Alternator out warning board

[Pete Somers]

Hi all
Could anybody send me the p/n for the alternator warning board on the top front firewall F337G '75. This one has got badly corroded and in need of replacement.

Thanks

Pete

[Guy Paris]

Pete,
Can you post a picture of the part that you need the number for?
guy, the old 72 driver...

[Pete Somers]

Hi Guy
I have not got a picture of the board, but it is the one on the top middle of the front engine firewall, with the big diodes and 2 fuses mounted on it. And a terminal block at the bottom. It controls the alternator out lights. I have a circuit diagram but no parts list, and this one is BER.
Many thanks for your help.

Pete

[Mark Hislop]

There is an alternative to getting a new circuit board. You can replace the board with an STC'd replacement from Elecronics International that will give you a digital volt meter/ammeter. I am getting ready to do this during my annual starting in a couple of weeks.

Mark

[Pete Somers]

Thanks Mark

Could you send me the address and email if poss so i can get and idea of the cost.
Problem is the Skymaster is UK reg so it is geting passed the CAA, however if there is a STC that would make it easier.

Many thanks for your help
Regards

Pete

[Mark Hislop]

Peter:

You want to use the VA-1Axx unit from Electronics International. The xx indicates the size of the shunts needed, which depends on which alternators you have. You can see the unit at http://www.buy-ei.com/VA-1A.htm . List price is $342 (USD). You also need a switch RSVA-3 so that you can monitor each engine on the single instrument. List price for the switch is $98 (USD). You also need two shunts. The S-50 shunts are rated for 50 Amps, and their price is $35 (USD) each.

Hope this helps.

Mark

[kevin]

Guys,

In aviation, as in most things, there are always multiple opinions. Mine is different from Mark's, and I offer it here for you to consider.

I had the EI volt/ammeter in my P337, along with the switch and the shunts, and like Mark, I think it is an excellent unit. In fact, I would not own a 337 without putting one in, because the electrical system is the weakest system in Skymasters.

That said, I did not, and would not, replace the overvoltage board you are talking about with this meter. I would have the meter *in addition to* the board. I am very uncertain that installing the EI VA meter actually can be used to replace the board, but I will take Mark's word for that. I thought the meter was STC'd to replace the Cessna ammeter. But anyway, here is why I would not replace the board with the EI meter:

If you wire around the board we are talking about, you lose, at least, your red overvoltage, red discharge and yellow "alternator out" lights. The EI meter provides a discharge light and an overvoltage light only. The problem here is that if you lose a single alternator, and you have only the EI gauge, you will have no immediate indication that anything is wrong. In fact, the only way you can detect the loss is to switch the EI guage from the left to the right alternator, and look at the current being produced by each. If the EI gauge shows zero for one alternator, then you would know that the alternator selected has stopped producing current (which may or may not mean you have an alternator problem, but that is a whole 'nother story).

If I am flying IFR on a dark and stormy night, I want to know *immediately* when one of my alternators fails. I have had exactly this experience on my '65 337 when the alternator shaft coupling failed. And I would find it a pain in the butt to have to train myself to check the alternators every X minutes by flipping the switch.

So my recommendation, for what it is worth, is to install the EI VA meter, because it is so helpful in diagnosing electrical system problems. But also, I suggest you repair or replace your warning light circuit board, because it provides an important function as well.

My two cents, worth what you paid for it.

What problem are you having with the board that leads you to want to replace it? Have you thought about having your avionics shop take a look at the board, see if can be repaired?

Kevin

[Mark Hislop]

Kevin:

You've given me something to think about. I was told by somebody at CPA that the STC would allow me to remove the circuit board we are discussing. Now, I am wondering if that is true, or if the STC only allows replacing the Cessna ammeter (which I don't have in the first place). And I am intrigued by your thoughts on having both, although the diodes and capacitors on the circuit board are a source of continuous maintenance. I'll have to think about this.

When you put in the EI VA, where did you locate it if you left in the original circuit board?

Thanks

Mark

[kevin]

The meter went in the instrument panel, as did the switch (well, you asked ;-). The actual indicator went on the co-pilot instrument panel in the hole where the Cessna EGT used to be, to the right of the fuel flow indicator and just above the copilot control wheel. The switch went below the cowl flap switches. I will attach a picture in the next message (not this one), you can see the switch on the lower left, and a small slice of the voltammeter on the far right. I will attach another picture in the next message after that showing the volt ammeter better.

The shunts went on the left (pilot's) side of the firewall in the engine compartment. I can't remember, but they were fairly high up, fairly accessible from above.

The board is undoubtedly a pain. I think I had to mess with it to fix it at least three times in five years. One of those times I think we replaced it, and at that time, while not cheap, it was not crushingly expensive either as I recall. But maybe time heals financial wounds...

Kevin

[kevin]

Center instrument panel.

[kevin]

right panel.

[kevin]

One more point, you can see in the second picture that the plastic around the gauge has been reshaped with a heat gun. This was done to make the discharge warning light on the guage visible from the pilot's seat. Without the reshape, the plastic covered the pilot's sight line to the warning light.

Kevin

[Mark Hislop]

Thanks Kevin. That is very helpful.

Mark

[Pete Somers]

Thanks Kevin and Mark

Kevin the printed cicuit board has suffered from the best of English weather and is very corroded, i have repaired it many times and it is now beyond repair.
So i am looking for a part number for a new PC board (if they are still avialable).

We were just discussing the point you made about the ALT out lights, and you are quite right i would not be happy without these lights, if an alternator went out you need to know.

So it is back to the PC board, if anyone could help with a p/n for the complete assy i would be grateful.

Thanks for the pictures Kevin.

Regards
Pete

[kevin]

Sorry Pete, I gave my parts and service manuals to the new owner of my airplane when I sold it (sound of grown man crying). I hope someone else on the site can look up the part number for you for your '75 F337G.

Kevin