Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives
Support This Site: Contributors :: Advertise


It is currently Dec Mon 09, 2019 3:26 am


All times are UTC [ DST ]





Post New Topic Post Reply  [ 2 posts ] 
Author Message
 Post subject: Eico 460s Solid State Oscilloscope - Schematic?
PostPosted: Nov Tue 12, 2019 3:35 pm 
New Member

Joined: Nov Wed 06, 2019 10:54 pm
Posts: 4
Hello,

I'm relatively new to electronics repair. I've always had a fascination/interest, but just recently found some YouTube channels and started learning circuit theory. I was given an old Ampeg tube amp, that i've been working on repairing. Then I came across this oscilloscope.

It's Eico 460s Oscilloscope. Apparently, it's a solid state rendition of the 460. I found post about an identical one here and got a few pointers about where to start:
https://antiqueradios.com/forums/viewtopic.php?f=8&t=351514

I'm looking for a schematic to help diagnose a fuse blowing problem. (Blows 1A fuse after about 5 seconds. No screen display)

Here are some pictures of the circuit board:
https://photos.app.goo.gl/xascMWtfmzGix8o97

I'm guessing that the 6 gray caps are the HV supply caps that I should check first?


Last edited by 4n6Days on Nov Tue 12, 2019 3:44 pm, edited 1 time in total.

Top
 Profile  
 
 Post subject: Re: Eico 460s Solid State Oscilloscope - Schematic?
PostPosted: Nov Tue 12, 2019 3:43 pm 
New Member

Joined: Nov Wed 06, 2019 10:54 pm
Posts: 4
I started this new thread because my previous post about it was in an old thread about a similar one. It seemed better to start a new thread. (Hopefully not a noob mistake...???) I wanted to copy the advice I'd gotten so far as to avoid duplicate info.

From Barry Bennett
Quote:
Troubleshooting a scope without a schematic is going to be extremely challenging. That said, blowing a fuse 5 seconds after startup sounds like a perfect candidate for old power supply filter electrolytics that need to be replaced. Of course, it could be about anything, but that's where I'd start while searching for a schematic.

If it blew the fuse instantly, I'd be more inclined to suspect a shorted rectifier or power transistor. The 5 second delay seems to indicate an overload rather than a dead short somewhere, but of course, no guarantee. Easy to check the rectifier or bridge, and any higher power transistors.

Second suspect for me would be something in the HV power supply, but you can pretty easily eliminate that as the issue by just disconnecting the power going to the HV section of the instrument. For this, you WILL need the schematic. H or V deflection would be the third suspect, and again you'd need the schematic.


From Tim Tress
Quote:
I suspect the capacitors in the HV power supply.

Another common scope problem is drifted resistors around the intensity and focus potentiometers. Check the voltages in that circuit at turn-on, and see if they go down.


Top
 Profile  
 
Post New Topic Post Reply  [ 2 posts ] 

All times are UTC [ DST ]


Who is online

Users browsing this forum: Codepug, POTS Don, TechyMechy, Thewasp, Tony L and 9 guests



Search for:
Jump to:  




























Privacy Policy :: Powered by phpBB