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Seeking assistance with Pioneer SD-1100 display issue

Ricktptman

Ricktptman

High Fidelity Enthusiast
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I've realigned this (to the best of my ability) several times after having noticed this anomaly.

Let me take a couple of things off the table first:

Does it need recapping? Most likely. I know of nobody local in whom I have sufficient trust to recap it front to back. My visual acuity (post-cataract) is such that I'm not inclined to take on huge projects that take long periods of time to complete. IF someone knows of someone along the mid-atlantic East Coast that I could take it to, please PM me. (It goes without saying that I'm not really interested in selling it, even if it was DOA.)
So here are the specifics:

1. I'm next to certain it's not the CRT. It gives every appearance not only being "good" but bright. I have a NOS CRT (keeping for that rainy day) that I switched out and I ran it just long enough to see the symptom reproduce itself on the NOS CRT, so back into sealed up storage it goes.

2. I've reduced the anomaly by letting it run for a couple of days (not my standard op, I rarely run it unless I'm in the room to ENJOY it) and it's now doing it just enough to approach being an annoyance. But it still makes aligning it difficult. With no external input the flat line will show some noise and some small jitter. But the vertical (up and down) jitter of the line is being very tough to null out.

3. As indicated, that horizontal flat line jumps up and down in the vertical/amplitude plane. Not when adjusted, just sitting there with no user manipulation. At first, because of the troubleshooting note found in the SM, I thought it was that CdS component, but I believe that's in the Oscillator section and not the display section. That section appears to work, but I'm not sure it's ideally aligned. I'll go back to that after I address this. (I very seldom use the oscillator anyway.)

If anyone has had this symptom (and more importantly has advice on how to fix it) please post or PM me. TIA.
 
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The V.H. amp unit AWX-032 is chock full of 2sc1312 transistors. Replace them with ksc1845's.
The board is in the top of the chassis, in the center. There should be enough slack in the wires to solder on the back.

the 2sc1312 pinout is BCE, the ksc1845 is ECB, opposite - so face it the opposite direction.




The metal can with heatsink 2sc627 can be replaced by ksc3503 but I'm hoping that it doesn't need to be.

Noisy transistors would affect differential amps that way (positional shifts in crt position).
 
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Ricktptman had reached out to me via PM and I requested a new thread here but he beat me to it :)
First of all there are very dangerous voltages inside this unit. BE CAREFUL!
I agree with Mark regarding the transistors being a more likely culprit than the caps. Other things to check: faderlube the vertical & horizontal pots on the front panel. Also look VERY carefully for bad solder joints or ones that were never soldered (I found one never soldered from the factory in mine, just a round copper pad with a lead sticking through it). You could also take the covers off, turn it on and tap the boards with something non-conductive to see if it causes the jumping. This would indicate a broken trace or bad solder joint or some kind of loose connection.
 
I've tried most of those and based on one of xlbee's previous posts I've been looking for cold/unsoldered joints. But I think it might be a dead spot on on one of the VR's. (One of the 4.7Kohms-VR4?-the one closest to wire wrap terminal 14, I'm not at it right now.)
I know I have one around here somewhere, the question is..."WHERE?". I've been tightening grounds, I (gently) cleaned the terminals on the CRT (that actually helped a little-much to my amazement) and there is a spot on the rotation of the VR where everything is very nearly flatline stable. But I can't adjust it so the vertical knob is at 12 o'clock...it's closer to 2 o'clock. It's a lot better than it was, but the dead spots (two of them) occur at the same place in the rotation and that's degraded from just being jittery when I first started. I'm still trying to get to the underside of it to clean it, but I think it would wipe clean through my having gently exercised it by now if that was going to actually work.
Thanks, gents...I'll be back when there's news.
 
Okay, here's the update on my SD-1100:
Most of the issue was this one bad VR (VR4) on the Vertical/Horizontal Amplifier board (AWX-032). It had one leg that was separated from the body up under the plastic rotary housing. Friction was the only thing causing it to have intermittent contact. I went through the entire machine cleaning and exercising functions I don't use all that often and it has, for the most part settled down now. I do see some very occasional drift upwards on the CRT, that doesn't seem to be related to ambient temperature. It's not a really big deal and it's not consistently noticeable. Is this likely caused by those 2SC-1312's? Otherwise, the alignment issues are, AFIK, solved. 20221214_202410.jpg
 
Ricktptman said:
Is this likely caused by those 2SC-1312's?
Click to expand...

Well, there are 8 of them in the horizontal/vertical amp circuit. Wouldn't be that hard to swap them out. Only 2 electrolytics on that board. I'd change those too while you're in there.

You could try disconnecting H in & V in (lift one leg of R1 and R20). If that makes the issue go away (line stays put) then the issue is before the H & V amp board.

Hmmm... if you disconnect both then you would have a stationary spot on the screen and the spot killer circuit might kick in... Let me think about this... The pot you changed was on the H circuit that pot should have only affected the width or the left/right position on the screen (somebody please tell me if I have this backwards). It's the V circuit that should adjust the amplitude of the wave and the position up/down on the screen.

So try lifting a leg of R1.
 
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Nope, the VR I replaced adjusts the Vertical. I think you're right about the spot killer. I'm on it...
 
Hello, Mark and fellow AK'ers. I've cleared time to take a run at this final part of the restoration. The VR solved some of it, but there's still some instability after it warms up. It's almost almost ignorable, but it's requiring semi-periodic readjustment on the Horizontal and I know that's not supposed to happen judging from my restored SD-1000. (That's a seriously underrated machine if you take the not having simultaneous Quad capability, rear inputs, and slightly harder-to-read meters off the table.) Here are the transistors I've received. The numbers don't match, but if Mark or someone can verify that these are KSC-1845FTAs, I'd appreciate it. Again, to confirm, I'll face these 180 degrees opposite of the originals because the pinouts are reversed. Yes? TIA, I'll let everyone know how it goes. Thanks for your patience.
 

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Several others on the old intertubes have received JC instead of KS, have used them and they have been fine. One thread said OnSemi had changed their packaging manufacturer.
 
SOLVED. Thanks to everyone for their help and detailed advice. Eight new transistors and there is no destabilization, nor any of its previous annoying behaviors. It took a while, but finally, it's done!
 

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Awesome. Congratulations! If you have seen what the SD-1000's are going for, it was well worth your time to resolve the issues. For the benefit of those who come after us, what transistors did you replace on which boards with which substitutions?
 
They were Mark's recommended KSC-1845s. I bought a bunch of KSC-3503s, but the 2SC-627s were fine. Thanks again, gents!
 
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