Yamaha YP-D6 Pulsing Speed - Rebuilt - Parts List - SOLVED YAAAAYYY

[Johnny_Law]

EDIT NOT QUITE SOLVED: Issue with all three pots & pot adjustments but came back aaaagggghhhh

EDIT2: Was the diodes!!!

This wasn't holding speed so I cleaned the pots and put in all new electrolytic caps & transistors, and it still won't hold speed. But now, it pulses fairly aggressively as if I put in the wrong transistor somewhere. Yeah, the new parts seem to have made it run worse.

So I bet I messed something up somewhere. I double and triple checked my transistor pin orientations and they all appear correct three times over. So I'd love it if someone could verify that my parts list is correct, especially the transistors. Maybe I goofed with the wrong parts. Maybe I got my NPN and PNP wrong?

One thing that surprised me is the pin orientation of the KSA733YTA on the data sheet (E B C) so I had to install them basically vertically into the TR5 - TR9 and TR11 & TR12 spots. I trust the data sheet but thought I'd mention it. (Edit: Get center collector ones!)

Thanks in advance!

Power Circuit Board C103 470/50 Mouser 647-TVX1H471MCD
Power Circuit Board C101 470/35 Mouser 647-TVX1V471MCD
Power Circuit Board TR101 2SC789 Mouser 512-KSD526Y
Power Circuit Board TR102 2SC458 Mouser 512-KSC1815YTA
Servo Circuit Board TR1, TR2, TR3, TR4 2SD571(K) or (L) Mouser 512-KSD1616AYTA NO! THIS IS WRONG: USE 512-KSC1008CYTA INSTEAD
Servo Circuit Board TR5, TR6, TR7, TR8, TR9 2SA733(P) or (Q) Mouser 512-KSA733YTA: ORDER KSA733CYTA INSTEAD, THEY ARE CENTER COLLECTOR!
Servo Circuit Board TR10, T13 2SC945 (K) or (P) Mouser 512-KSC2383YTA
Servo Circuit Board TR11, TR12 2SA733K Mouser 512-KSA733YTA: ORDER KSA733CYTA INSTEAD, THEY ARE CENTER COLLECTOR!
I would also recommend replacing the trim pots - but I don't have the part #s ...

I didn't snap pics / videos yet but can add them to help diagnose.

 

[Nashou66]

What are the HFE ratings on the KSA733's?

your old parts were P or Q rating that on their data sheet falls between P( 135-270 ) and Q ( 200-400 )

The new parts would have to be either Y ( 120 - 240 ) or G ( 200-400 )

I would have tried to match the HFe if possible .

That might be an issue but not 100% sure.

What about the caps?

Did you follow schematics, the printed circuit board markings or visualy of how the old parts were installed? I ask cause sometimes
either the Schematics or the printed circuit board can be incorrect. So with vintage gear I follow how the original parts were installed.


Nashou

 

[Johnny_Law]

Thank you - the new KSA733s have an HFE gain rating of Y (120-240). Fingers crossed that would work for both the P or Q (TR5 - TR9) and K (TR11, TR12).

The PCBs are actually very well and clearly silk screened and the labels all matched the manual 100%. I installed the new components according to the schematic value, oriented to match the old components in agreement with the PCB and the manual.

HOWEVER - Two components coming off the board differed in values from the manual. One in a little way (10uF / 25V caps came out of the C12 and C18 spots on Servo Circuit Board, while the schematic called for 10uF / 16V caps which went in), one in a big way (a 4.7Uf cap came out of the C8 spot on the servo circuit board, while the schematic called for a 47uF cap which went in).

I'll check everything again and take some pics.

 

[UncleBingo]

i always go with what was in there in a stock unit over the service manual list unless a service bulletin is involved.
2sc 458 sub possibly a KSC1845 is better fit for dissipation in power supply app?

 

[Johnny_Law]

I may have a 4.7uF cap I can put in and see if that fixes it! Worth a shot.

 

[Johnny_Law]

And I will look for a KSC1845 too.

Question - does the "K" HFE rating mean a gain of 300-600?! If so, maybe I've mis-matched TR10, TR11, TR12, and TR13 all to Y-rated replacements.

 

[Nashou66]

And I will look for a KSC1845 too.

Question - does the "K" HFE rating mean a gain of 300-600?! If so, maybe I've mis-matched TR10, TR11, TR12, and TR13 all to Y-rated replacements.

That could be it......



And going up in voltage wont hurt and sometimes is needed. I always try to up in voltage if the space allows for it.

Nashou

 

[Johnny_Law]

Here's a video of what it's doing along with some pics of the two circuit boards.

 

[Johnny_Law]

Edit: This was not solved.

[not] Solved - Suspecting bad soldering, I wiggled the KSD1616AYTA in TR4 and it was HOT to the touch! The leads were definitely correct - ECB as you can see in the pic - but they must be the wrong transistors for the job.

So I put the original 2SD571Ls back in and we're back in business.

I fished the original 2SA733s all out of the bin and tested them - sure enough, more than one of them had opened up. So those must have been the initial culprit after all (well, maybe the caps too).

Thanks for the help!

 

[Nashou66]

good detective work !!!!

Glad its back in business!!!

 

[marvelus10]

Mine also had those same discrepancies between caps on the servo board and what the manual called for. I went with what was on the board, my problem is now fixed.

 

[marvelus10]

Well my problem came back, I only replaced the caps on the servo board and cleaned the pots though. Its not as bad as before, now it just does it for a few minutes when I first put a record on, almost as if once its warmed up it plays fine.

 

[Johnny_Law]

Edit: This was also not solved.

So I put the original 2SD571Ls back in and we're back in business.

This didn't last long, speed issues came back. So I replaced them with KSC1008CYTA (first post updated), and NOW the speed is rock solid. Whew.

If I were to fix another one of these, TR1-TR4 would be the first place I'd look.

 

[Johnny_Law]

Was rock solid for a month - not any more. Now, every so often, it will speed up and stay at a higher speed, and then after about the same time interval, will slow back down to the speed it was set at before.

I suppose it could be that (a) one of the few things I left underneath has gone bad; (b) the motor needs to be lubricated; (c) the bias pots got dirty again; (d) something else?

 

[Johnny_Law]

Bias pots needed another cleaning - it's back! Hopefully for good.

 

[Johnny_Law]

That was short lived. Here's what it's doing now.

 

[Johnny_Law]

I put back in a 4.7uF cap to match the one I removed at C8 (instead of the 47uF cap I put in per the schematic), but same symptoms. The speed is both pulsing continuously, maybe twice a second, and also gradually drifting either faster or slower.

(Edit: To follow up, there was also a 4.7uF cap in my other YP-D6. Safe to say 4.7uF is correct, it seems the service manual is inconsistent.)

I took apart the motor and it seems fine, so put it back together.

Running out of things to check. Although I have not yet taken out of circuit and measured all the resistors and various diodes.

 

[Johnny_Law]

ALRIGHT ... and the winner is ... (I think) a bad transformer!!!!

It's really nice to have a working YP-D6 too so I can compare them.

First, here's the voltage out of the power supply on the good one:

Now here's the same voltage reading on the bad one. Look at how it is pulsing.

So after testing everything in the power supply (transistor and orientation, rectifier diodes, zener diode) and finding it all to be good, I put my leads on the orange wires coming off the transformer. They are supposed to feed a constant 24V AC. Here's what I found.

I measured the same on the good transformer, but didn't video it. It was constant.

I have a used working transformer on the way, and am crossing my fingers!!!

 

[Johnny_Law]

Got the output from the power supply back to constant. I put the new transformer in only to find out it was TR102 causing the problem the whole time. Now the power supply source is rock solid DC voltage.

(WHY was TR102 causing the AC voltage input from the transformer to oscillate? Heck if I know ...)

However, the speed still pulses. At least I've narrowed it down to the servo circuit board. Will look in detail tomorrow.

 

[OMGCat!]

Got the output from the power supply back to constant. I put the new transformer in only to find out it was TR102 causing the problem the whole time. Now the power supply source is rock solid DC voltage.

(WHY was TR102 causing the AC voltage input from the transformer to oscillate? Heck if I know ...)

However, the speed still pulses. At least I've narrowed it down to the servo circuit board. Will look in detail tomorrow.

The transformer isn't regulated so if the offending part is causing loading and unloading of the circuit (like sudden speed changes of the motor) you'll see the voltage go up and down.
That sounds like a pain to troubleshoot but good job on getting it straightened out!
How did the lubrication in the motor look when you took it apart? I was thinking I might need to inspect and lubricate the motor on my YPD71 but it's really in there and if yours still had good lubricant mine would likely be ok as well I'd think.