M90 motor and capacitor question.

[blu_fuz]

So the M90 im working on is missing a 22uf 50v 220uf 16V cap across the terminals of the cassette motor.

First question is why, why would someone cut motor wires and remove that cap?

Second question, is that the correct information for the missing cap?


Thanks!

Here is the motor that im working on.


This is what it should look like.


Here is the schematic:

 

[Michiel]

Your photos shows the capstan motor, but you point to the reel motor on the schematic. The capstan motor needs 220uf, 16V according to the service manual.

 

[blu_fuz]

Ok. Woops. You are right, this motor drives the big flywheel.

 

[Michiel]

Yeah, that's the capstan motor

 

[blu_fuz]

Thank you.

Any idea why someone would take that off?


I dont have that value cap here but i do have a 220uf 10v, is that able to be used or should i buy the one it needs?

 

[Michiel]

Just a theory. .. Maybe someone noticed a motor hum and tried to replace the cap. But didn't finish the job. Most likely because the hum wasn't eliminated by the new cap.... Because the hum was caused by a badly earthed shield between the motor and amp board.

Using a higher voltage cap is no problem. Don't use a lower voltage as it might blow. So try to find an other one!

 

[Superduper]

You cannot use a 220/10 cap to replace a 22/50 cap. First even if the additional charge time is not an issue, the voltage certainly is. The lower spec cap might literally blow up or expand like popcorn.

Now, that being said, the cap in the picture looks bigger than a 22uf. I bet if you look closely, it's actually a 100 or probably 220uf. If so, you can use a 220/16, 220/25, or anything that is rated at 16v or higher.

Lastly, most BOOMBOX motors don't have that cap. It's possible that it's a replacement motor.

 

[Superduper]

Oh and that cap's purpose is most likely to stiffen the power rail and not for hum or interference. The bypass (small ceramic cap) is more for that purpose.

 

[blu_fuz]

Yes Norm. I was only asking if i could use a 220uf 10v in the position of the 220uf 16v that looks to be missing. I did remember from my panasonic re-cap that i need to keep the uf rating the same, but there was some lee-way for using a cap with a different voltage (couldnt remember if i could go +/- voltage).

I dont have that specific cap in stock, thats why i asked.

If it is a replacement motor, or not, will it be ok to hook this back up with no cap and run it? I had to order the correct cap, i only have 220uf 10v here.

 

[Superduper]

I'm sure it will work fine without it but in the long run, it's better for it to be present as it gives the motor a little extra umph to get over those humps like when mechanism is resetting. I'm sure I have it somewhere but I would have to search for my parts stock. Alternatively you can simply get one at your local radio shack. You have those in your very remote part of the country, right? Lol.

 

[Superduper]

Or.... although I normally don't like reusing old components, you got lots of parts pcb lying around right? Scavenge one from your old boards. It's a common enough value.

 

[blu_fuz]

I looked through the lasonic pcb i have at home and i didnt find one. My M70 pcbs are all boxed up at work.

I am on baby duty today, so no running to rad shack for me lol.

Ill get the cap in there when it shows up. Other than that, i should be just about ready to put this M90 back together tonight.

 

[blu_fuz]

Thanks for the info guys.

 

[blu_fuz]

I rebelted the deck. Soldered the wires back to it and its still dead. Doesnt click, rotate, hum, nothing.

 

[Cpl-Chronic]

could be something simple? LIke you forgot to attach the bus cables to the deck itself? I've done that & freaked out untilo I found it once.

Cpl

 

[blu_fuz]

The deck has never worked since this member bought it. There were unhooked connectors and wires taken off the cassette motor. Maybe the last owner fried it, I have no idea why it was messed with in the first place.

 

[Superduper]

Probably time to consider testing those 4 fusible resistors.

 

[blu_fuz]

Oh yes , those buggers.

 

[blu_fuz]

Uhhhh is this M90 missing one of the fusible resistors on this board???

 

[Superduper]

When I expand all I see is a pixelated maze. Besides the resistors are on the flip side aren't they?