As much as I can see on your photo, you did not replace IC33.
Please check its checksums with an EPROM reader such as this one https://xgecu.myshopify.com/collections/xgecu-t48-tl866ii-3g-programmer
Checksum should be the same after each read. If it is not, it means the EPROM contents is altered.
Here is what I found after 20 readings on my defective one, not a single identical result :
Please check its checksums with an EPROM reader such as this one https://xgecu.myshopify.com/collections/xgecu-t48-tl866ii-3g-programmer
Checksum should be the same after each read. If it is not, it means the EPROM contents is altered.
Here is what I found after 20 readings on my defective one, not a single identical result :
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I'm waiting for IC3, other new eproms and a programmer https://www.amazon.it/gp/product/B00K2VYBC0?ref=ppx_pt2_dt_b_prod_image
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.
well, I'll start by saying that I haven't received the programmer to check the contents of the eproms yet, but...
I received 9 new eproms: n.5 1.630.066.23 (26152) IC33 new (update 49/90), n.1 1.630.066.21 (26152) IC33 (update 28/89), n.1 1.630.065.23 (26256) IC3 (update 08/92) and finally 2 more empty 28256 to program.
I replaced (again) IC33 (Servoprocessor section), then also IC3 (Controlprocessor section) and also n.3 74HC138 (IC36 Servo - IC26 and IC27 Control).
Still not working, it turns backwards with laser pointed externally...
I have already ordered from China n.2 80C31BH1 and n.2 74HC273 .... I'm holding on💪
I received 9 new eproms: n.5 1.630.066.23 (26152) IC33 new (update 49/90), n.1 1.630.066.21 (26152) IC33 (update 28/89), n.1 1.630.065.23 (26256) IC3 (update 08/92) and finally 2 more empty 28256 to program.
I replaced (again) IC33 (Servoprocessor section), then also IC3 (Controlprocessor section) and also n.3 74HC138 (IC36 Servo - IC26 and IC27 Control).
Still not working, it turns backwards with laser pointed externally...
I have already ordered from China n.2 80C31BH1 and n.2 74HC273 .... I'm holding on💪
Is there any possibility ,that this motor was replaced/repaired earlier ,and maybe now installed with reversed polarity ? If possible ,try to swap motor + and - wires , or connector pins, and check what happens then .Also you can check motor by powering it in circuit,with cd player power off, from lab psu ,through resistor lets say 10 ohms ,set voltage to few volts ,say 3 volts ,and just check direction .Maybe stupid idea ,but ... i'm assuming this backward rotation happens not instantly after power on ,but after trying to focus to cd .
The problem is on the mainboard
Attachments
These are very unlikely faulty. My bet is on the program chip (IC3).
Thmartin, thank you for your help and I am also convinced that it must be a problem in the Servoprocessor and Controlprocessor circuits or in other adjacent parts located on the S-Bus, C-Bus and P-Bus lines. At this point I do not believe it is the eprom IC33 as in your case, it is very unlikely that all the original eproms I purchased are corrupted, but rather something very similar that produces the same effect. In any case as soon as the programmer arrives I will do the eprom reading tests.
Hi Thmartin
So... with my programmer I tried to read the bin files, but honestly I don't know what I have to look at.... I don't understand your table where you report the errors. Anyway after reading them I did a check with a button in the programmer software, the old IC33 27128 that was mounted reports "verification with error", while trying another IC33 of the ones I bought, it results "verified success". I also tried the old IC3 27256 and it resulted "verified success". Now IC3 and IC33 are mounted "verified success", the problem remains... I'm bringing my concentration on pll-system clock section...
So... with my programmer I tried to read the bin files, but honestly I don't know what I have to look at.... I don't understand your table where you report the errors. Anyway after reading them I did a check with a button in the programmer software, the old IC33 27128 that was mounted reports "verification with error", while trying another IC33 of the ones I bought, it results "verified success". I also tried the old IC3 27256 and it resulted "verified success". Now IC3 and IC33 are mounted "verified success", the problem remains... I'm bringing my concentration on pll-system clock section...
Just to be sure IC3 is OK, do several readings in sequence with your EPROM reader and make sure the checksum stays the same value each time. This "Verified success" message doesn't garantee the contents of the EPROM is valid, it only tells that the reader was able to extract the contents successfully.
what do you mean by checksum? If we mean what is written after each read, then from what I can see in all those lines (there are many more scrolling through the bin file) it would seem that each time the result, at least for this eprom, is always the same...
The concept of an EPROM checksum involves verifying the integrity of data stored in an EPROM by computing a small value derived from the data. This checksum is used to detect errors in the data, such as those caused by corruption or incorrect programming. It can be calculated using various methods, one common approach is to add all the bytes of the data together and accumulate the sum in a 16-bit word, discarding any overflow beyond the 16th bit.
Another method involves using a cyclic redundancy check (CRC), which is a more sophisticated error-detection technique. CRC involves computing a checksum of the data and storing it, then recomputing the checksum on the same data and comparing it with the stored value to detect errors.
In all cases : the software for your EPROM reader has a box (and an option) to display the checksum. The value displayed in this box SHALL NOT CHANGE from one reading to another. If it does, this means the data is corrupted.
I hope it helps.
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