Hi guys, I am trying to repair a RS-909CH, which is a cousin of RS-DC8 and would like to ask you for some help and expertise. Here is a short video describing the issue and what was done to diagnose it: youtu.be/1jfttDvYeaU . Thank you!
Have you changed all 3 gears? It is always needed to change at least the one on the motor.
You might have a motor failure or electronics failure coming from the RW board / electronics on the back of the mechanism. When you power on, the motor should engage and close the door.
I hear non of that in your video. One thing is to put a small amount of voltage on the motor after removing it and measure if voltage arrives to the motor from the control board.
These engines tend to fail more frequently.
Maybe check if all the cables are well connected.
Always good idea to do that first. I inspected and reseated all connectors as the first step, but no joy.
Thank you for the useful info, because I don’t know what is the expected behavior.
The occasional click comes from that electromagnetic actuator. You are correct, no buzz coming from the motor, which should happen even if a gear is broken.
I took the transport out again and checked the both motors. They are working when I apply 5V, moving the mechanism. However, it looks like rewind/open/close motor gear is damaged, but still works. I rechecked the surface mounted electrolytic capacitors and most of them don’t look good. Obviously, I still don’t know if it is only these caps or any other board component.
Regards,
Vlads
Start by recapping the RW board under the metal plate behind the mechanism before doing anything else.
That is actually my plan, because under a closer examination i see that solder joints around a few of these caps are oxidized, probably due to a leak and they measure weird in situ. It is good to have your guidance with this.
Just a quick update - I ordered the SMD caps and removed the ones on the RW board. A few of them had leaked, one caused more serious damage on a traces/pads it is connected to. I repaired the damage, now waiting for new caps to arrive in mail.
I think there was an element of luck that only two caps leaked substantially and that none of fine traces got damaged. I inspected and tested the close by vias and the other side of the board, seem to be ok.
Unfortunately I don’t have ultrasonic cleaner, but I thoroughly washed and scrubbed the board in IPO. It is a densely packed two sided PCB and I’m aware that many things can go wrong. Keep my fingers crossed.
In case I manage to sort out problems with electronics, I do intend to service the transport. You mentioned 3 plastic gears, but I can see only the motor gear available in DCC Museum Shop. Are the other two gears available? What other parts are available for 4th gen transports besides the motor gear and capstan belt?
I see some gear sets offered on ebay.
Are they any good?
Hi,
These should work for sure.
I guess it would make sense to replace all 3 gears and the belt in one go. Anything else to be serviced in the transport except cleaning and lubing it?
I am still waiting for the caps to arrive to recap the RW board. Hope that will go well since the board damage is not too extensive.
Just a quick update - RW board seems to function after repair and capacitor replacement, the front panel commands are responding.
Is there any other check I can perform before I order gears and belt?
thanks,
Vlad
hi, I need your advice. Unlike the other two translucent plastic gears, the idler gear does not show any damage but I’d like to replace it given the damage to other gears. The kit I purchased has the idler gear, but I am a bit puzzled with the way the idler gear is mounted and how to remove/replace it. What is the proper way to replace idler gear without risking any damage to the fragile plastic shaft? I managed to remove the idler gear assembly, but the plastic axle seems to be one piece. There is a YT video that mentions some kind of interlock between the shaft and the rest of the assembly, but I don’t see it and don’t want to break anything. What is the trick here?
I managed to resolve the issue. Use a caliper pointed jaw between the gear and the base of the black lever assembly and gently pry the top disc off.
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hi guys,
I have a small problem - the plastic gear that fits on the rewind/open/close motor shaft is slipping because the hole is not tight enough. I tried fixing it with crazy glue, but the motor steel shaft is polished and the glue does not stick to plastic inside the gear hole.
What can i do to resolve this problem?
thanks,
Vlad
Resolved. Used a a few small strains of cotton fiber between metal shaft and plastic gear. The gear is no longer slipping and the door is opening/closing fine.
Usually we glue this with Loctite.