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 Post subject: Re: More Sony SDP-E800 issues & solutions +added exhaust fan
PostPosted: 18 Jun 2020, 03:14 
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allenwrench wrote:
Which outputs are you using, the analog or digital?


I’m actually using the six channel output and routing them to a set of Logitech 5.1 PC speakers (it's my cheap system for where I live right now). Once I get my broken Marantz fixed and get real speakers for it, the E-800 will become just an AC3-RF Demodulator and thus utilizing its optical digital output.
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 Post subject: Re: More Sony SDP-E800 issues & solutions +added exhaust fan
PostPosted: 04 Dec 2020, 07:40 
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So..... it has been about 8 months since I last spoke about my audio cutting out issue on this processor and I'm just going to be honest that the issue has never been fully resolved and I decided it was getting ridiculous to keep jumping the gun that I had finally fixed it. Thus, I decided to spend these last few months tinkering away and really trying to be patient and document all the changes I made to the unit and noting where the unit improves or gets worse in certain aspects. Anyway, what I am about to write in this post does not mean that I did finally fix the problem but I will say the unit has gotten impressively better to the point that I now feel confident that I can write up this update.

Here is timetable of the progress I made.....


4/13/20 - 7/15/20

This was right after I changed out caps C235 and C236 as noted in the last addendum of the first post. The overall experience I had with the unit for these three months was a combination of losing sound with or without a click on the relays. Also, I found that switching to the analog input and back would bring the sound back after a loss (vs. going between different digital inputs) so I felt that maybe I am having an issue w/ an input switching chip. However, there were times that the sound would disappear and any input switching wouldn't do a thing to fix it and @ that point I shut the unit down and then it would return. Later on, I also found that sometimes running the test tone after a sound loss would bring the sound back so now I was thinking the control IC was now an issue and that would be frustrating to verify. In any case, these issues were very sporadic during this three month test so there were times the processor was just on fire and never glitching and then suddenly it would just glitch continuously for an entire day. It was now time to tackle something new inside the unit to get this glitch under control.



7/16/20 - 9/19/20

I decided to tackle the Phased Lock Loop board and replace the two caps on it.

Image

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Just to get to the point, the next two months showed no noticeable improvement so now I was a little more confident this was not the issue. And the reason I was led to think the PLL board could be an issue was that I thought I heard a lot of the relay clicking coming from it but I was wrong in that assessment (I'll explain more later in the post).



9/20/20 - 11/13/20

My next approach was to focus on the A/D Converter chip and and replacing six caps in the general area. Here are the caps that I changed out....

Image

I focused on this area as I did start to notice some audio distortion issues when using the analog input and thought that maybe this had something to do w/ the audio lock issue as well. In addition, it appears that some of these caps were also directly tied into the input switching IC which I felt was still a possible issue. After I had them replaced, I tested the unit and it appeared to glitch even worse before the cap swap even to the point that the sound wouldn't come back until I shut down for a couple of hours and then it performed fine for the rest of the day. However, here is the weird part. The unit then performed fine for the next 35 or so days with only four occurrences in that time frame and I was really running it hard (having it on for up to six hours in a day at times). I was still not satisfied because it obviously still had the issues even though it was minimal. So.....



11/14/20 - 11/20/20

I went ahead and replaced five more of the caps in and around the AD Converter thinking that might really be causing the issue since I was pretty happy w/ the performance of the unit after the 9/20 cap replacement. Here are the caps that I replaced (kind of hard to see the red markings; my apologies).....

Image

The unit worked great for the next two days and suddenly the sound disappeared (can't recall if I heard a click or not of the relay) on 11/17 and basically never came back. It was functioning but I could not get any sound out of it at all and the relays completely stopped working. I tested the unit for the next few days to try and figure out this new issue as it never stayed dead like this before. I ran a test w/ the optical output of the unit to see if it could pass sound on it and unbelievably it was working fine passing PCM and DD from the Digital and AC3-RF inputs. Thus, if I could not fix the issue, it least the unit was still serviceable as an RF Demodulator. Now, the good news about this new dilemma did bring about a new perspective for me in that now it might be possible to finally find the real issue now that something was totally dead. And that led me to this now.....




11/21/20 - present

So.... I went back to the service manual and decided it was time to really look @ the relay circuit to see if I can follow it back to where the problem could be. I still felt the relay itself could not be the issue since this unit uses three of them to control the six analog audio outputs and it would seem pretty impossible for three relays to all die @ the same time. Thus, I found that all three did go through several transistors that ultimately lead back to IC150 which is the control IC of the unit. After looking @ the schematic of how this chip functions, I kept thinking there has to be something besides the chip itself that could be causing the issue and eventually I started to consider a ceramic oscillator (X-103) that was tied into pins 82 and 83.

Image

I did a lot of research to see if these types of oscillators had issues as they aged but I could not really find any relevant information. So at this point, I had nothing to lose but to take the unit apart again and examine this part. My plan was to desolder it from the board to see if maybe I could take it apart and look for anything odd. I ended up finding that I had previously reflowed it sometime back and the solder actually looked a bit clumpy to me. So I thought, maybe my last reflow job actually caused a cold solder connection and @ that point I decided to remove all the solder and resolder it from scratch. I had the unit re-assembled & power up and unbelievably I started to hear the click of the relays again. This was definitely great progress as I never had one fix that went from dead to alive in all the previous attempts. I have been testing the unit constantly since that time and I did have one occurrence of the sound going off but I'm not sure if it was really the unit as I was fumbling around w/ the wrong remote and accidentally switched an input on my TV that then created a mis-lock on the processor that brought the sound back.

Anyway, the big question now is if the unit is really fixed or not. The answer is still - "I don't know". I'm just waiting again for another glitch but so far this has been the most promising outcome in a long time. If I can get another two weeks or more of zero glitching, I'll feel more confident the issue is finally nailed down. If the glitch returns and the issue does tie into the relays clicking off again, I am contemplating replacing that X-103 oscillator (they are pretty cheap on ebay) since that does appear to be a key problem based on this latest repair. Also, in respect to all the caps that I did replace (29 all together + 1 super cap), I'm sure some of them were causing the audio distortion as well as the occasional loud bang on the speakers that did pop up along w/ the relay glitch as I have not had these types of issues since the last of the caps were installed (but we'll see).

Countdown to two weeks for the next update :roll:



Addendum for 12/8/2020 >>>>>> Didn't think I'd do a quick update so soon but tonight the unit did lose sound w/ the click of the relays going dead again. I tried to get the sound back by running the test tone and changing inputs but nothing worked. I ended up shutting down the unit for about 40 min to give it a break and the sound did return after that and was great for 4.5 hours until I shut it down for the night. It definitely sounds like my ceramic oscillator could be the issue so I placed an order for a pack of them that hopefully will arrive in two weeks. So, the update will be delayed but I'll keep checking the until then.



Addendum for 12/27/2020 >>>>>> The unit had another incident where it went completely dead on the relays again and nothing would get it going again so I thought it was now time to replace what I felt could be a bad ceramic oscillator. I opened up the unit and as I was unplugging the CN-102 and CN-101 ribbon cables, I decided to just plug them back in and power up the unit again. To my surprise, the unit's relays started to click again and now I think the issue might be caused by something on the display board. I did end up replacing the oscillator but due to some confusion on verifying its functionality I quickly put back in the old one (it appears that this unit needs the back panel screwed back in as it will malfunction due to what appears to be a grounding issue). In any case, I re-soldered a number of connections on the display board including the CN connectors and a few key components that could have cold solder. The unit has functioned fine since this time so we'll see how it goes. I plan to still replace the oscillator if the unit goes out again.


Last edited by ldfan on 01 Jan 2021, 05:28, edited 12 times in total.
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 Post subject: Re: More Sony SDP-E800 issues & solutions +added exhaust fan
PostPosted: 04 Dec 2020, 16:35 
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Nice write up. This is echos pretty much my experiences with board repairs. I'm always surprised and elated when I fix something that has taken a while to debug and then that is followed by the "I hope it stays fixed" feeling. :lol:
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 Post subject: Re: More Sony SDP-E800 issues & solutions +added exhaust fan
PostPosted: 18 Jul 2022, 09:09 
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Well.....it has been now 19 months & change since my last update regarding this processor repair and recently I had to tackle a totally different issue. Check out my YouTube video below to see what I was dealing with....



So as you can see, my VFD (Vacuum Fluorescent Display) was having this shimmering/flickering issue. My first thought was that the VFD lost its seal and now it was probably shot and I would have to live with it (or get another E800 display board which means just getting another E800). Anyway, I did some research to see if the issue could be something else and I eventually found a posting about someone trying to fix a flickering issue on a Sony DAT machine and he diagnosed it down to a shorted zener diode in the power supply.

So at this point, I focused on the transformer section to see if there was any odd readings and I really couldn't find anything that seemed odd (especially if the rest of the unit was working fine). I then decided to measure out of the power coming from connector CN-101 (connects between main board and the display board). Here is a pic for reference....

Image


There is a 32vdc line that is the main supply for the VFD on pin 3 and I measured 39vdc so I assumed that maybe this is an issue of too much power. I looked up the path of this 39vdc line and was able to follow it back to Q-901 located here on the main board....

Image


The reading I got from this transistor was the same 39vdc so I then removed the main board from the chassis to inspect the underside since there were other parts associated w/ this transistor. Upon making some quick readings w/ the voltmeter, I did find a defective part and it was D-903 (a zener diode as was mentioned by the person writing about his DAT machine) and it was shorted completely....

Image


And as I mentioned in the pic, the issue appears to be voltage escaping into the GND line and this must be the cause of the VFD shimmering (I thought that maybe the zener diode's function was to bring the 39vdc down to 32vdc but it turns out the 39vdc is normal for the VFD circuit).

Anyway, I researched the part that I needed but could not find an exact match. I went with a zener diode that appears to be able to handle more watts but was rated the same for voltage. I de-soldered the old part and cleaned up the solder pads to get the surface flat to make installation easier for the replacement...

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And now the new part in place...

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I reassembled the processor and glad to see the display was back to normal again :thumbup: .....





Moving on... let's discuss the reason I started this topic in the first place which was always about the audio cutting out. Well, after these 19 months the issue has never been completely resolved. The typical issue I get now is that I will lose sound on the unit on all channels approximately every 20 days or so. Sometimes I can resolve this issue by doing things like changing inputs or hitting the test tone button and it's good again for either a few days or few hours later. However, sometimes it just completely stays dead and won't come back until I open it up and fiddle around inside the unit. And so here is my new observation on what I think could be the issue now. Let's go back to this connector.....

Image


So, what I would do is fiddle around with this connector (CN-101) and it always comes back after I re-seat it. However, I can't replicate the issue with any consistency as fiddling w/ the connector after the re-seat won't kill the processor again. So after much thought, I am thinking that maybe the issue is in the plug and I am dealing w/ some problem w/ the springiness of the pins inside that possibly aren't applying enough friction on the ribbon cable. I did make an attempt to push out the pins from above but I'm not sure if it worked or not (I may need to remove the plug first and work on it from below). Also, another consideration is that the ribbon cable might also have some oxidation issue and maybe rubbing something like Deoxit on it could improve conductivity (remember, it appears to have a good connection for 20 days and then it loses it which could be an oxidation build up in that time period).

Hopefully I'll get around to it sooner than later.
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