ROMBO ROMBOX - MF2 -512K RAM card no longer seen by the CPC 6128 edge connector

[DR400]

Hi, I have 3 CPC 6128's,  recently one has developed a fault where my ROMBO ROMBOX and MF2 and 512K RAM board are no longer detected, all 3 work 100% on the two other 6128's. 

When I run a |manicminer or similar command to a run ROM, nothing happens, the MF 2 is not detected , but the reset switch works.

All the edge connectors are OK, connecting cables all good, so far I have swapped a Z80 from working 6128, same result. Using modern stable 5V 2A PSU (no 12v as Gotek's in use)

What would you suggest to try next?  (have de-solder station etc. so happy to chip swap etc.)

TIA

Robin

[Rabs]

Hi, I have 3 CPC 6128's,  recently one has developed a fault where my ROMBO ROMBOX and MF2 and 512K RAM board are no longer detected, all 3 work 100% on the two other 6128's.

When I run a |manicminer or similar command to a run ROM, nothing happens, the MF 2 is not detected , but the reset switch works.

All the edge connectors are OK, connecting cables all good, so far I have swapped a Z80 from working 6128, same result. Using modern stable 5V 2A PSU (no 12v as Gotek's in use)

What would you suggest to try next?  (have de-solder station etc. so happy to chip swap etc.)

TIA

Robin

Sounds odd. I would still suspect the edge connector. Are you able to check continuity?

[Audronic]

Hi, I have 3 CPC 6128's,  recently one has developed a fault where my ROMBO ROMBOX and MF2 and 512K RAM board are no longer detected, all 3 work 100% on the two other 6128's.
All the edge connectors are OK, connecting cables all good, so far I have swapped a Z80 from working 6128, same result. Using modern stable 5V 2A PSU (no 12v as Gotek's in use)

What would you suggest to try next?  (have de-solder station etc. so happy to chip swap etc.)
Robin

Hi Robin.
Can you check the +5 voltage at perhaps the 512k Ram Board at power up (Please don't try to run any program)
as i think that a 2 Amp Power supply may not have enough current available,

Keep Safe

Ray

[DR400]

Hi, I have 3 CPC 6128's,  recently one has developed a fault where my ROMBO ROMBOX and MF2 and 512K RAM board are no longer detected, all 3 work 100% on the two other 6128's.

When I run a |manicminer or similar command to a run ROM, nothing happens, the MF 2 is not detected , but the reset switch works.

All the edge connectors are OK, connecting cables all good, so far I have swapped a Z80 from working 6128, same result. Using modern stable 5V 2A PSU (no 12v as Gotek's in use)

What would you suggest to try next?  (have de-solder station etc. so happy to chip swap etc.)

TIA

Robin

Sounds odd. I would still suspect the edge connector. Are you able to check continuity?

Thank you for the reply, have tested the edge connector with AVO meter, all traces from the point where the optional 50 way centronics connector can be fitted to the edge of the board all read 100%

[DR400]

Hi, I have 3 CPC 6128's,  recently one has developed a fault where my ROMBO ROMBOX and MF2 and 512K RAM board are no longer detected, all 3 work 100% on the two other 6128's.
All the edge connectors are OK, connecting cables all good, so far I have swapped a Z80 from working 6128, same result. Using modern stable 5V 2A PSU (no 12v as Gotek's in use)

What would you suggest to try next?  (have de-solder station etc. so happy to chip swap etc.)
Robin

Hi Robin.
Can you check the +5 voltage at perhaps the 512k Ram Board at power up (Please don't try to run any program)
as i think that a 2 Amp Power supply may not have enough current available,

Keep Safe

Ray

Thank you Ray for the reply, I tested all 3 with my bench PSU, the max current draw on the working ones with MF2 saving to the Gotek was about 1.4 amps, the 'faulty' 6128 had a max of 1.25 saving a basic file to the gotek, also tested with the ZX Spectrum +3 PSU modded to used the 5 & 12V, but same results 

[GUNHED]

Green Screen? Weak PSU? 2 A only? The PSU is weak then. 
Even if you seen to need only 1.x A from a 2 A PSU the Volts may (or even will) drop too much.

So, yes, one idea is to get a stronger PSU with 5V and 4-5A.

IMHO 2-3 A would be fine _IF_ the Volts are stable around 5. Volts below 4.5 _WILL_ make problems.

Good luck! 

[Audronic]

@DR400 

Hi Robin

If you have Checked all of the main causes. Then :-
Do you have Noels Diag ?
( I put one in a Lower rom Diagnostic card)
If so check the checksum of the ROMS
Perhaps the only other thing is the ROM has a weird fault.
Thanks

Keep safe
Ray

[Audronic]

@DR400 

Photo of ROM Checksums


Good luck

Keep Safe

Ray

[Rabs]

the MF 2 is not detected , but the reset switch works.

By "not detected", I guess you mean when you press the STOP button on the MF2, nothing happens at all and the CPC carries on as normal. Very Odd, I would at least expect some reaction.

I would check in the first instance that you see the NMI occurring when you press STOP on the MF2 (or at least check continuity back to the Z80).

I have recently re-drawn MF2 schematic and attached this below in case it helps (this was re-drawn from the Jose Leandro schematic on the CPCWiki).

You cannot view this attachment.

[DR400]

So, yes, one idea is to get a stronger PSU with 5V and 4-5A.

IMHO 2-3 A would be fine _IF_ the Volts are stable around 5. Volts below 4.5 _WILL_ make problems.

Good luck! 

Hi, The bench PSU have can give 5A and 30v, I upped the volts to 6, and set current limit to 3A, but on all 3 6128's, the max current draw is 1.47A, I checked the 5V rails and all show 5V
Regards
Robin

[DR400]

@DR400

Hi Robin

If you have Checked all of the main causes. Then :-
Do you have Noels Diag ?

Hi Ray, I have used Noels diags with my Dandanator, but as no devices recognised on the faulty 6128 so need to go internal!, could I follow this guide ROM REPLACEMENT (by Bryce )and burn a copy of Noel's diag to see if anything is found?

Regards
Robin

[Audronic]

@DR400 

Hi Robin

My tests were done with a LowerRom Board
which plugs in the expansion bus

Or :-"An other board "DiagRom" is designed by SerErris

check out cpcwiki forum message msg224409

It probably is worth making up one of these as they work Well.

Keep Safe

Ray

[Audronic]

OOps it did not load the Photo

[SerErris]

Looks great in red :-)

[Audronic]

@SerErris

I think its one of yours

Ps It works well
Also it is very Fast compared to the one Bryce produced years ago (Which also works well)

Thanks for the 2022/3 version

Keep Safe

Ray

[SerErris]

What do you mean, it works fast? How could a ROM board be fast or slow? 

[Audronic]

When it scans the ROM Slots it reads slot 0 and then quickly goes down to slot7 much faster than Bryce's version
That's all i meant

Keep Safe

Ray

[SerErris]

Ah I see,

thanks for the flowers, but that is actually @llopis work. I have only designed the hardware. The Software is the key here.