Unable to format microdrives

[martyn_hill]

Hi Bytesguy!

OK, so I'm stumped, but still thinking...

That your vDrive formats indicates that the digital signalling from the 8302 is all-good.

Back to you once I've pondered some more...

[tofro]

Can you, just to sort that out, go back to the old 7805 regulator and see if you get something working?

Some mainboard revisions simply become upset when confronted with the spikes a switching regulator tends to create.

Tobias

[Bytesguy]

Thanks Martyn It's a tricky one!

Tobias, I only just switched the regulator out so I don't think it's that, haven't noticed any changed since changing it. I could change it back to check, but it's a bit of hassle

[Bytesguy]

Some further digging this evening. I have been probing the signals as best I can and so far can see that the write signals appear to be working fine. I am wondering about replacing the ZX8301 and the 8049 just to rule out issues with those...

[Bytesguy]

I'm back with an update!

So I have replaced the CPU, ZX8301, ZX 8302 and the 8049 and TR3 all with no luck, still getting format failed. I have ordered a couple of microdrive ULAs from Rich so I will try and replace those when they arrive and see how it goes!

Meanwhile, I have acquired a second QL. I have yet to open it to check everything out, but I have had a quick play with it just now and MDV1 works flawlessly, formats reads and writes fine (on to the same cartridges I was trying to format on the other unit). MDV2 doesn't seem so happy and also produces the format failed error and has trouble reading - I will be giving everything a good clean (hopefully contact cleaner will work for the tape head as isopropyl is like hens teeth due to the current situation).

I will now be able to compare scope traces from the working unit which will be great for helping diagnose the issue further!

[martyn_hill]

Hi Bytesguy!

In addition to my PM of earlier today, I'd recommend you testing one of the suspect MDV units in the position of MDV#1 of the second QL. It is highly unlikely to cause damage to the QL, and would quickly confirm whether or not the first QL mainboard was contributing to the MDV format failures (I doubt it myself).

In all likelyhood, the suspect MDV unit(s) will still fail to format in this known-good QL mainboard.

You are safe to remove MDV#2 during the tests, so that only the unit being tested in slot#1 is in scope - with the MDV#2 unit removed, there is almost zero chance of a faulty MDV#2 drive cct (on the maonboard) from interfering with an MDV in slot#1.

Regards

[Bytesguy]

Hi Bytesguy!

In addition to my PM of earlier today, I'd recommend you testing one of the suspect MDV units in the position of MDV#1 of the second QL. It is highly unlikely to cause damage to the QL, and would quickly confirm whether or not the first QL mainboard was contributing to the MDV format failures (I doubt it myself).

In all likelyhood, the suspect MDV unit(s) will still fail to format in this known-good QL mainboard.

You are safe to remove MDV#2 during the tests, so that only the unit being tested in slot#1 is in scope - with the MDV#2 unit removed, there is almost zero chance of a faulty MDV#2 drive cct (on the maonboard) from interfering with an MDV in slot#1.

Regards

THanks Martyn for the informative PM! I will get back with my findings as I tinker with both QLs this weekend. In the process of giving the new QL a deep clean. There was so much dust under the key caps

[Bytesguy]

Wanted to post an update here! I renewed all the transistors and diodes which are involved in the microdrive operations and now I have a fully working QL! Both drives format fine, though MDV2 is a little on the slower side (not always a bad thing).

I did the same on my other QL but unfortunately it seems to be getting even more inconsistent with formatting (MDV1 is a bit 50/50 while MDV2 is a total failure). Still not sure what is happening there but continuing to investigate

[SH1]

Hello Byteguy,

Thank you for all this information, which is going to help me in fxing mine.

My MDV1_ just spins. MDV2_ is fine. I have swapped them around and bought two new old stock drives. All four of them work, but not in the MDV1_ slot.

My next step was to replace the ZX8302, which is currently on its way to me, complete with the modification.

If that does not do the trick, which Transaistors and Diodes did you replace?

Regards
SH

[Bytesguy]

Hello Byteguy,

Thank you for all this information, which is going to help me in fxing mine.

My MDV1_ just spins. MDV2_ is fine. I have swapped them around and bought two new old stock drives. All four of them work, but not in the MDV1_ slot.

My next step was to replace the ZX8302, which is currently on its way to me, complete with the modification.

If that does not do the trick, which Transaistors and Diodes did you replace?

Regards
SH

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!