Help needed urgently!

Problems with your machine in general.
BrettRogersUK
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Re: Help needed urgently!

Post by BrettRogersUK »

rubber_jonnie wrote: Fri Nov 26, 2021 5:37 pm Het @BrettRogersUK , sorry to say, mine is fixed, there was a broken pin I'd not seen on account of it being very small and my eyes being a bit old and crap!! Details over on the thread.
Hi,

Glad to hear you're all sorted. I'm going to have another look at mine and check all address and data lines again. Can't really do much else due to PS issue. I've not got an adequate enough bench PS to use for testing it so that'll have to wait until the PS is serviceable again.

Regards,

Brett
BrettRogersUK
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Re: Help needed urgently!

Post by BrettRogersUK »

Hi All,

I think I may have solved it, but until the power supply gets sorted out I won't be able to test it. I decided to redo the continuity test on all data and address lines and I found that Data Line D12 was getting any continuity at all through to the CPU, Blitter chip, Keyboard chips etc. So I remade the connection to the nearest point and now I get continuity from D12 to all parts of the board that it is supposed to be connected to.

So, Fingers Crossed, I may have solved my problem. All other data and address lines all check out everywhere they go. I took my time and did them one by one from the TOS switcher and D12 was the only one that wasn't getting any continuity anywhere.
sporniket wrote: Fri Nov 26, 2021 4:04 pm Hi, you may also have a look at my conversion of the STE schematic
https://www.exxosforum.co.uk/forum/viewt ... =31&t=4584

The kicad project is standalone (all custom libraries & footprint included), and there is an approximative PCB reconstruction (a given trace is going through the same way point, e.g. "between those component legs" kind of approximation.)

I hope that it would help.
Many Thanks for this also, it helped out a lot finding where D12 actually connected to.

Regards,

Brett
BrettRogersUK
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Re: Help needed urgently!

Post by BrettRogersUK »

sporniket wrote: Fri Nov 26, 2021 7:53 pm great :) finger crossed for the future test.
Just used an old ATX Power supply I salvaged from an old Dell Dimension PC. Just to see if I could get it to power up.

It boots into the desktop now but the display was pretty flakey and that's using a Monitor to scart cable or RGB to scart cable. I'm guessing thats the power supply that's causing that but it does boot into the desktop. I'll have to reattach the switch to the switcher now. My recap kit for the power supply was dispatched today so hopefully that'l be with me soon and then I've got some F2A 250v Glass fuses as well to be delivered. So hopefully soon I'll have a working computer again.

Thanks,

Brett
Steve
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Re: Help needed urgently!

Post by Steve »

Nice one Brett glad you got it sorted :)

Don't forget when you recap your Atari PSU, if you want to test it before using it in the machine remember to use a load. I use the load resistors Exxos sells just to check the 5v and 12v before reinstalling.
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rubber_jonnie
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Re: Help needed urgently!

Post by rubber_jonnie »

Glad you found that bad data line and were able to get it powered up, mine was an address line, but I had 2 data lines break on a Mega once.

Fingers crossed you can get the PSU sorted, but as Steve says, test it with a load first, and like Steve I also use the load resistors from exxos store.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
BrettRogersUK
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Re: Help needed urgently!

Post by BrettRogersUK »

rubber_jonnie wrote: Fri Nov 26, 2021 11:21 pm Glad you found that bad data line and were able to get it powered up, mine was an address line, but I had 2 data lines break on a Mega once.

Fingers crossed you can get the PSU sorted, but as Steve says, test it with a load first, and like Steve I also use the load resistors from exxos store.
Yeah, I will look at the dummy load resistors, last thing I want is to put it back in the case switch it on and it all go bang again after the work I put in finding the fault in the first place. 😆😆😆, I'll take my time with the caps and bridge rectifier. Making sure they're all sound and I'll also reflow other joints on the bottom of the ps board too just to be safe that there's no dry joints. Bit of belt and braces.

I did think I'd checked all the data lines but obviously must have missed that one, probably getting late in the night and getting frustrated. Anyhow, it seems to be fixed (famous last words and all that 🤣🤣🤣🤣)

Thanks again,

Brett
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rubber_jonnie
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Re: Help needed urgently!

Post by rubber_jonnie »

BrettRogersUK wrote: Sat Nov 27, 2021 12:52 am
rubber_jonnie wrote: Fri Nov 26, 2021 11:21 pm Glad you found that bad data line and were able to get it powered up, mine was an address line, but I had 2 data lines break on a Mega once.

Fingers crossed you can get the PSU sorted, but as Steve says, test it with a load first, and like Steve I also use the load resistors from exxos store.
Yeah, I will look at the dummy load resistors, last thing I want is to put it back in the case switch it on and it all go bang again after the work I put in finding the fault in the first place. 😆😆😆, I'll take my time with the caps and bridge rectifier. Making sure they're all sound and I'll also reflow other joints on the bottom of the ps board too just to be safe that there's no dry joints. Bit of belt and braces.

I did think I'd checked all the data lines but obviously must have missed that one, probably getting late in the night and getting frustrated. Anyhow, it seems to be fixed (famous last words and all that 🤣🤣🤣🤣)

Thanks again,

Brett
FYI when you're recapping, the legs on the replacement bridge rectifier require you to open up the holes in the PCB. Be VERY careful when you do this as it is quite easy to lift the tracks on the PSU PCB.

Again, it can easily be fixed if you do, but better to not do so in the first place.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
BrettRogersUK
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Re: Help needed urgently!

Post by BrettRogersUK »

I've got a DSP-508A. I've been looking at the fitting instructions for the psu recap kit and it says that the holes didn't need drilling out.

Thanks. I know they do on certain psu's but not this one.
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rubber_jonnie
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Re: Help needed urgently!

Post by rubber_jonnie »

BrettRogersUK wrote: Sun Nov 28, 2021 11:40 am I've got a DSP-508A. I've been looking at the fitting instructions for the psu recap kit and it says that the holes didn't need drilling out.

Thanks. I know they do on certain psu's but not this one.
They won't need drilling out for the caps, no, but they 'might' for the bridge rectifier if it's one of exxos kits.

I've had to expand the holes on every last rectifier I've replaced, including DSPs, so just letting you know it can be a gotcha. If you aren't replacing the rectifier, you probably should.

Another gotcha on these PSUs, especially the ones with the brown phenolic style PCBs is that they can be very sensitive to heat, so if you aren't using a desoldering gun, just be careful as it is very easy to lift the pads.

I speak from bitter experience.............. :pullhair:
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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