blown component on Sony MP-F75W

[feltel]

I was renovating one of my Compact Macs floppy disk drive. Its gear broke in pieces. I took the chance to clean and grease it. Upon reconnect it i heard a short electrical crackling. I imeadiately shut down the machine. Upon inspecting i found an broken/chipped component on the disk drives PCB. Q4 does not look right. I dont know how this could happen. I held the drive in my hand and nothing was shortening. Anyway. Is there anyone who can tell me what component this? It would be a shame to throw away the drive due to a small component failing

 

[s_pupp]

I can’t answer the question, but please don’t throw away the drive. I’m sure plenty of us have spare boards at a reasonable cost that you could use to replace the bad one, or would be willing to buy your broken drive.

 

[feltel]

Rest assured I wont throw away the drive at any time soon.

With the help of a picture search I could validate that the blown component is/was a transistor with a "BV5" marking. I'm currently checking suppliers for a suitable replacement component.

 

[LaPorta]

I did this once accidentally. I did find the part. Believe it or not this was something like three years ago…and I still haven’t replaced it! I do, however, have the parts and can tell you what it is if you can wait until I get home late this evening.

 

[jmacz]

@LaPorta were you able to find out what the component was? I just came across a F75W with the same component blown. Looks to be a transistor but not sure which type.

 

[feltel]

It should be a "2SB624" which goes on Q4. I ordered a bunch of these on AliEx and hope to get this drive working again. While Q4 blew up I tested the drive without the eject motor in place. Could this be the root issue of blewing up Q4?

 

[8bitbubsy]

I have also blown this exact part, it connects to the eject mechanism. My guess is that something jammed the eject motor so that it used too much current (or that it was connected wrongly?). In my case, replacing it with the same part from a broken drive made it work perfectly fine again.

 

[LaPorta]

@LaPorta were you able to find out what the component was? I just came across a F75W with the same component blown. Looks to be a transistor but not sure which type.

Really sorry, I have had some family emergencies of late. I will see if I can nail it down tonight.

 

[jmacz]

Really sorry, I have had some family emergencies of late. I will see if I can nail it down tonight.

Sorry to hear, I think we got it sorted on the thread. Hope everything is ok for you.

 

[LaPorta]

Thank you, things are going better. Yes, indeed, that was EXACTLY what I did as I now remember: tested the drive without the eject motor in place. Not only did I take out Q4, but Q9 and R48 as well. Q4 and Q9 are the same. Q4/Q9 are Zener Diodes, 3.0 Volt 0.3 watt.

https://www.mouser.com/ProductDetail/Vishay-Semiconductors/AZ23C3V0-E3-08?qs=KP8Io%2FXyE5QzLGm4agF0YA%3D%3D

 

[CharlieFrown]

does this drive work without eject motor? I have bunch of these with broken motor gears.

 

[feltel]

My drive did blew up components when "used" without the drive eject motor attached.
But this could be pure coincidence.

 

[techknight]

Thank you, things are going better. Yes, indeed, that was EXACTLY what I did as I now remember: tested the drive without the eject motor in place. Not only did I take out Q4, but Q9 and R48 as well. Q4 and Q9 are the same. Q4/Q9 are Zener Diodes, 3.0 Volt 0.3 watt.

https://www.mouser.com/ProductDetail/Vishay-Semiconductors/AZ23C3V0-E3-08?qs=KP8Io%2FXyE5QzLGm4agF0YA%3D%3D

yeah Q4 is the high-side VCC switch for IC3. Whatever happened with IC3 blows Q4.

Q4 and Q9 are NOT zener diodes! They are transistors.

Q9 shorts CN3 1 and 3 together when enabled. R48 is a pullup to keep the transistor turned OFF when not asserted by the control circuitry.

 

[LaPorta]

@techknight Thank you for that. I’m not sure how I got the incorrect information…but that was two years ago.

 

[techknight]

@techknight Thank you for that. I’m not sure how I got the incorrect information…but that was two years ago.

Ive never personally ran into it before, at least not yet but just looking at the pictures I can map the circuit out in my head pretty much right away and see whats going on, luckily.

 

[feltel]

I'm not that deep into electronics, at least at that level. Could you explain why Q4 blew up when the eject motor was not attached? It blew within a fraction of a second right after turning on the Mac. I could not even try to use the drive at all.

Why did Sony design it that way. Its not very fault "tolerant".

 

[feltel]

I want to bring this thread to an end. I replaced the Q4 diode and the drive works like a charm.