Atari 400 PSU - Help needed

[PuddyTat]

Pic of the recapped PSU.

Will give an update once the components arrive and are fitted.

@rubber_jonnie I like the Traco power personally and have used them on both the ZX81 and Spectrum. Not tried these yet but there's time!

400 PSU.jpg

[rubber_jonnie]

@rubber_jonnie

These are amazing to switching replacements

35a3e2c7-e7aa-42f6-ab26-6e9d74440860_1.daf28efa48d6b795072fce90f6f9f9cf.jpeg.jpg

Tom

Yeah, I've been seeing these of late, run cool and work really well. There is so much awesome stuff about now to keep our retro gear going :)

[rubber_jonnie]

Pic of the recapped PSU.

Will give an update once the components arrive and are fitted.

@rubber_jonnie I like the Traco power personally and have used them on both the ZX81 and Spectrum. Not tried these yet but there's time!

Looking good, I'll be really interested to see it running when you're done :)

Are you planning any upgrades like Incognito?

[PuddyTat]

Looking good, I'll be really interested to see it running when you're done :)

Are you planning any upgrades like Incognito?

This will remain stock at the moment and have refurbed two 410s to go with it, however that's not to say I won't look at adding something in the future!

[rubber_jonnie]

Looking good, I'll be really interested to see it running when you're done :)

Are you planning any upgrades like Incognito?

This will remain stock at the moment and have refurbed two 410s to go with it, however that's not to say I won't look at adding something in the future!

Cool :)

I must confess I can't remember the last time I used a cassette drive, and I have 2 1010s and an XC12. I tend to use either my SDriveMAX, SIO2SD, Uno Cart or my main go to, the SIDE3 cart.

I really want an 800, but prices at the moment are just crazy!! I have an 800XL with Ultimate 1MB, VBXL and PokeyMAX. My 65XE has the same upgrades, but just waiting on the PokeyMAX to arrive. Stereo Pokey is something to behold, some of the demos are something else and make the SID sound like a Spectrum IMHO :) Atari did a truly superb job with the 8 bit range, they are truly the forerunners of the Amiga.

[PuddyTat]

Cool :)

I must confess I can't remember the last time I used a cassette drive, and I have 2 1010s and an XC12. I tend to use either my SDriveMAX, SIO2SD, Uno Cart or my main go to, the SIDE3 cart.

I really want an 800, but prices at the moment are just crazy!! I have an 800XL with Ultimate 1MB, VBXL and PokeyMAX. My 65XE has the same upgrades, but just waiting on the PokeyMAX to arrive. Stereo Pokey is something to behold, some of the demos are something else and make the SID sound like a Spectrum IMHO :) Atari did a truly superb job with the 8 bit range, they are truly the forerunners of the Amiga.

I don't want to breach any forum rules, so I'll ping you a PM with some info, however I was always an Amiga user back then. So being very new to the Atari range (bar the 2600 ofc!), it's all new to me.

I was lucky to pick this 400 up with 7 carts, boxed paddles and manuals for less than £100 delivered, however was untested as no external PSU. Got the 410s later with some tapes to try them out so just need to get this board testing correctly to *hopefully* see if the 400 comes alive, or if I have more of a headache. Time will tell though as I'm away for 2 weeks from the 9th and have a kinda time limit so would like to see it working well before then if at all possible.

Yeah, prices have gone crazy across the board recently, though there's still a bargain to be had if you look hard enough and have the patience. Will get the drives and other bits when they come up again :D

[rubber_jonnie]

Cool :)

I must confess I can't remember the last time I used a cassette drive, and I have 2 1010s and an XC12. I tend to use either my SDriveMAX, SIO2SD, Uno Cart or my main go to, the SIDE3 cart.

I really want an 800, but prices at the moment are just crazy!! I have an 800XL with Ultimate 1MB, VBXL and PokeyMAX. My 65XE has the same upgrades, but just waiting on the PokeyMAX to arrive. Stereo Pokey is something to behold, some of the demos are something else and make the SID sound like a Spectrum IMHO :) Atari did a truly superb job with the 8 bit range, they are truly the forerunners of the Amiga.

I don't want to breach any forum rules, so I'll ping you a PM with some info, however I was always an Amiga user back then. So being very new to the Atari range (bar the 2600 ofc!), it's all new to me.

I was lucky to pick this 400 up with 7 carts, boxed paddles and manuals for less than £100 delivered, however was untested as no external PSU. Got the 410s later with some tapes to try them out so just need to get this board testing correctly to *hopefully* see if the 400 comes alive, or if I have more of a headache. Time will tell though as I'm away for 2 weeks from the 9th and have a kinda time limit so would like to see it working well before then if at all possible.

Yeah, prices have gone crazy across the board recently, though there's still a bargain to be had if you look hard enough and have the patience. Will get the drives and other bits when they come up again :D

I've replied to your PM :)

You'll find the Ataris very satisfying to fix and use :)

[PuddyTat]

So, time for an update.

Replaced CR201 - No change.
Replaced CR202/CR203 - No change.
Replaced LM7805 with a Traco Power 1-2450 - worse (10v and climbs!)

Current Voltages
Output at LM7805 is 6v, not 5v
Output at LM7812 is 3.9v not 12v
-5v reads as -12v on header
GND reads as -7v on header
Voltage at Bridge Rectifier is just over 7v DC
Input voltage is 12vAC

I can replace the bridge rectifier diodes next however any further suggestions? Anyone got a 400 PSU board they are willind to read the voltages off under no load? Not even the RF modulator board is currently plugged in.

[PuddyTat]

Thinking about this, the -7v at ground is bothering me. If ground were correct, then the -5v and +12v would read correct and the 6v at 5a and 5b could be attributed to having no load. Or is my thinking flawed?

[Tomswork]

No you are correct that is why I suspect a bad diode. But I guess a capacitor could be bad even when new also look carefully for solder bridges maybe ipa and toothbrush scrub

Tom