The Sinclair QL Forum

Hello Byteguy,

Thank you. I shall start ordering the parts, which may take a while, presently.

Shall keep you posted.

Regards
Simon

Bytesguy wrote:
Evening! So the diodes were D17 D28 and D16. I also replaced TR3 TT4, TR5, TR6 and TR7. Some of those are for MDV2 so may not apply to you but probably won’t harm to replace them!

I’m still baffled why my other QL is wonky but I may just give up on it for now!

Hi,

Are you able to measure the components replaced to see if there is any degradation?

Derek_Stewart wrote:

Bytesguy wrote:a

Evening! So the diodes were D17 D28 and D16. I also replaced TR3 TT4, TR5, TR6 and TR7. Some of those are for MDV2 so may not apply to you but probably won’t harm to replace them!

I’m still baffled why my other QL is wonky but I may just give up on it for now!

Hi,

Are you able to measure the components replaced to see if there is any degradation?

I didn’t do a very good job of removing them to be honest so they got quite beaten up and I chucked them out. It seemed to work after I replaced the diodes and TR6 and TR7, so just replacing the other transistors alone was not enough.

I seem to have possibly cured the other QL by pulling out the TSR 2450 regulator and reverting back to a (new) 7805. After replacing it seems MDV1 is back to fully working and MDV2 does format most times but occasionally fails to - good enough for me!!

I’ll do some more testing later on to confirm that, hopefully it wasn’t just a fluke. It leads to me believe there was some switching noise affecting the micro drive ULAs possibly

Hi Bytesguy!

Well, that was something of an adventure, wasn't it!

Some of those switching regulator replacements can certainly be noisy and, given the closer proximity to the MDV in slot#2 versus slot#1, coupled with (typically) the MDV in slot#1 having a simple shield around the ULA, the end result would certainly be consistent with the various symptoms you've observed over time.

Good luck!

It may even be that replacing the components has made better solder joints and you may have 'cured' a dry joint in the process. Poor solder connections can act like all sorts of components, and the behavior is unpredicatble.

martyn_hill wrote:Hi Bytesguy!

Well, that was something of an adventure, wasn't it!

Some of those switching regulator replacements can certainly be noisy and, given the closer proximity to the MDV in slot#2 versus slot#1, coupled with (typically) the MDV in slot#1 having a simple shield around the ULA, the end result would certainly be consistent with the various symptoms you've observed over time.

Good luck!

It certainly has been It's still not perfect but I am leaving well alone now, I never want to see the inside of these QLs again Yes like you my thought was the switching noise near the ULA of MDV2 was having a major effect on it's performance, also partially on MDV1. Sometimes the old ways are the best ways eh

Pr0f wrote:It may even be that replacing the components has made better solder joints and you may have 'cured' a dry joint in the process. Poor solder connections can act like all sorts of components, and the behavior is unpredicatble.

It could have been, though I did inspect the joints beforehand and couldn't see anything visible, though that's not to say there wasn't something I missed! I resoldered the power sockets on both as they were a little loose and flaky, nice and strong now! Really glad I invested in a proper desoldering station

Bytesguy wrote: I seem to have possibly cured the other QL by pulling out the TSR 2450 regulator and reverting back to a (new) 7805. After replacing it seems MDV1 is back to fully working and MDV2 does format most times but occasionally fails to - good enough for me!!

I’ll do some more testing later on to confirm that, hopefully it wasn’t just a fluke. It leads to me believe there was some switching noise affecting the micro drive ULAs possibly

Hi,

The TSR-1-2450 is 5V @ 1A and the 7805CV is 5V @ 1.5A, clearly the QL is running out of power from the TSR-1-2450

There is a TSR-2-2450, which is 5V @ 2A ouput, but is twice the price.

Derek_Stewart wrote:

Bytesguy wrote: I seem to have possibly cured the other QL by pulling out the TSR 2450 regulator and reverting back to a (new) 7805. After replacing it seems MDV1 is back to fully working and MDV2 does format most times but occasionally fails to - good enough for me!!

I’ll do some more testing later on to confirm that, hopefully it wasn’t just a fluke. It leads to me believe there was some switching noise affecting the micro drive ULAs possibly

Hi,

The TSR-1-2450 is 5V @ 1A and the 7805CV is 5V @ 1.5A, clearly the QL is running out of power from the TSR-1-2450

There is a TSR-2-2450, which is 5V @ 2A ouput, but is twice the price.

Hi Derek, I just double checked and it was actually a TSR-2 I fitted to this one. The TSR-1 is the model I was fitting to my ZX81s (no problems with them!)

Maybe I was unfortunate to get a duff one? I’ll stick with the 7805 as it works the best

Hi,

I have removed my QL regulator and heat sink and replaced it with the Tetroid Power Regulator replacement board:
https://www.sellmyretro.com/offer/detai ... -%29-28469
The QL is running ultra cool, even with a Super Gold Card fitted.

Derek_Stewart wrote:Hi,

I have removed my QL regulator and heat sink and replaced it with the Tetroid Power Regulator replacement board:
https://www.sellmyretro.com/offer/detai ... -%29-28469
The QL is running ultra cool, even with a Super Gold Card fitted.

Interesting! I have some of tetroid's stuff, always good quality. Might give this a go!