CED VideoDisc and Player Discussion

[digicube]

No sound from L & R jacks and the audio button doesn't do anything when I press it. Here is a sample capture of Pink panther strikes again which I assume is a mono disc. https://drive.google.com/file/d/1kbcWV7HypmqT_mp153_66623C86yvWZx/view?usp=sharing

I wonder if this could be the solution. https://www.cedmagic.com/tech-info/repair-solutions.html#audio-gain-set-too-low

Found a similar thread on SGT250 here. http://www.cedmagic.com/forum/viewtopic.php?t=2658

I just downloaded the service manual for SJT models. Do I have a bad IC?

[jsdspif]

on my sgt200 and sgt250 I had bad audio demodulator ic's. I don't remember now but there were 3 legs of the ic that need to be at 3.3 volts and the bad ones won't have that voltagepresent. I think the sjt400 service manual (or one of the free ones) has the voltages that are supposed to be present at the ic's. When I did mine I put sockets in just incase the replacements would go bad (and also because it's pretty easy to fry the ic's with too much heat) John at CEDatum said the ealier chips were prone to failure and the ones he sells are more dependable. I'm going with at least those chips do seem to go bad.
Also you may try hooking up coax (if you have a tv with an analog tuner) and see if you get sound and/or chck the solder joints of the rca jacks. After I repaired the stereo board in a player it quit working but coax worked and I checked and could clearly see the solder joints were broken at the rca jacks. I guess they were about ready to break and the stress of monkeying around with the board broke them completely?

also also........see my swapping stereo boards topic that just got replied to.

[digicube]

No sound on RF either. Does this mean I also have bad audio demodulator ics?
What about the audio button on the front panel? Is it bad that it doesn’t do anything when I press it?

[jsdspif]

i would say for starters u3601 ic is bad ,but check it. I posted pins 1,2,and 3 are supposed to have 3.3 volts but I was so confused at the time I now wonder if those are the correct pin numbers? I believe they call that chip fm demodulator and there is another one of them in the stereo section of the board. On one of my players with no sound I replaced that first one and then had mono sound and replaced the other one and got stereo sound. But,of course,thouroughly check. One nice thing that check can be performed with just a volt meter.

[digicube]

Here is the service manual for anyone who needs it. https://drive.google.com/file/d/1en-ZzFSliwqPJ2lrZMkXh9nCFjpo7VX8/view?usp=sharing
On page 33, it list the ICs. Sounds like I need these ICs replaced.
U4101 audio demodulator
U4102 audio demodulator

What about these ICs?
U3501 RF modulator
U4300 Audio matrix and buffer.

[jsdspif]

the sgt 's i worked on are different in that there's a "main" board that has everything for the mono side and a seperate stereo board that makes it stereo so it seems like some numbers of ic's did get turned around. I'd have to do some in depth study if the service manual you have lists voltages at the pins of the ic it's like 2 or 3 pages no skip all that. I have to leave now but when I get a chance I'll try to figure things out. Seems like both chips were called fm demodulator and in the sgt one was on the mainboard and it sent signal to the rf portion and to the stereo portion and then the same chip on the stereo board made left and right audio. I think?? I'm not sure when i did those. The date would be the date of my swapping stereo boards (or what ever)

[jsdspif]

I'd start with the U4101 audio demodulator
U4102 audio demodulator pins 1,2,and 3 should have about 3 volts. I haven't done any work on the boards of the j series players other than just checking things because the 2 players I have opened were working. On the g series one of the audio demodulators is on the main board and one is stereo board but on j series it's more of an audio section of the board because everything is on the main board. After checking them out ,yeah,maybe I'm not sure what those other 2 ic's are. I just know on the main board of the g series that audio demodulator is 716khz and on the stereo board it's labeled audio demodulator 905 khz