Sanyo Betacord 3900II - Videokarma.org TV - Video

tvcollector · #1 11-21-2011, 04:40 AM

I picked up a Sanyo Betacord 3900II at the local flea market for $10.. I got it home and loaded a tape, and played rew and ff perfect with no worn belt issues.. Appears to be hardly used and there is no corrosion and no dust in the machine, almost looks new.. I noticed when playing a tape the head motor keeps shutting on and off.. I thought maybe a bad electrolytic maybe the issue, So I replaced a few of them on the servo board, where the head drum speed circuit is located and did no good.. I tapped on the circuit board, seem to not make any difference, I also tapped on the head drum and moved wires around and also seem to make no difference.. I was wondering maybe someone would know what would be causing this? Of course when the drum is spinning around the correct speed, the picture will appear until the heads slow down to a speed that's unreadable..

Here's a video that shows the problem:

http://www.youtube.com/watch?v=iJek56O2GsU

Ed in Tx · #2 11-21-2011, 08:53 AM

That is a weird problem. Like the power just goes away to the head drum motor. Looks like service manual and oscilloscope troubleshooting time to me!

tvcollector · #3 11-21-2011, 09:31 AM

If I had one.. When I get the finances to buy some testing equipment.. Also I would need to purchase a service manual for that model... I'm thinking maybe it could be a power supply issue, but if it was, I would think it would be causing more problems than just power to the head drum motor..

Electronic M · #4 11-21-2011, 12:10 PM

This is probably a long shot on a top loader, but check for surface mount lytics. My sony super beta had one on it's capstan board that would make it randomly stop, and untill I changed that cap I had to manually give the thing a nudge to restart it every time it would quit.

tvcollector · #5 11-22-2011, 08:24 AM

Seeing how my budget is tight right now. I was testing the electrolytics by taking a new one and touching the leads to each one to see if the drum would start spinning. One of them seem to have an effect sometimes when touching the leads, but that's on of the one's I replaced.. I touch the solder joints with my thumb, and in a certain area where a bunch of resistors are located makes the head drum move, along with the tape speed going real fast. I don't see any surface mounts, I do see alot of other caps which don't have any value labeled on them..

***Eric H*** · #6 11-23-2011, 10:58 PM

The motor sounds really noisy, my guess is the motor itself is bad?