Studer A730 CD player spins backwards

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#42
So.... to define the question radically, I took courage! I removed the 2 eproms IC3 and IC33 from the non-working Studer and mounted them on the other working one.🥶
Everything works perfectly🤩 so both eproms are fine and the problem on my Studer A730 is another.🙄
 
#45
Then it must be something with motor driver or servo ic,but looking at photos,i think it's old technology device, and servo may be realised by several discrete ics Ok, i'm looking at servo schematic in service manual, p163, looks like signal for motor drive formed by IC6 , but have not found a spindle driver yet. J3 pin3 , named VM, compare voltage of bad board with good one and reportt.
 
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#46
Riukyge said:
I'll start by saying that I've tried the entire upper "half" of this one that I'm restoring (for me) in another fully functional Studer A730 of mine: the entire upper half works perfectly, so the problem is in the mainboard of which I've already completely renewed the power supply section.
Click to expand...
I also started changing many ICs, both of the servoprocessor and the controlprocessor... I'm getting more as well... as soon as I can find them...
 

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#47
By just replacing , you are wasting money and time . For me it\'s more interest in studying schematic ,and checking voltages ,and trying to understand what's wrong . Especially , if you have two players , you can compare voltages at several testpoints and find differences ,then study this area more deeply . Fault can be anywhere ,even resistor come bad ,or track broke near connector ... maybe not even ic .
 
#48
Have you tried to exchange servo boards between players ?
Still can't locate spindle motor connection ,motor driver in service manual .Maybe service manual is incomplete , and exactly whats needed ,is missing .Where are backward spinning motor wires connected ? What parts are associated with it ?
 
#50
So then probably motor wires needs to be traced ,and driver schematic drawn and reverse engineer ,to understand where fault is .One thing you can do now is to measure voltage on motor wires and check with supply voltages after voltage regulators ,if they show no shorts .Maybe in bad player someone attempted repair before ,and wired motor incorrectly . In my understanding ,spindle motor should run in both directions , reversed only for faster stopping cd , when eject during playback is pressed .Had SONY player with interesting defect ,pressing eject during playback ejected spinning cd, without stopping it first ! So logically think there should be a bridge driver , like in servo board ,for RADIAL motor ,where both motor wires going to driver outputs ,no one should measure short circuit to ground .
 
#51
Thmartin
I want to buy another programmer like yours (https://xgecu.myshopify.com/product...ash-emmc-bga153-162-169-100-221-tsop-sop-plcc), so I can better compare the results with yours (with checksum) and have a socket to place the prom more comfortable than the one I have now available with the programmer I just bought (I don't like it https://www.amazon.it/dp/B00K2VYBC0?ref=ppx_yo2ov_dt_b_fed_asin_title ). Since I also bought a new TBP28L22 prom, how do you recommend I proceed to copy and transfer the file of the one still mounted? Can I use the same programmer...? Very thanks!!
 
#54
Riukyge said:
Have you ever programmed a new TBP28L22, IC68 Studer 1.861.487.20?
Click to expand...

Why do you want to re-write IC68 ? 🤔

Anyway the TBP28L22 is not supported by the Xgecu programmer. (contrary to what I stated earlier, should have checked first)

I have written fresh software only in IC3 (1.630.065.22) and saved the binary file for future use in case problem recurs. Yes, the ZIF socket on the Xgecu T48 is very handy.
 
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