Another Egyptian Enterprise 64

[rubber_jonnie]

OK so the comp mod is off and I'm now testing with this that arrived today:

PXL_20261106_152035983.jpg (314.55 KiB) Viewed 49 times

PXL_20261106_152045169.jpg (277.91 KiB) Viewed 49 times

It's very neat and I'm pretty pleased with it, but it turns out the one LR1220 battery I have is dead, so it's forgetting the time!!!

Better go and order some.

[PhilC]

Looks good. Good job I ordered some 1220s last week then.

[rubber_jonnie]

Looks good. Good job I ordered some 1220s last week then.

Hmm, I just checked and the battery has 3.1v which should be fine so I've asked the guy who sent it because there may be some other way to set the cart and I'm not doing it right.

[rubber_jonnie]

So he got back to me and confirmed that the clock has to be set once the date & time are set.

So to set the time you use the :time command, and for the date it's the :date command, much like in MSDOS.

However that needs to be written to the cartridge, and to do that issue the :hwrite command

All working for me now I have a battery in it.

The manual is here too for reference.

ENTERPRISE SD Premium-User Manual (UK).pdf

(220.57 KiB) Downloaded 9 times

!Message from: Moderator

@rubber_jonnie, we have placed your attachments in-line so they display correctly in your post. Here's the how-to guide.

[rubber_jonnie]

Well, more magic smoke here just now as the Enterprise toasted another BC337.

Enterprise number 2 continues to function normally.

Having done all the good things suggested over at the Enterprise forum I'm a bit stuck, not least as I'm out of BC337s and waiting on an order to arrive.

Perhaps I need to go down the route of replacing the circuit entirely with something else that doesn't toast BC337's all day long.

Clearly the LM7812 is OK as that hasn't been replaced and continues to work when the BC337 is replaced.

Very annoying since BC337s have a particularly rancid magic smoke...

It was kind enough to let me test the Enterprise with both the SD cart and FDD controller in use at the same time and the combination is great!

[rubber_jonnie]

So by way of an update, I had some replacement BC337's arrive yesterday and fitted one as I was keen to see how the machine behaved. It's now got through at least 6 BC337's.

Just a reminder, this machine had been in a flood and contained silt and took a lot of cleaning.

Whilst I did give L1 a cursory clean at the time, it looked fine so I left it, though it was subsequently removed and all the solder for this circuit removed and re done. I cleaned under all the components when I removed them for re-soldering.

However at no point did I clean the coils as they looked OK. So I did this with some IPA and a toothbrush whilst I waited for the transistors to arrive.

I fitted the transistor yesterday and did some monitoring and found the following after a few hours running:

C10 sitting steadily at 15 V
78L12 (U21) input around 15 V (Same as C10)
78L12 (U21) output 12 V
78L12 (U21) around 60°C
TR2 and TR3 around 45°C

Ambient temp yesterday in my office was around 24C-26C BTW.

So nothing here shouts that TR2 is in trouble.

I have tried to force it to fail, which usually happens during a power cycle, but it just won't fail now. I'm going to keep at it as it's run for days in the past before failing and I'd like to see if I can measure a voltage spike if it fails.

Conclusions so far are that the BC337s I had were either marginal of fakes, or that by cleaning L1 carefully I've dislodged something that caused some sort of failure mode in it.

Since the BC337's have been in my parts drawer and were bought years ago, I can't vouch for their authenticity or suitability for the job as TR2.

As for L1 there was nothing particularly obvious on there but there could have been something.

I'm slightly kicking myself for changing 2 things at once - I troubleshoot systems for a living and broke my own cardinal rule...

Nonetheless I am erring on the side of the BC337's being marginal since they all came from the same packet that I happened to have in my spares.

I'll keep trying to cause a failure and if I do I'll report back, but it could be a while.