Atari 520STFM No Video Repair
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- Опубликовано: 11 сен 2024
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Looking at a faulty Atari 520STFM. This system was kindly donated by Marauder666 (Andy) over on AtariAge.
#atari #atarist #repair #retrogaming
Blimey, that was extremely difficult to fix. Your dedication to finding the problem is brilliant!
Plugging a mouse and joystick in was notoriously pain in the backside. 😂
This is why everybody bought short extension cables.
I had a Mega 1 STF and it was even worst!
Use acetone to glue ABS posts and cracks. A few drops and wait half an hour for it to evaporate and it's almost like new because it's welded together. A cotton bud can be used to wipe acetone around the joint or along cracks on the inside of the case as well for extra strength.
Great work Chris as usual. Funnily enough i have reflowed two of those joystick ports myself just recently. Almost every solder point on port one had a crack around it.
Thanks to Marauder666 (Andy) for donating this to the channel!
At one point there I was feeling the temp of the WD1772 (FDD controller) and referring to it as the AY chip. The sound IC is to the right of the 1772 there (looking at it from the front). I think that's the only chip I forgot to point out! Some articles (wikis etc) refer to the GLUE as GLU - but in the Atari service manuals its called GLUE.
The replacement PSU is here:- www.exxoshost.co.uk/atari/store2/ Currently out of stock, but hopefully in a few months they may be available. You could use a meanwell, but tbh I've seen a few experienced people pointing out that meanwell PSUs aren't that great.
Hi Gadget, well on the ST series, the caps have to be serviced anyway. Atari used shit 3rd grade caps on most of their computers. Only few series got very good caps (i have one of them).
Seems that the exxos-PSUs are back in stock now (08.08.20), 32 of them!
Jan Beta shows an quite good alternative PSU for the Atari STF (and Mega ST), which seems to work well and also adresses some video-issues (noise and stripes in picture): ruclips.net/video/7F0Y4kwT5es/видео.html
It's a very common PSU which can easily be found anywhere, like ebay, reichelt.de, Amazon etc.
edit: saw that you're already pointing out these Meanwell PSUs.
Thanks =D Yes, not keen on those meanwell PSUs tbh! I've heard a few horror stories about them.
@@GadgetUK164 hi gadget, could say what kind of horrors?
@@dlfrsilver Design fault that made large batches of them fail (safety recalls). Also heard a few people pointing out that the caps used are not very high quality or fake brands etc. Now that could be because there are also fake meanwells out there. Unless you buy from a dealer you are most likely buying a replica.
Ugh, I remember those bloody RAM expansions, we bought 150 or so catalogue return Atari STs of various types, 1040STFM, 520ST, STFM etc, the majority were PSU faults, on the PSU you need to check the small value caps on the primary and also the high value resistors, they go much higher in value or even open, causes intermittent or no start.
Make sure you replace with a suitable high voltage part.
next up were floppy faults but we had a few with bodged RAM upgrades and those bloody boards were a common problem, bent pins, destroyed PLCC sockets, bent or broken pins on the PLCC chip and shorts where they'd been fitted by ham fisted 'experts'.
There's still a maxed out ST of some description in my loft, the type with 30 pin SIMM sockets under a removable shield in the middle IIRC.
Too damn hot to find it and get it down :)
That's awesome you got it working Chris, I'd have never found the dodgy via.
The bits were epoxied, but it was quite old, and probably had a bad mix.
Thanks ever so much for donating it to me =D Very much appreciated!
me: Saturday morning in my PJs...not in the mood for anything technical....oh wait...a new gadget video...Shove on the coffee machine, it's gonna be a good start to the day :)
I filmed this before I sent you did the swap with you on the ST, or I would have mentioned where it went =D Thanks for the Elk - haven't had chance to look at it yet!
@@GadgetUK164no worries Mr.G. I'm planning on a quick video look at the ST you sent me so will mention it and link your channel :)
Great repair video GadgetUK164. Keep up the good work.
Good sherlocking on that fault! I'd be tempted to try repairing the broken parts on top with some acetone, but that can be risky too.
1:25 I have made a printable plug for that connector, it is available on Thingiverse.
1:33 It has composite video only in STfm and STe, units without TV modulator doesn't have composite vide, only composite sync.
2:05 it is apparently a late batch unit, and this is a place for Extended Joystick ports in STe case.
10:13 You can fit an STe blitter and it will work fine, I have one in my STfm, but the sockets are impossible to buy, I've modified a standard socket (bend it's pins) to fit into this board.
Thanks for some of the info there! Will check out that connector on Thingiverse! The STFM does output RGB, as does the STe! The Blitter from the STe doesn't fit the STFM - it's a Blitter from the Mega ST, that's where most of them come from. I have a Blitter in my STFM here too! The Blitter chip in the STe is QFP (not PLCC) and has other stuff merged in with it I believe. I have a spare STe Blitter chip here and it's nothing like the one needed on the STFM. Those sockets are much harder to find now, but I have one or two spares if I ever upgrade an STFM again.
See here - the STe Blitter is combined with MMU and Glue. www.ebay.co.uk/itm/NEW-Atari-520-1040-STE-Mega-STE-SMT-MCU-Glue-Blitter-144-Pin-IC-C302183-002/152129239593?hash=item236b9bfa29:g:p1cAAOSwGIRXYENJ
@@GadgetUK164 I said that the Composite Video is missing on units without a TV-out, not the RGB. STe Blitter is the same as Mega ST. Only very late STes (1991) had Blitter integrated with GST-MCU (Glue+MMU), which is QFP chip. Original STe desing (1989) was using the same Blitter chip that was used in the (late) Mega ST units.
@@TzOk Thanks! I've not seen one of those early STe boards! Makes me wonder where those Blitters are coming from on eBay - are people destroying old STe's to obtain them. That said, they may have come from Best Electronics in the US - I know they have a tonne of ICs as they bought all of Atari's stock when then they went under.
@@GadgetUK164 I'm afraid they come mostly from a complete STes scrapped for parts. Best call $40 for a Blitter chip, that's a crazy price. Few years ago you could buy a complete Mega-ST for that.
Watched the whole video and subbed. Great video. I'm really fond of those old Atari ST machines. Lovely! Happy new year!
Thanks for the sub! Happy New Year =D
Cool that you got this machine back working again! Looks like it was a tough one! (Reset issue etc.)
Never saw an STF with such RAM-chips btw. And I thought I've seen them all. 😮
6:02 that fourth metal spacer is for grounding the floppy-drive.
Thanks =D Yes, I realised that spacer is to ground the FDD, but there are other ways to do that. For one thing, the ground from the drives power (and the IDC) likely connects to all the metal work on the drive anyway.
Wow! This brings back some memories. Thanks!
Nice repair!
I've got one of those Epson drives in my ST, and for the life of me I couldn't get that stupid metal shell off of it to clean it (which it needed). Even with the screws removed, it was hopelessly stuck on there; I ended up having to cut the damn thing off. The dri've's now naked, but at least it works!
Great vlog, loved my STFM and later the STe, nice to see these machines are being kept going, keep it up matey
Many thanks!
I have an 520 STfm - paid £5 and a 1040 STe, paid £3 for it and it came with the mouse, manual and a couple of games.
Nice!! I paid similary crazy prices for my STFM and STe. The STFM was £15, the STe was £18.
@@GadgetUK164 I got most of my ST's for free. The only one I did pay for was an STFM that came with a colour monitor, the mouse, joysticks and tons of games for £20 - from eBay! :D
I had a super early 520STm.... 1st revision TOS on disk. Then TOS on ROM - required the 4" dead drop to reseat the chips. Then TOS on ROM with retaining clips. The double sided drives were not even available until a little later - so only the single sided...
Only the 260ST had 256K RAM, but not many were made (because they quickly realized that wasn't enough RAM) and mostly sold in Germany, France and (maybe) UK, I think. They (and maybe some very early 520STs) also originally booted TOS from floppy because the ROMs weren't ready yet, leaving only 64K RAM available on the 260ST. Also, I think only the external SF354 drive was singe-sided, with all STf (and Mega, etc.) machines having built-in double-sided ones. If I recall at the time, the SF314 (double-sided) was almost US$100 more than the SF354, so a lot of pre-STf 520ST owners had the single-sided.
nice repair, don't know how you do it, truely skillfull. Still my heart belongs to the Amiga.
Thank you very much! That's very kind of you =D I too love the Amiga more I think! I have tonnes of nostalgia for the ST though.
Subscribed! Love your channel and look forward to further instalments. :)
Thanks =D
Looking forward to watching this while scoffing my sunday roast!
=D I am hungry now lol
Thank you Sir, your are inspirational! Greatly appreciated.
Thanks =D Very much appreciated =D
Hi! Those data bus signals look like what Adrian (Adrain’s Digital Basement) found in a board he was working on (TI 99/4A) but it had an MC6810, rather than the MC6850’s you have. IIRC, one of them, and a ROM were bad, and were doing weird sh*t on the data bus.
What was happening here is one half of the board wasn't reset properly. The net result is things were writting to the databus when they shouldn't be. That's why the 6850's were getting hot - most likely databus connections clashing with the CPU and anything else that might have been not reset properly.
Amazing keyboard to fit my laptop inside!!!!!!!!!!!
Interesting video, thanks for posting.
Frontier Software -> Marpet Electronics. Those were the days.
I worked at Frontier for a while. Upgraded over 500 Atari machines with the XtraRam module.
Hand soldered lots and lots of those DIMM modules they made. It was a mad time with quite a few through-the-night sessions and almost every Saturday; just to keep up with the work load.
I miss the computer shows that were held in Manchester, were I got to see the Transputer Atari (that really blew my mind away) and a German couple demonstrating their voice control software that didn't need training ! There were also plenty of Amiga things to do too.
It really was a wonderful time to be alive.
=D The best times in computing I think! I love modern computers too, but there was just something so special about the 80s and 90s and computing.
the side bit is for joysticks and mice!! thanks......
Merci ;)
Yeah hot air is my new favorite way to deal with plated through holes as well.
It's just so much easier and very hard to damage anything!
Thank you for this video :)
why the switch from isoprop to vinegar recently? Which do you recommend for what tasks?
IPA won't do much to corrosion - other than clean contamination off the top of the corrosion. Vinegar will eat at the corrosion making it easier to remove / clean up. I then clean with IPA.
you mentioned it was a mould cutout?? that one
What would stop a 520 stfm from booting when the floppy drive is connected, I removed it and it would then boot to gem. A gotek also works just fine.
I would first suspect the floppy drive tbh!! Especially if the gotek is working! Measure the 12v supply coming from the PSU too, but I don't think a missing or low 12v would result in it not booting up at all. If the FDD is OK, it's possibly a fault on the WDC1772.
@@GadgetUK164 The 12v was good, I tested the PSU first. Are these standard pc type floppy drives ?
The EEVblog ruler brings back bad memories. I'm sure that's how Dave Jones doxed me.
LOL! Did you not get yours or something?
@@GadgetUK164 I got it, then he used the address I gave him to publish my name and address online when I suggested that "one hung low" is a bit racist.
@@kuro68000 That's really disapointing - I didn't expect that of Dave!
@@GadgetUK164 obviously I didn't either, but in hindsight all the signs were there...
Ya, I lost my Atari 1040-e in 2007. Too bad it's a relic. Anyone know where to buy one (cheap?)
I've repledged on patreon BTW (only a small amount but I hope it helps a little, once I get a job I'll up it)
Thanks Marky, very much appreciated =D Hope you get something soon - or continue to build your repair business =D
@@GadgetUK164 yeh me too. probably a combo of the two if im lucky :-p
GadgetUK64 can can advise me pls. On start up of my 520STFM I get a white screen which is just half white at the top and black at the bottom but fading white to black almost like picture is moving. Then after a few secs, I get the green screen as normal. However put a disk in and try to click on drive A icon then the computer freezes. Also if I put a disk and turn on the machine there is no real effect and the white and black screen persists with no green screen desktop. I checked the monitor socket and reflowed the solder. I am wondering now what ICs are causing such issues? The ROM TOS ICs? disk drive is fine as it works on my 1040ste. Any pointers would be helpful...
My first thought would be RAM tbh! Unless the freeze is occuring just on disk drive access. Before doing anything on an ST, recap the PSU! A power problem would cause the issues.
Hi I have a mega set, turned it on, it’s lost 8 colours and rasters no longer display? Is that a shifter chip issue
Honestly, no idea! It's perhaps worth ruling out the shifter by swapping it - they are normally socketed.
Much swearing later.
I know that feeling with my PC.
=D
I noticed you saying Atari and the a500 share alot of chips ,what would it take to run a a500 game on the Atari or atari game on a500? Challenge
There aren't that many chips the same between the ST and Amiga - there's the 68K CPU (that made porting games between the Amiga and ST easier), and there are chips that do similar types of things - but work differently etc. Most of the complexity of porting between Amiga and ST relates to the graphics and sound hardware differences between the systems, the ROM (OS), and the memory map. Most of those things are very different between them.
I *really* am unsure about those caps. For one, I see absolutely zero reason in the world to re-install 30+ year old electrolytics once they where removed in the first place. And more important, ESR and measured capacity aren't near enough to tell if a cap is good or bad - it might leak electrically like mad and those ESR+capacitance meters are 100% *not* able to tell. In fact, as capacitance measurement is usually done by measuring time to charge, its a well known fact that electrically leaking caps tend to overachive on the capacitance measurements as it takes longer to charge them, fooling the meter. Also does one really think 33 to 34 year old (520STFM: 1986-1987) caps are in any form better than brand new panasonics? And that by some coincidence, the +-20% lottery is always on the plus side on these old caps, and well beyond? (125% for the 4700 one)
Sure, don't believe me, as I am just the random guy on the net, but believe acknowledged experts like Mr Carlson from Mr Carlsons Labs ruclips.net/video/LhovRIM5xAo/видео.html
He shows it over and over and over and over again again in his videos that just measuring ESR and Capacitance is just as good as just reading tea leaves to determine if the cap is good or not. There is a reason why leakage testers like the Heath IT-28 where are around even in the sixties.
PS: over 130 % on the 2200 one... while the new 100s "only" reached mid 90ties, as for them the +-20% lottery "funnily" also goes to the low side. These old caps where fishy. (pun intended).
PPS: also ESR usually reads lower when caps tend to more and moire short out internally. So these overachiving "super low esr" ones could also just be just super leaky.
I totally agree! I just didn't have a full set of caps for this - and that isn't what I do. That is, I don't do recap every single thing I show on my channel, because a) It's boring to watch b) Costly if I replace every single cap and c) Takes more of my time up, and finally d) People get bored watching me recap everything. The over capacity is NOT a sign of a problem, these caps measured higher capacitance like that back when these were new! I know that because the other cap meter I normally use shows the same sorts of "way above tolerance" that they did when I used that meter on them back in the day. The ESR is fine too, better than most of the new caps I had to hand. But I agree, replace them while you are there! Retro Marky owns this one now, and can recap the PSU if he chooses.
In general the caps on ST PSUs do often need replacing! But they aren't leaky - my meter does indicate leaky caps too!
@@GadgetUK164 Hate to be "that" guy, but according to the manufacturer, it doesn't. ESR and capacitance only. If it could, Mr Carlson also would not have to be the first to build a low voltage leakage tester, too.
Sorry this topic is just my pet peeve. Speaking of pets, my 8032-SK lives again, couldn't be happier for the moment :)
I just put a set of tos 1.04 in my old 520. It was working fine so I put the case back on and now nothing. Power light is on, but the drive doesn't seem to accessing (external gotek), no video. Any ideas? It's sentimental to me, I did my college project on it and it set me up in my career so I'm feeling a bit gutted right now. Cheers!
Update: floppy is reading sound is playing, keyboard clicks. Output through scart I get a shaky signal but I can see the picture. 1224 or VGA which previously worked show nothing. Had an old board from a mega ST. Tried the shifter from that, same thing. Any ideas what could cause this? It's almost like I don't have a valid sync.. thanks!
Hard to tell, maybe something was not connected very well after taking it to pieces and re-assembling it? Has the PSU been recapped?
@@GadgetUK164 no it hasn't been recapped, could that cause something like this? I'm getting another ST in the mail soon so maybe I can try and probe some things and see what's different.
Some progress. I had an old Mega ST board that had the chips in it still. I replaced the GLUE and I got a solid video sync, white screen. Something my original wasn't doing. Unfortunately with this GLUE the floppy didn't try to read or go any further than the white screen. Do you think it may be a GLUE issue? I've ordered one more online that I can try when it arrives.
Replaced glue from a known working ST and it's all good! So I had 2 bad glue chips, in different ways.
That Atari diag cart could be inserted upside down, ask my old colleague how he knows!!
LOL =D
I hate taking Atari St's apart - too many screws and shielding.
Me too lol! It just takes so much time =/