Posted By
javierglez
on 2021-09-22
13:56:43
|  Help troubleshooting
I was checking a disk drive that won't initialize and I've blown something in a C16 of mine. I'd usually try to swap socketed chips but in this case I'm cautious to do so before checking for shorts etc.
If someone has an idea what could be going wrong here I'd appreciate some advice.
(for a few moments the computer kept resetting and displaying the startup messages, now it just shows this trash)
(PS I uploaded the picture twice to the website, sorry)
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Posted By
javierglez
on 2021-09-23
05:35:14
| Re: Help troubleshooting
The motherboard seems to be OK, and so is the TED. So I guess I killed a 7501. It's sad because I could have tinkered with a C64 instead, to check the disk drive.
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Posted By
MIK
on 2021-09-23
13:00:12
 | Re: Help troubleshooting
Crazy looking screen the likes I've never seen before. If it turns out to be the CPU put a heatsink on the next one.
Bil Herd and one of the designers of the TED machines said such chips as the TED and CPU should of died long ago and is a merical some still work, the fact they do work is because over the years people have been swapping chips to keep the machines alive.
But yeah, what Bil said is some what true and I'm guilty of swapping the odd chip. I recall he did say heat is the main cause as to why they don't last forever so a heatsink can help. If one does die it's just one of those things, can't be helped.
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Posted By
javierglez
on 2021-09-23
14:44:10
| Re: Help troubleshooting
I saw a thread showing up a similar screen, but it was an unresolved issue.
I took the working part from a machine with a minor issue which I want to repair too. But you are right, I should put a heatsink.
Anyway I think it was my fault, I wanted to see why the 1541C head wasn't moving, I detached the drive board, put a paper under it to avoid a short, I felt it was too thin but didn't want to spend more than 5 minutes on it.
The drive is grounded, the C16 isn't, who knows, I don't know electronics and I rarely tinker. Maybe a VIC20 or a C64 would have standed, after all, the 264 are known to be delicate.
Maybe I should buy the CPLD replacement to take to the meetups and keep the real thing at home. We have the first meetup after the CV.
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Posted By
MMS
on 2021-09-24
01:39:02
 | Re: Help troubleshooting
If you check out the content, it is evident, that those characters are not valid ones.
So I see three options:
1) really the content decoding is wrong, and the CPU has troubles.
I think this is the most expensive exchange, so maybe it should be the last step to swap the CPU.
2) the ROM is damaged, and it contains now random values, including charset, or the startup code
Maybe it is worth to try to swap the ROM (s) (MCes has some modern, low power replacements) as from a damaged ROM inside the machine it cannot run it's own microcode.
3) as not only the charset is damaged, but instead of the initial startup places (on the top os the screen) the full screen has random values, some of the lower RAMs could be dead (too), where the screen and color memory exist, even the zero page with so many important system values.
RAMs typically soldered inside, so I would not replace them, but there is an option to get some 41464 chips and try to piggyback the suspected one temporarily. (sorry, maybe the type is not correct, it could be for the 64K version, but I do not know by heart the 16K RAM chips)
https://www.youtube.com/watch?v=mxhEgmG6vh4
If it cures the issue, then you found the defective RAM chip.
There are several options to change the internal RAM chips, and may do the 64K upgrade at the same time. including the Lotharek CPU swap contains 256KB SRAM next to the new CPU, MCes has a 64KB upgrade put the extra RAM under the TED IC, very elegant method
This one is also nice:
https://www.youtube.com/watch?v=5dnHICcseGI
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Posted By
javierglez
on 2021-09-24
08:45:25
| Re: Help troubleshooting
Thanks MMS, the old CPU now produces a black screen, I guess I witnessed its final moments. I swapped the CPU and now it boots correctly and can read a disk directory. I only have C64 disks at hand, so I can't run them. But it reports the usual 60k something bytes free, for the moment I'm assuming the rest of the board wasn't damaged.
But yes, I can't understant how a bad CPU can produce such weird visual effects that would point more to RAM/ROM&TED.
I feel relatively fortunate because tomorrow I attend a meetup, and this is my only 64k C16 (I have an unexpanded one too - I haven't decided which one I will set up). I have a couple Plus/4 readily available but they weren't sold over here, although if the meetup was CBM specific this wouldn't matter.
I already ordered a replacement from Hungary. I'm considering getting one of these new substitutes too, the 256k looks interesting, but apparently there's no software for it yet.
The CPU for the faulty C16 comes from another Plus 4 I own which has what looks to me some minor memory issue. I've been wanting to try the RAM piggyback technique for some time actually.
I own a C16 board without TED/CPU and major memory issues - the startup screen appears almost empty. I had no intention to fix this one but I may change my mind now.
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Posted By
retroscener
on 2021-10-09
17:40:57
 | Re: Help troubleshooting
Well somehow I've now managed to break both my C16's. Neither now powers on. No power at all. No red light, totally dead. All I did was swap one red power led light over with another to one system as had to fix another problem which I did. Y'know, sacrifice one C16 to repair another, but it was really just broken screwholes in the keyboard casing as well as a dodgy joystick port (neither which has been the cause of the issue
), but it meant having to swap around a couple of chips too which also should still be working fine. Now this.
Problem is both the red power lights although same pins have slightly different plastic casings. It did cause an issue of temporarily not powering on unless I jiggle with it a bit on one of them. But pretty sure I never had that problem with the other, yet suddenly that is failing to power on too.
Well either both the PSU's have blown or something inside the C16's have. I am really unsure. I am quite certain that it's not the two chips as they were still working when one C16 died, just before my other one did. Confused? So am I.
I never have problems with my C64, just my C16's. I may just give up on the real thing altogether now and get my Turbo Chameleon C16/Plus4 core up and running with a C16 keyboard.
Or I could send one C16 off for repair, but I don't want to risk damaging it again with a faulty PSU if that's the issue.
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Posted By
MIK
on 2021-10-09
20:45:31
| Re: Help troubleshooting
I've never known any chips to die in a C64 or C16/Plus4 when the machine is warm so powering on and off won't harm them while they are still warm. The only time you might get a surprise is when the machine is stone cold, or the PSU fails but I've never lost a Plus/4 one. Lost a C16 PSU though which dropped in voltage causing the machine to hang if I pressed play on tape...
If the issue happened before and you know the chips are fine then there is a chance it might be the PSU. If you have an adapter from something else around remember it's 9 volts DC for a C16.
Double check you have connected the keyboard back properly, just in case...
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Posted By
MMS
on 2021-10-09
18:47:31
| Re: Help troubleshooting
Well, actually the C16 PSU is underpowered, it died two times I had the original C16 HW with 64K RAM, the Graetz diodes is pretty below expectation (my father repaired them, I was too young to touch a safety component at that time, and still did not learn to solder properly :-) ).
Worth to try an aftermarket 9V PSU first, I have a multivoltage one with 1.5A limit, and it works prefectly with my C16.
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Posted By
MIK
on 2021-10-09
21:13:17
| Re: Help troubleshooting
Sleep on it, it might help.
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Posted By
unclouded
on 2021-10-10
00:51:02
| Re: Help troubleshooting
What does it mean that the pattern seems to change every 16 characters? And that the colour changes across the display as well?
Since you have another C16 that is mostly working, instead of trying known good chips in a broken machine (which might have multiple failures), you could try suspected bad chips in a known good C16 and see if they cause it to stop working, at least for the socketed chips.
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Posted By
MIK
on 2021-10-10
05:12:09
| Re: Help troubleshooting
Seeing as Argos take stuff back.., and if you can't wait there is this:
https://www.argos.co.uk/product/9829701?clickSR=slp:term:multi%20voltage%20adapter:1:2:1
Only pain is knowing which way the tip should go but,... there should be instructions to say which way AC/DC is with the +/- marks on the cable and end-connectors but if not,... if you have a small Radio, CD player, Internet Router or something else that takes an adapter look at that for the AC/DC & voltage and test it before trying the C16 as the way the +/- meet each other will say if it's AC or DC to that device.
If you like it and wanted to keep it you could "black tape" the connector to stop the cable coming out.
Taking it back.., just say you wanted USB and thought it had it being a multi purpose adapter. 
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Posted By
retroscener
on 2021-10-13
22:59:46
| Re: Help troubleshooting
Thanks MIK. Unfortunately they don't deliver this adapter to my postcode and would need to pop into town to collect it. But I'm still recovering from the surgery plus the atrophy resulting from my long stay in hospital which all makes it difficult to walk. Will take many months for 100% recovery. I guess I can wait a few days for the adapter and PSU on eBay. Meanwhile I'm now figuring out a new installation problem on my Turbo Chameleon 64 with its new C16/Plus4 core. Seems to be a minor monitor display issue. I may need to rely on this for a while.
Update: The new PSU arrived. It did come with a UK plug after all. Both machines still not working though so need to send one in for repair, just my luck. Meanwhile I have the Turbo Chameleon which has an FPGA solution for my C16/Plus4 fix, just attached a real C16 keyboard to it and awaiting the keyboard fix plus D64 update. All the more important keys wok anyway. Right now the home key is not configured. It'll do for now.
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Posted By
MIK
on 2021-10-14
04:31:13
| Re: Help troubleshooting
Any way Chris can help from old commodore16.com? You were local to him?
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Posted By
retroscener
on 2021-10-14
04:39:33
| Re: Help troubleshooting
Yes fairly local. A few stops on the train. He helped with a 64k upgrade before I think. Not sure if he is able to repair this though.
I also need someone's help who lives in an EU country to accept a delivery. I need to order a cable for my disk drive so I can plug it into my Turbo Chameleon, but they cannot accept orders under £135 due to VAT Brexit laws. I can pay them for the postage to me in the UK. This is just one reason why I voted to remain.
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Posted By
MIK
on 2021-10-14
09:55:14
| Re: Help troubleshooting
Might be an idea to ask in a brand new topic as a request hiding in an older topic might not be seen by all.
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Posted By
javierglez
on 2021-10-14
12:30:11
| Re: Help troubleshooting
Is there a reason to use a real 1541 with the Chamaleon instead of disk images?
I mean, I burned some disks some time ago, some demos (btw I don't know where I put them), as well as Pet's Rescue and Alpharay, when they came out, but mainly I use SD2IEC.
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Posted By
retroscener
on 2021-10-14
13:07:58
| Re: Help troubleshooting
I own the collectors disk edition of both Pets Rescue & Alpharay. Not cheap. Also normal disk edition of Adventures in Time. I wouldn't like to part with them as they are there to be used. This cable I need to buy also supports printers. Overall it will make for a far better alternative as it progresses as the 264 series are becoming rarer, so adding real hardware support is so important for the scene.
D64 images are currently unsupported with this FPGA core but have been reassured it's coming very soon, he is already working on it.
P.S. Apologies for hijacking your thread. The topic title seemed fitting, plus it bumps it up for you too.
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Posted By
retroscener
on 2021-10-14
16:27:37
| Re: Help troubleshooting
oops. I've changed my password but now I cannot login. I must have used illegal characters. Help!, lol 
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Posted By
MIK
on 2021-10-14
16:49:58
| Re: Help troubleshooting
Send an email to Csabo and ask him to change it, he'll change it and let you know. Once logged back In change it to something more normal. ;)
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Posted By
retroscener
on 2021-10-14
17:20:32
| Re: Help troubleshooting
Done. Email sent. I seem to recall this happened to me before a couple of years back, and I was told not to use special characters. It's easy to forget these things as it's not mentioned on site. I guess he will email me a temp password and I will change it when I log in back to a more standard one for all the code breakers out there to suss. Doh is me
Edit: Fixed, thanks. Seems special characters are allowed after all. Unsure what happened there.
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