exxos's Atari, Amiga & retro forum

I’ve put together a TF534 which is refusing to boot (not even DiagROM.)

If I clock jumper for 7mhz, I get the usual green flashing but it quits a few seconds in with a red screen and never outputs anything (is this position known to be non-working?) If I jumper for the oscillator, nothing happens other than a solid power light. I’ve tried 50,40,33,25mhz oscillators with the same result.

I can scope the buffers and ic5 shows the correct speed the oscillator is rated for, while ic4 shows the Amiga’s 7mhz.

I’ve replaced both cplds, probed the board several times over and the only thing I can find is that the bus cpld is shorted between pins 21,22,23 when the FPU is inserted. Is this correct?

My inverter is a 74ac16245dlr and reads “ic txrx non-invert 5.5v”, it is the only component I’m not quite sure is correct.

I can swap between this and a TF530 that works fine in this machine, fwiw, so the machine is otherwise up to it.

Thanks for any help in advance.

Does DiagROM output anything over the serial connection? If you don’t get the flashing I don’t think that it does, but just to be sure.

Nothing at all.

EzdineG wrote: 26 Mar 2019 08:58 I’ve put together a TF534 which is refusing to boot (not even DiagROM.)

My inverter is a 74ac16245dlr and reads “ic txrx non-invert 5.5v”, it is the only component I’m not quite sure is correct.

These are the ones i used.

https://uk.rs-online.com/web/p/bus-transceivers/6629382

The 7Mhz position should probably fail with a ram error. So you'd see some diagrom output. If you dont even get that you have something more fundamental wrong.

EzdineG wrote: 26 Mar 2019 08:58 My inverter is a 74ac16245dlr and reads “ic txrx non-invert 5.5v”, it is the only component I’m not quite sure is correct.

I am using digikey part number 296-4174-5-ND.

alenppc wrote: 26 Mar 2019 12:19

EzdineG wrote: 26 Mar 2019 08:58 My inverter is a 74ac16245dlr and reads “ic txrx non-invert 5.5v”, it is the only component I’m not quite sure is correct.

I am using digikey part number 296-4174-5-ND.

Thanks, Alen. It looks like the only difference between mine and yours is only the quantity and delivery mechanism of the chips. The part I ordered is a recommended alternative to yours when browsing it. Yours has the exact same description.

terriblefire wrote: 26 Mar 2019 10:26 The 7Mhz position should probably fail with a ram error. So you'd see some diagrom output. If you dont even get that you have something more fundamental wrong.

This is what I get at 7mhz. Always stops at the same place, and slight graphical corruption on Amiga screen: Amiga whitescreens with the jumper set to the proper position with no output through the serial.

And nothing @ 50Mhz?

terriblefire wrote: 26 Mar 2019 22:06 And nothing @ 50Mhz?

No, but embarrassingly the problem has now been solved; there was nothing wrong with the board.

I usually use pin headers to mount the cpu, but this time opted for one of these: Anyone see the problem? Thanks to Viktor for pointing out that i needed to add the missing pins. I should have known better :/

Thanks all for your help!

Ah yeah.. with the wrong headers you have missing power pins...