Replacement supply for Mega STe

[Randy]

I am looking for a replacement supply for my Mega STe as the old one is "pulsing" and I can't find the fault, even after hours of video instruction and parts testing/replacing, only thing left is the transformer, which I may pull and test.  So I am looking at the Meanwell RB-85Q, size is good, has all the right voltages and current outs, just missing the PG line, any suggestions or ideas?  Thanks

[MasterMotorola]

Randy, I can't seem to find the RB-85Q model, are you sure that's the right number?  The Mean Well RT-65B is a perfect match for the MegaSTE and TT.  Add a Noctua NF-6Ax25 FLX fan if you don't have one already, it's the most silent fan you can get.

[Randy]

Hi Master, I listed the wrong model number, its a RQ-65B, the RT-65B won't work as it doesn't have a -5v rail, which is present on the 5341 and the connector plug into the Mega STe.  Still missing the PG line, but I guess I can just wire that to the +5 rail, correct?  And yes, I do have a Noctua fan ready to go!

[MasterMotorola]

Randy, looks like we both got the models mixed up... the RT-65B is good for the later MegaST2/4 computer that use more than 40W.  A new PSU for my TT is the next thing I will get.  I would have had it a while ago but I opted to get a RAM upgrade instead.

[saulot]

I've checked RQ-65B plate and compared it with Atari TT Service manual specs. And +5V line RQ-65B provides 6amps, service manual states that 7amps are needed. MegaSTe has the same requirements (also checked service manual). Every other parameter is ok. But I'm not sure how relevant it is nowadays with modern storage options (most are not very power hungry), might be different with alot of devices connected. So, I think RQ-85B would be a safer bet. On the other hand RQ-65B specs page says that +5V line can work in range of 0-8A.

Edited May 12, 2021 by saulot

[Randy]

8 hours ago, saulot said:

I've checked RQ-65B plate and compared it with Atari TT Service manual specs. And +5V line RQ-65B provides 6amps, service manual states that 7amps are needed. MegaSTe has the same requirements (also checked service manual). Every other parameter is ok. But I'm not sure how relevant it is nowadays with modern storage options (most are not very power hungry), might be different with alot of devices connected. So, I think RQ-85B would be a safer bet. On the other hand RQ-65B specs page says that +5V line can work in range of 0-8A.

I think you are correct, if one uses a Gotek and Ultra Satan the main power draw would be significantly reduced and therefore the current required would probably be easily handled by the RQ-65B, thanks.