack. I'm playing around with a backplate and cradle to flush mount a 760. And this is a second 760 for my co-pilot, I prefer the yolk mount 760. Aerodon

Bruce, any idea if it is the same as a 1986 M20K, I replaced all my instruments with a JPI and have the old instruments laying around somewhere. Don

I'll take it - my hose is too short, happy to pay you something. Don

Once you start installing a new audio panel and / or a GTN you are redoing more than half the avionics wiring. It is worth updating the audio panel wiring all the way to the jacks (stereo, shielded, separate audio and mike, and not grounded on the one end). And it is entirely practical to beg/borrow/steal a full set of trays so that you avionics shop can completely wire up your new panel before you even start disassembling. Mooney was too smart for their own good. They made up nice cable harnesses with CPC and AMP connectors all over the place. I'm sure it helped a little bit in manufacturing and assembly, but there are just too many. The M20J's and K's onwards had a separate circuit breaker panel and it has a shelf with electrical components mounted on it. I thought of discarding this and going with a 1 piece, but it will help reassembly to have the circuit breaker panel in place before installing the rest of the panel. It was pretty easy to take out the panel and the circuit breaker panel and separate the avionics wiring from the electrical system wiring. The electrical system has a CPC connector, these are high quality 15A pins. The avionics are all on a rectangular AMP connector, also high quality 15A pins. The standard Mooney ground bus is a bit old fashioned - terminal strips with screws. I like these AMP grounding blocks, see image. But you do need the proper crimper and it is pretty expensive. But the more you make your panel plug and play, the less time the avionics technician needs to spend sitting in the airplane terminating one wire at a time. On an older Mooney I would do a single piece panel but with an insert for all the circuit breakers. I have a design that allows the insert to be installed from the back, but also removed from the front. So you can install circuit breaker panel first, then put the full with panel on top. And if you ever need to change or update circuit breakers, you can take the sub panel out from the front. Aerodon Edit: Added a picture of the TE Connectivity CPC (circular plastic connector). Gold plated stamped pins are about $1.50 each, machined pins are about $2-6 each depending how good you are at bottom feeding. Proper crimpers are $4-700 for these.

Here's a mockup of what the stack would look like. Might be too tall for a single stack in a Mooney. Height can be reduced buy using an SL30 navcom isn SL70 transponder. GNS530 Stack.pdf

Do you have any before and during pictures, I like the horizontal G5 layout. I'd prefer to switch the clock and EGT positions, keep all engine stuff together. Aerodon

I have a complete G500 system for sale and will throw in a free custom M20J/K panel for you (CAD and machining service). GDU620 display, GMU44 magnetometer, GRS77 AHRS, GDC74 Air Data. GAD43e also available to interface to autopilot and analogue devices. Aerodon

These are installed in line with your transponder antenna to get ADSB out on 978MHz. Built in GPS receiver, GA35 GPS antenna. They work well if you have a decent transponder, I have heard that there are problems if you have an older transponder. (Colllins, ARC etc.) These list for $2200, best street price I have seen is $1995. Aerodon

I'm looking at my plastic glarehield and have a few questions. Has anyone made one out of aluminum, is this allowed? And is the glareshield panel lighting required with a mostly glass panel. Occasional post light or Nulite on unlit instruments? Aerodon

Hank, I tried subbing the CAD work for my CNC machine and could never get the accuracy required. So I buckled down, bough a decent CAD package (draft sight) and taught myself how to draw again. (I used to be really good with a pencil). I have an extensive library of panels and instruments, know which instrument holes to make slightly bigger, slightly smaller etc. And I know how to generate the curved outlines of the panel too. And I'm pretty good and laying out the instruments so that the panel looks right, does not obstruct behind, etc. At the end of this, I am not prepared to share the CAD file, but quite happy to provide a design and CNC machining service for new panels. Aerodon

This will be expensive but a good deal for the right person: PM8000 or PMA450 audio panel, GTN750, SL30, SL70 with Approach Pro-X Hub and cables. This is a nice 'low height' stack that will fit into a single stack in most Mooneys with enough space left over for a GFC500. I do not need to sell all of the components, send me a PM and tell me what Mooney and avionics you have already. And I'll do a boxing day special on a new CNC panel too. Aerodon

I have a GNS530 with the start of a Pro-G hub and cables, including a new 530 and audio panel cable. I also have an audio panel, navcom, transponder, G5 to go with it. Contact me directly for some pricing, I'm ready for a boxing day sale so that I can replenish my airplane upgrade budget. Aerodon

Not sure @Modify201 has a 430W, maybe just a 430? I may be incorrect, but my understanding is that a GFC500 will work best with a GTN because everything is integrated. And, trust me, I've been done the rabbit hole and back with 'while you are in there may as well'... There are a huge number of wires going to audio panels and GPS/NAV/Coms like GNS430/530's. An upgrade to a GTN requires at least half the wires to be redone, sometimes it is easier just starting from scratch again. But I get it, hardware prices add up pretty quickly. Aerodon

Post a picture of your panel please, from what I can see the C has several different panel structure layouts? You don't mention indicators for your radios? Prices get out of hand pretty quickly. I know you already have the 430 and GTX345 - both are saleable, especially the 345. Mooney's are short on panel space, if at all possible go for a remote transponder mounted on a rear avionics tray? But you need a GTN to control it. I'm a fan of a single stack in Mooneys, there is a way of doing it. The GMA audio panel looks good, but if you are on a budget there are good used PS7000's and 8000's available. Put the money towards a GTN? Aerodon

Mark, Send me a PM, I'll swap a standard audio panel for yours with the DRAWS option? Aerodon

Disagree, I have a PS7000 with the DRAWS option and it definitely talks. Aerodon