1983 ypvs controller repair

[nextfridaynite]

My 1983 rz350 came with non functioning power valves. The servo would not cycle when the ignition was turned on nor while the engine was running. I checked the servo motor for operation per manual spec and it wouldn't move with the required 12v applied. Also I hooked up a volt meter to the controller output and turned the ignition on but no voltage was coming out of it.



After reading some posts here, I learned the output transistors are the most probable cause of failure and as my servo motor wasn't functioning either, I hoped this was the problem. There are four transistors on the pc board that are easily replaceable and I was surprised to find them on ebay for under $10 shipped. The part numbers are B834 and D880. 2 of each are required.





After peeling away the sealer off the motherboard under the transistors I Desoldered the pins and removed the transistors from the pc board, used the old screws/nuts holding the units together and inserted the new assemblies onto the pc board and soldered them in, then trimmed off the excess pins.





I hooked it up on the bike with a known to be working pv servo and turned the ignition on and heard the robotic whirr of the pv servo as the power valves cycled. For under 10 bucks you too can fix your ailing 1983 controller yourself.







sent from my etch a' sketch using see n' say

[silverstrom]

Well done! Great post. Thanks.

[JonW]

great post!

[hondaror]

That's awesome!

[smokin074]

Thank You for posting with the photos. Terrific.

[norwayYPVS]

Great Post! Have ordered the transistors.

Thanks!!
Hans

[JonW]

I used this post today to repair my 83/84 (US85) units that were both dead when plugged in and ignition switched on.

FWIW The later versions do not have these B834/D880 Transistor sets so I assume are not repairable, certainly not as easily. These are large parts with big solid steel feet and even a pretty incompetent circuit board repairer (like me, im good with wires but little components on a board scare me) can do these I reckon. I did buy a digitally heat adjustable soldering iron from ebay - a chinese cheapie - and some 0.5mm solder and already had a solder-sucker. Those things are all you need really other than the transistors which you can buy cheaply on ebay.

ok, I worked on the two dead units I had here:

1, On one, changing these out solved the issue and when keyed on the servo spins over and back like a new one. Fast and seems dependable. Perfect!

2, I wasnt so lucky with the second controller tho. I swapped these transistors out and it was still dead, but wobbling some wires got it spinning the servo. The problem is that it spins the servo what looks like a full revolution at medium speed, and then pauses for about the same number of seconds and then spins it the same way again the same amount. Defo not useful on a bike, that would rip the cables to pieces.

Ive no idea what is wrong with the 2nd unit (any ideas?). I did wonder if it is the PU4310 mentioned in this thread: viewtopic.php?f=3&t=6462&p=54414&hilit= ... tor#p54414

I do sort of doubt that tho as that PU4310 unit is like another set of power supplier transistors from what I can glean from that theead. The fault I have seems more like I have the power, but its not being controlled right. Like its logic is gone or what it receives back from the servo isnt getting through. hmm..

Anyway, I am very thankful to this thread that I have at least been able to save one of these units.

Anyone who has one they dont want to repair, and would only stick in the trash, feel free to send it to me (I'll cover the costs of course) and I'll try and fix it to replace my dead one, but really if youve the time and the kit I suggest you have a go at doing this.

Oh... And before you ask, no I dont want to get into repairing these for people. its a bit of a faff peeling back the gloop on the board, unsoldering and re soldering the transistors (which took ages to source from china) and then when its all done finding out there is some other issue and its all been for nought etc. If we could be certain these were the fault everytime it would be different i guess, I'd buy a bunch of the transistors in and open up shop lol.

[Whymee]

Outstanding post and subject matter!