Actually it is a little better than I thought, it is the Promariner 1240i plus version, which does Battery Balance Control individually.

The ProTech-i Series battery charger incorporates industry leading technology, delivering fully automatic and
Sequential Multi-Stage Charging that provides electronically controlled charging, conditioning and
maintenance of all batteries and or banks connected.
High Line Features:
Automatic Wide Range / Global AC input 95 - 250VAC
Active Battery Balance Control (BBC) monitors charging while conditioning and extending
battery life ensuring that no battery is ever overcharged (1230i Plus, 1240i Plus & 2420i Plus only)
User Programmable Absorption / Conditioning Mode: 1, 2, 3, or 4 hours.
User Programmable Battery Type / Charge Profile Selector- 3 Settings:
Out of Box Factory / User Setting 1 : Flooded (Lead-acid)
User Setting 2 : AGM
User Setting 3 : GEL
Standard Features:
Advanced Electronic Technology yielding a heavy duty stylish and compact On-Board Marine Charger.
Expanded LED Operation Status Center Includes High Visibility LED's for:
Fast Charge, Absorption, Float, and Discrete Battery Type LED indicators for: Flooded, AGM and GEL Batteries.
Fully Automatic & Sequential Multi-Stage Charging (example below is for a 12 Volt ProTech -i model)
Factory set out of the box for Flooded (Lead-acid) battery (s).
Sequential Multi-Stage Battery Charging
Stage 1 Fast Charge = Maximum Amperage Output until Battery (s) reach 14.7 VDC
Stage 2Absorption Charge / Conditioning Mode = Precision 14.7 VDC to Fully Charge & Desulfate Battery(s).
Stage 3 Float / Maintenance/ Ready Mode= Precision Finishing & maintaince Voltage of 13.5VDC
Stage 4 Recycle / Dockside Power = If while docked and connected to shore power your Batteries have
a continuous excessive DC load for lighting, entertainment, or appliances, etc. The ProTech-i Series will
return to Mode 1 providing your batteries up to the full amperage rating of the charger to meet the demand
of the load and begin charging your battery (s).

 

Well, I was wrong about the main rectifier being bad, it's good.
I tested it out of circuit and it worked, till my meter probe slipped and shorted the negative to the AC lug. ugg... blew the circuit breaker.
I had ordered 5 from Aliexpress for $2.50, was planning to replace it anyway.

So it is just the bad open transformer. I know the power circuit is good as it is sending AC volts to the transformer inputs and rectifying DC volts using the smaller 10 amp inline bridge i had swapped in.

I will be sure to report back when I get these parts in a month.

 

I am tempted to hack saw the weld laminations apart on the transformer and unrap the windings and see if I can repair the ends of the coils.
An EI35 is a 2watt transformer, this one seems to have only 2 coils, in and out. Maybe if I get less busy.

I did something similar on a transmission solenoid once, and also a small ac evaporator fan for a fridge.

I did put in a 10 amp bridge rectifier, and nothing blew up.
The switching drive circuit is disconnected when the transformer windings are open, so nothing will happen as it cant switch the C4060 power transistors.
I cant find anything else wrong when going over the board than this transformer. I am pretty certain its the problem.

Its possible the charger just failed when charging too many batteires some time ago, burnt out the bridge rectifier. Then it sat off a few more years in the bilge of that boat and the salt air ate up the ends of the little transformer coils.

This particular model has some similar complaints, likely the same lousy transformer failed on the others. It's the weakest link.Little tiny copper wires exposed to hot salty humid bilge air, if you like your battery chargers, do not stick them in the engine compartment.

It may work to just lift the tape and gain access to the winding and you might even see the point of failure and be able to repair it. Just be very careful to avoid short circuiting any turns.

 

I had tried it, the copper traces are so tiny and the entire pin assembly cracked apart.
And when I managed to read a secondary winding, was 60,000 ohms or something which seemed really wrong to me..
No, its toast, foobared.
The corrosion ate the little tiny winding back into the core.

 

I had tried it, the copper traces are so tiny and the entire pin assembly cracked apart.
And when I managed to read a secondary winding, was 60,000 ohms or something which seemed really wrong to me..
No, its toast, foobared.
The corrosion ate the little tiny winding back into the core.

I realize that you are going to need to clean all of the salt out of the board and take additional measures to prevent salt entry in the future.

 

Transformer is here, it works. Amazing.
Exact fit to board.
2.8k primary, 10.9 ohms secondary. Secondary side center pole is not electrically connected.

It puts out 15.6 vdc with no battery connected, now I do recall reading with no battery it is supposed to pass thru the bulk stage onto the second absorption phase fast, but I see no change in volts, maybe it is just amps.
And occasionally relay buzzes louder than the video, especially if you pick up the board. but there was no change in output. Still waiting on the correct inline bridge rectifier.

Needs new transformer zip-tied to board, and I can check out the dip switches.
https://photos.app.goo.gl/KXBU6CRTYvuEMd2g7

 

It is out of calibration, 15.65 volts output is too high, should be 14.7.


There are 5 little blue pots on the PCB, and some have word voltage next to them.
I may try to see what happens if I turn them.
Maybe some are timers, some are voltages.
And I set to 1 hour the absorption phase then after an hour, volts are supposed to drop down to float 13.4

And sometimes the relay still goes loud buzzy. Rarely when it does that the output DC volts drop to 9vdc.

 

Ok, I think vr3 labeled 13v may be float volts
And vr1 labeled 14v maybe absorption voltage
They look like some shiny glue was put on them?

Looks like those VR pots are tied into 2 IC chips IC5 and IC7 which may be voltage regulators to the right.

What is OC for vr4 ? 'OC' mean anything to anyone?
Then there is Time Start for vr2

I am still waiting for it to switch to float mode.
I did set it for an hour.

I have not heard the relay do any more odd buzzing noises.

 

Tried moving those, but its not helping. If I move the Time start it does drop the output volts, but then it becomes unstable and jumps around.

Is it possible just too much volts are coming off the secondary of the transformer? It measures 7 vac.
Could the secondary volts be lowered, what is easiest way to do that?