LG OS-5060a

[Scope_Newbie]

Hi folks,

I just got an LG OS-5060a oscilloscope and noticed when picking it up to move it that the back of the unit was very very hot. I took the cover off and found several power transistors mounted to the chassis by screws (I marked them with an "H"). I'm aware these types of transistors can run quite warm but I've never experienced any that will burn you silly if you just quickly tap it with your finger, Yeeeeeouch! These are hotter than bloody hell. Is this normal? (Please if anyone has a service manual for this scope, send it to me, thanks).

The component numbers are:

SEC 721 D288-Y and SEC 714 C2335-Y

Any help is surely appreciated and thanks for the great forum

 

[Resqueline]

Unless the plastic insulators under the screws are showing signs of melting I wouldn't worry too much. Check if the screws are resonably tight.
If you carefully put a small drop of water on them does it boil off quickly?
The steel frame isn't a very good heatsink, so it might be just the way it is designed.
The chip inside can stand 150 degrees Celsius on a permanent basis and I've seen such transistors melt the solder on their pins (>183 degrees Celsius) and still work.
One of them is a 2SD288 and the other is a 2SC2335 btw.

 

[Scope_Newbie]

Unless the plastic insulators under the screws are showing signs of melting I wouldn't worry too much. Check if the screws are resonably tight.
If you carefully put a small drop of water on them does it boil off quickly?
The steel frame isn't a very good heatsink, so it might be just the way it is designed.
The chip inside can stand 150 degrees Celsius on a permanent basis and I've seen such transistors melt the solder on their pins (>183 degrees Celsius) and still work.
One of them is a 2SD288 and the other is a 2SC2335 btw.

Thanks for the quick reply. The insulators are rubber. I put the cover back on and I'll not worry about it after reading your message. Next time the cover is off, I'll use a moist Q-Tip to test it.

I'd love to have a service manual for this thing. I've looked all over the internet but can't find anything. I'm hoping there is a scope guru here that has one.

 

[Resqueline]

The insulators you refer to are the sheets between the transistors and the "heatsink" but that's not the ones at risk of melting that I were referring to; those are between the screws and the transistor.

 

[TucsonCowboy]

If you still happen to be searching for a manual, I downloaded one from Jameco's On-Line catalog. It's a very neat and clean PDF image; not scanned from a printed copy.

 

[Tod Yampel]

If you still happen to be searching for a manual, I downloaded one from Jameco's On-Line catalog. It's a very neat and clean PDF image; not scanned from a printed copy.

I also got the same scope. It is working fine but I would still like to have the service manual for it. Searched the Jameco site but could not find it. Please post it or email it to me.
Thanks in advance.
Tod Yampel

 

[Jim Stafford]

I also got the same scope. It is working fine but I would still like to have the service manual for it. Searched the Jameco site but could not find it. Please post it or email it to me.
Thanks in advance.
Tod Yampel

I was just on Jameco's site and could also not find anything on the service manual for the OS-5060A scope. If anyone knows a place to get one, please advise.