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Search: Posts Made By: Retrorepair
Forum: support.Hardware 29 May 2021, 10:32
Replies: 28
Views: 2,537
Posted By Retrorepair
It could still be a cold joint somewhere, if it...

It could still be a cold joint somewhere, if it heats up and the problem presents itself. Doubtful it's caps but anythings possible.

Yeah shoot me a PM and we will sort it out. I'll post my...
Forum: support.Hardware 28 May 2021, 22:42
Replies: 28
Views: 2,537
Posted By Retrorepair
You know, I could repair it for you and in the...

You know, I could repair it for you and in the process document all the differences. Help us both out :)
Forum: support.Hardware 28 May 2021, 22:31
Replies: 28
Views: 2,537
Posted By Retrorepair
It could be a bad connection on the neck board,...

It could be a bad connection on the neck board, sounds like green is missing. I actually didn't have a picture when putting it back together this evening, wiggling the neck board connector brought...
Forum: support.Hardware 25 May 2021, 01:47
Replies: 28
Views: 2,537
Posted By Retrorepair
Well I think I've changed all I need to and yet I...

Well I think I've changed all I need to and yet I still don't seem to have auto switching. In fact, I don't have 640x480 anymore either, I'm now stuck in 800x600.

If anyone else has a M1438s and...
Forum: support.Hardware 15 February 2021, 09:59
Replies: 28
Views: 2,537
Posted By Retrorepair
That's the third version I've seen of this board!...

That's the third version I've seen of this board! It looks quite different to mine in a lot of places but it would seem the circuit is actually very similar, just a different layout.

The cap...
Forum: support.Hardware 16 January 2021, 10:13
Replies: 28
Views: 2,537
Posted By Retrorepair
That would be great as I believe mine is a...

That would be great as I believe mine is a slightly earlier model (date on the label).

I recon there's going to be a variance in the values of some of the components or maybe I've just missed...
Forum: support.Hardware 15 January 2021, 14:53
Replies: 28
Views: 2,537
Posted By Retrorepair
Sorry mate, we had a baby between my last post...

Sorry mate, we had a baby between my last post and now so my attention has been elsewhere :)

I have made the modifications which appear to be all that differs between my model and the model found...
Forum: support.Hardware 28 December 2020, 12:13
Replies: 28
Views: 2,537
Posted By Retrorepair
Actually the value of the large blue caps would...

Actually the value of the large blue caps would help, I think these relate to brightness in different modes. I can see the bigger one is 3.3uf but can't make the other big one out.

Thanks again...
Forum: support.Hardware 28 December 2020, 11:47
Replies: 28
Views: 2,537
Posted By Retrorepair
Great thanks for that, though it seems yours is...

Great thanks for that, though it seems yours is a later model so most of it is pretty different.

It does seem the sync generation circuit is mostly the same though, any chance you could take a...
Forum: support.Hardware 27 December 2020, 13:19
Replies: 28
Views: 2,537
Posted By Retrorepair
I've found some photos of a multisync chassis...

I've found some photos of a multisync chassis online which has given me some idea of what to change on my 31khz only chassis, though there could easily be more that I've missed or were not obvious...
Forum: support.Hardware 18 December 2020, 17:41
Replies: 28
Views: 2,537
Posted By Retrorepair
It could still be a driver on the neck board but...

It could still be a driver on the neck board but I'd go after dry joints on the bottom PCB where the ribbon cable connects the two or around any transformers/power resistors.

Great thanks, I look...
Forum: support.Hardware 18 December 2020, 08:09
Replies: 28
Views: 2,537
Posted By Retrorepair
I was concerned due to the file size but they...

I was concerned due to the file size but they look fine on inspection :)
Forum: support.Hardware 17 December 2020, 22:00
Replies: 28
Views: 2,537
Posted By Retrorepair
Pictures! Interestingly, even though this...

Pictures!

Interestingly, even though this model is 31khz only, the pots to adjust 15khz geometry still exist!

I have a feeling the forum has killed the resolution so I may find somewhere to...
Forum: support.Hardware 17 December 2020, 17:10
Replies: 28
Views: 2,537
Posted By Retrorepair
When you say bottom PCB do you mean the main...

When you say bottom PCB do you mean the main board? I'd say that's likely the culprit yes. Old caps could be the problem, it can't hurt to replace 25 year old caps anyway :)

It's hard to tell...
Forum: support.Hardware 16 December 2020, 10:10
Replies: 28
Views: 2,537
Posted By Retrorepair
Hi jbenam, excellent news :) I'll take some...

Hi jbenam, excellent news :)

I'll take some pictures this evening, they should indicate which components are missing on mine. I do wonder if some of the shared components will be different values...
Forum: support.Hardware 15 December 2020, 17:03
Replies: 28
Views: 2,537
Posted By Retrorepair
M1438 Pictures

Hi all,

Would anyone with one of these monitors be willing to pop it open to take some decent pictures of the chassis?

I have a 31khz only model here but am 100% certain it's a M1438 that's...
Forum: Coders. Asm / Hardware 08 May 2020, 01:53
Replies: 19
Views: 2,271
Posted By Retrorepair
I ended up working out the issue, it was the...

I ended up working out the issue, it was the logic levels that the drive didn't like. I actually ended up using an arduino with direct port control (digitalRead is way too slow) to fake a level...
Forum: Coders. Asm / Hardware 07 May 2020, 09:24
Replies: 19
Views: 2,271
Posted By Retrorepair
So I made sure the assignments to the IO were...

So I made sure the assignments to the IO were made on the rising edge of the clock and now all the signals look exactly like they do on a real Amiga (managed to score one locally).

Still no...
Forum: Coders. Asm / Hardware 06 May 2020, 13:14
Replies: 19
Views: 2,271
Posted By Retrorepair
Ok that makes sense then as minimig is set up for...

Ok that makes sense then as minimig is set up for 2 drives so there will be extra step pulses and sel1 will probably line up with them.

I just need to work out why the step pulse is so short. I'm...
Forum: Coders. Asm / Hardware 05 May 2020, 14:40
Replies: 19
Views: 2,271
Posted By Retrorepair
Ok so essentially this is going to be down to the...

Ok so essentially this is going to be down to the memory being read into the CIA.

One thing I did notice is select isn't active when the extra step/direction signals are active so maybe a real...
Forum: Coders. Asm / Hardware 05 May 2020, 13:11
Replies: 19
Views: 2,271
Posted By Retrorepair
See attached for output from my logic analyzer,...

See attached for output from my logic analyzer, the first image is a whole step, the second is zoomed into the first part of that. As you can see the signals are there, but the step isn't nearly long...
Forum: Coders. Asm / Hardware 05 May 2020, 08:23
Replies: 19
Views: 2,271
Posted By Retrorepair
Do you mean the 8520 pin mode? I see in the...

Do you mean the 8520 pin mode? I see in the hardware manual outputs can be set to pulse and toggle. I see theres a runmode bit too, one-shot/continuous. Could be it's never reading CRB or just...
Forum: Coders. Asm / Hardware 04 May 2020, 16:44
Replies: 19
Views: 2,271
Posted By Retrorepair
Thanks but that doesn't really explain what I'm...

Thanks but that doesn't really explain what I'm looking for. He mentions the signals I'm looking at but doesn't say how they are generated by the original hardware.
Forum: Coders. Asm / Hardware 04 May 2020, 15:41
Replies: 19
Views: 2,271
Posted By Retrorepair
As an afterthought, if anyone had access to a...

As an afterthought, if anyone had access to a logic analyzer and an amiga it would be fantastic to see what these signals SHOULD be doing, particularly in the kickstart bootloop.
Forum: Coders. Asm / Hardware 04 May 2020, 15:39
Replies: 19
Views: 2,271
Posted By Retrorepair
CIA/Paula Floppy Signals

Hi guys,

Long time lurker, first time poster :)

I'm not sure how familiar folks are here with MISTer but it's an FPGA based system which has a version of the Minimig core on it and also has 6...
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