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Old 04 July 2017, 12:08   #45
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Join Date: Jun 2017
Location: Madrid / Spain
Posts: 15
The 5h pot and Multimeter pins?

Originally Posted by Akira View Post
Now, for some people, after they did the original/CDR test above, the unit wouldn't read shit or read partially. This means that you have to do some tweaking to the potentiometers that calibrate the CD unit. There are five potentiometers in total and varied ways people swear by about how to go at them. A word of warning, these pots are VERY, VERY sensitive, so you have to do MINOR adjustments to them and remember how they were originally. For this my recommended way to do it is to measure the value they are set at with a multimeter, by putting a probe in the middle pin and another one on one of the sides (always the same side!). The pins are easily reachable on the bottom of the controller board PCB (where four pots are found) and on the back side of the lens' PCB.

I didn't have to do this tweaking but just in case I measured them all. I had to measure the controller PCB ones in the 20k Ohm range and the lens one in the 2k Ohm range.

I won't delve into this method because I didn't do it but more assistance is found at Stedy's page:
He doesn't go into touching the lens' potentiometer at all, though. FOL had recommended to ONLY touch the lens potentiometer and leave the controller board ones alone. If I was you and had this issue, I would start moving the lens pot before I try dealing with 4 pots at the same time. Good luck though, and although some people recommend taking a pic or marking with marker where the pots originally were, take my advice and measure it all with a multimeter and write it all done, it won't get more precise than that.

I hope this helps people revive their CD32s, if you have any further questions don't hesitate to ask in this thread! I'll respond to the best of my abilities.

Thanks for such a great post.

In my case I don't need to replace the lens but just [hopefully] adjust the potentiometers. I hope that you can help me with questions related to your explanation:

- Where is the 5th pot? I was only able to find the 4 FEG, TEG, FEB & TEB pots.

- Could you explain further (or illustrate with a pic if possible) where exactly are the pins to use with the multimeter?

My story is the following:

After having an Amiga 500 during my youth and loving it very much, I had to give it away and move to a PC that was better suited for my university studies just when the CD32 came out at 1993. I would have given an arm to get a CD32 at that time.

Anyway, I had the chance to get a CD32 a few weeks/months ago to try to revive the good old times. I got it without power supply and I had to use a 3rd party PSU for starters (Taifu AC Adapter (5V 2A, 12V 2A) ). Then, I tried CD-R copies and nothing worked so I started to panic until I read in EAB that there were ways to tune the CD reading.

With my very limited electronics skills I tried to follow:

I only managed to go from CD-Audio glitchy playback to very smooth playback moving well between tracks, etc. but playing CD32 CD-R games had exactly the same result:
- A very few games take minutes to get to the first screen and then nothing.
- 99% of games just show a black screen.
- The CDs seem to spin well (doing some noise), I see no issue there.

I burned the CD-Rs at minimum speed that my drive supports: 4X

Sorry for the long post, I considered creating a new one but I didn't know what was more appropriate.


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