I am planning to build some A/C Amplifier units for the Delanair II climate control system. I have a circuit design using 6 transistors as per the orignal, but driving the motor in the servo via a solid state motor controller chip instead of the relays. I have not built the prototype yet as I am away from home but have simulated the circuit using an electronics simulator app, and it appears to be working as it should in theory. If it does work in practise, I can produce these on a cost-effective basis, but I don't know where to source the connector plug that it uses to connect to the car wiring. Does anyone know if these plugs are still made / available anywhere?

I see on SNG Barratt's website they list C45402* as special order item at £352.07 + VAT which is an astronomical price. Their picture shows a unit complete with plug so that implies the plugs might be available somewhere.

 

i am aware of one amp maker that has the buyer of his amp cut and re-use the connector from the original amp. i installed his amp and am extremely satisfied so far. thank you for giving members of this forum more options.

 

David should have a bunch of those amplifier connectors laying around.
Contact him at www.everydayxj.com

 

Andy
Great plan. I can certainly send you a plug from my old amp and would be very interested in a unit.

 

OK I will make the prototype when I get hme next month and report back on its success or failure!

It might be a good option to install screw terminals on the printed circuit board for the user to connect the wires from the original plug, as per the photo in Retroren's post a week or two back. Meanwhile I have made enquiries for unwanted plugs with David.

 

David let me know that he has a long-standing arrangement with Jag-Aire to supply kaputt amps so they can re-use the connectors. I think the screw terminal connection will be the easy solution

 

Might get too complicated to do one wire at a time. Too easy to screw up the many wires and put them in the wrong terminal.
Do you not have a salvage yard nearby? Would be so easy to just cut the connectors.

Also consider that there are two different systems: the standard Mark II and the later Mark III. Do both systems use the same amplifier specs?

Complicated even for the experts.

 

There are plenty of salvage yards near me but none have Jags in them! Chock a block with Japanese scrap. Meanwhile Greg has offered to send me a plug so I'll be able to get started with that.
The Delanair III is a different system from what I have read.

 

It is, no amp of the DII type and no servo f the DII type either.

 

So I just built my prototype AC Amplifier and tried it in the car.



It appears to be working. I have added LEDs to indicate heat or cool (thought that was a good idea by the person who made Retroren's unit).

In the car, if I select cooler temp, the cooling side is activated; select warmer temp, heating side is activated, and also if on DEF setting.

However, I cannot be sure about it yet as unfortunately the servo motor on my car is reading open circuit, so the servo is not changing position. Tomorrow I will start trouble-shooting that issue. Anyway this looks promising so far, so I'll report back once I have checked into the servo problem.....if I can manage to get it out without dismantling the entire dash!

 

Andy
If you remove the RHS air louvre and then remove the trim piece you can get to the servo which is under a plastic dust cover that can "just about" be pulled off it. Then the actual servo has a single bolt attaching it to the unit which also can just about be got at. Then the servo can be disconnected from its rods and wires and wriggled out. Mark the positions on the rods of where they are clamped by the fixing blocs, and ensure they get refixed in precisely the same positions.

Usually with the servos it is the potentiometer that gives up and replacements are not available in the required movement range and resistance. If this is the case maybe you can find one that does work. If not I have a few old ones and can try to find one with a potentiometer that works properly.

 

I got the servo out earlier on....it wasn't as difficult as I had expceted, fortunately. Thanks for the tip - I have marked the rod positions.

The potentiometer is OK but the red and purple wires to the motor read open circuit. Checking it over on the bench I have found that one of the two diodes has gone open. I just went to my local electronics store but they don't stock that diode. It is a 5W Zener diode of 3.9V coded 1N5335. I have ordered a pack of them from eBay instead.

The spindle for the two levers that actuate the rods had also come unscrewed, so they were flopping about. Otherwise it looks like it should be OK. Metering out the motor from beyond the diode, I get 30 Ohms which is as it should be.

I'll have to put this on hold for a while until I get the diode. Funny how these jobs get longer and longer! If I get the servo sorted out, I suspect I will have a bit of a battle to follow with the vacuum tubes and actuators. One step at a time though....!

 

Hi Andy,
Did you unwrap the electrical tape from the massive wiring bundle inside the servo ? There is a small pcb inside with two more diodes ! When troubleshooting my malfunctioning servo I replaced one of the other diodes next to the motor before finally finding the problem was a cold solder joint on that hidden board, mimicking a blown diode. I'll see if I can find pictures to post for anyone who needs help later.
Cheers !
Brian

 

That’s useful information. I have not unwrapped the tape yet. I was wondering why the diodes next to the motor do not match the circuit diagram in S57.

The diode I have removed is definitely open circuit and needs replacing but now I know to dig deeper if that doesn’t make it work.

 

Correction 3 hidden diodes on the board ! Picture of the servo with board still taped and ziptied, then one opened up.




Cheers,
Brian

 

I had the same problem when trying to match the S57 to what I was actually seeing. Finally started tracing the circuit path to make my own diagram when I found extra wires entering the tape bundle, opened it and bingo the missing diodes ! When bench testing I was able to wiggle the wiring and get correct readings / function, so after re-soldering the bad joint it works perfectly !

 

This project is really valuable, I want to thank you blokes for getting stuck in. The Delanair II system is actually very reliable, providing the amp and the servo are working. So, assuming success, this will help many owners keep their cars aircon going as per factory.

 

Good News! My servo is working now.
This morning I re-tested the zener diode I took out yesterday, and it was OK after all. I must have had the meter set incorrectly or something yesterday. I did as Brian recommended - untaped the hidden diodes and re-soldered them to their little board, and then the motor started working again.
It is fitted back into the car and the new Amplifier is working correctly, driving the servo in the required directions.
Now I have started troubleshooting the vacuum system. The tubes have been messed about and incorrectly connected, and I have leaks in the actuators for the blower unit flaps and centre dash vent flap.Will see if I can source replacements for those next. The demist actuators are working correctly.

 

Sorry to resurrect an old thread. Did you ever produce these amplifiers? I’m in the UK so the US suppliers are too expensive for me.

Also the manual says to check the diodes before condemning the amplifier. Does anyone know how to do that?

thanks.

 

Yes I have made a batch of repro AC amps using a solid state chip instead of the original pair of relays to drive the servo.

I went through several iterations of the design and ended up with one with a set of 3 LEDs that fit into the LH ashtray to indicate system functionality. That is optional - you can omit them of you don’t require that or prefer total originality of the look of the interior. The amp itself is smaller than the original and easily slips inside the trim panel where the lower vent is located.

PM me if you are interested in purchasing one. Cost is £100 post free worldwide (dispatched from Thailand)