CD32 with or without plugged joypad/stick going up constantly

[Cobe]

Any ideas?

I have this cd32 for years. We had great times and we still do. But I must confess that in these few years I have connected mega-drive joypad few times and once I hotplugged cd32 joypad. Though it's been a while and nothing happened till now. Also recently my joypad's cable was starting to lose contact so I suspect that it could be the thing that caused this.
It seems that problem is not that persistence and that sometimes it goes away if cd32 is running longer. Though it can also happen that there is no problem on power up but than later it appears.

I could add that year or two ago I replaced those two big main suspect capacitors.

Could it be "just" another capacitor needing time to warm up and refill? Or, I
hesitate to say, its maybe something more sinister, like, akiko going bad...

Re-reading... I should clarify that it acts the same with any regular commodore one button joystick plugged in as with no joystick connected at all.

[Amiga1992]

I had this problem in my A500 and it was a multiplexer lying after the joystick port that was faulty. I know nothing about the CD32, but I guess the ports work in about the same manner? Meaning you would have to change it, if you are up to the challenge (must be some surface mount shit).

For the time being I guess you can poke around with a multiplexer following the schematics of the CD32 mainboard http://www.amigawiki.de/doku.php?id=...ice:schematics

A quick look says that U34 is possibly your culprit.
Here's a spec sheet of that multiplexer:
http://www.futurlec.com/74LS/74LS166.shtml

[Cobe]

Thanks for giving me the next main suspect. I'll investigate when I get time. Though my soldering "skills" are probably poor match for it but I'll have to try eventually.

[Amiga1992]

The resistor pack connected to it might also be the problem. You have to measure it all and see where the problem is. Start with the mux.

I didn't get the problem more or less, it was persistent.

I don't think capacitors can create this issue, but CD32s need full electrolytic capacitor replacements anyway, so you might have to do that anyway. The big ones don't count, it's the tiny ones that are assholes.



Good luck

[Cobe]

Thanks, I'll need it

[xArtx]

For the suspect joystick port, connect pin 1 to pin 7,
and if that stops it going up, a resistor pack was bad.

[Cobe]

Thanks for the tip.

In last two hours or so I'm mostly sitting in a room with cd32 turned on, no joystick plugged in. On power up there was no problem. In first half an hour no problem. Than in next hour problem appeared shortly few times. I wasn't quick enough to connect pins before problem went away by itself except one time when I'm pretty sure it stopped right at the moment I connected pins. But it didn't reappear the moment I disconnected pins... In past hour problem didn't appear again and I'm waiting for it just to be sure that it wasn't coincidence that it stopped at the same moment.

If its resistor would you know which one would have to be replaced? Those are that surface mount resistors beside the port I guess? Damn they are tiny... With no prior experience would I be able to replace it?

[Amiga1992]

I wouldn't do surface mount components without experience. You need practice.

[Cobe]

Yeah, you're right. I could find someone to do it for me just need to know which one.

btw, another half an hour passed and now I'm playing it and no problem reappeared.

[xArtx]

They are usually resistor packs, but in a CD32 maybe individual SMD resistors.
Ideally a rework blower to get them off, but if practiced, with soldering iron.

Ok, while touching the RF shield (perhaps at the edge of joy port 2) to prevent static damage,
stick wire just into joyport 1 pin 1, insert audio CD and load CD player.
When it goes up on it’s own, if touching the other end of the wire makes it go down, resistor pack is bad.
Touch RF shield before touching wire also.

[Cobe]

Friend and I played with Amigas yesterday and I can confirm that connecting pin 1 and pin 7 stops it going up. Going up doesn't start again right after I remove wire but after some shorter or sometimes longer period.

Is this enough to confirm that resistor pack is bad?

Are these the one that need to be replaced?

All of them or one? What are their exact number and value which should I know when searching to buy them? Are they fairly cheap and common? If they are I'll replace them all. I mean I'll give it to someone who knows.

[Amiga1992]

Originally Posted by Cobe

Is this enough to confirm that resistor pack is bad?

I don't know, I would test them with a multimeter, and also the multiplexer.
Just to be thorough.
But as I said, without experience with smd and those tiny components, why bother? You could end up doing irreparable damage.

By the way that's not R370 as the schematics say. Can't even find them, it's such a compact motherboard, everything is next to each other.
I can't even find E365 to E368.

[edit] I knew it, the rest are on the underside:

The top side only has bank F

[xArtx]

8 resistors all called R370 yes.
They are all 4.7k, and resistors are common.

[Cobe]

Thanks guys. I'm not touching them myself. I'll find someone with experience but hardly he'll have experience with Amigas so I want to know as much as I can to point him out what to check and replace.

[solidcore]

Cobe wise decision my friend - I never touched smd before last month but since I've now soldered a tf328 I feel more confident on smd repairs such as the one you're facing . I think the hard part about those little bitters is they're tricky to place tacking a single pad only is the key and moving them into it while you heat the pad up . As for removal I believe putting solder bridge across it helps as you can Heat both sides together - hot tweezers would be nice I should get some lol, although you can heat both sides up fairly quickly and pull them out but you'll need to be quick .

Most of all just have fun whichever path you take hehe

[Cobe]

haha will do