Emulator II won't read floppies

[budney]

So I decided to bite the bullet and join the club   but obviously the EII I bought isn't working properly. It won't get past the insert diskette message. This is an early serial number, the floppy drives don't have their own power rail. This unit used to work until it was shipped overseas, when it arrived it wouldn't boot from any floppies.

PSU values are correct, resoldered the output wires on the psu, that didn't change anything. Im about to reseat every IC to see if that helps. I do plan on getting a HxC emulator but I'd like to get it up and running first before I shell out on a new drive. Tried cleaning the heads with some alcohol but they are very clean, the whole synth looks like it never left the studio. Unplugged all the connectors a few times as well but that didn't help either.

One weird thing I noticed is that when the LEDS on the drives are flashing the psu's 'tone' changes depending on which LED is lit. I insert a floppy in either drive and they try and do something for a while and the LEDS change sequence, but then after a while the drives just give up, and then the psu noise changes. Is this usual behaviour? If there is a problem with the psu I'd just replace it, but thats an extra cost I'd like to avoid since I'm quite poor after buying it in the first place...

I did manage once to get a disk read error, but that was the first time I powered it up. I've not managed to get that again since.

Any other tricks that I can try before having to buy some more hardware?

[dr.c]

Take off the mains plug. Open the machine, unconnect the power distribution (colored wires) from the power supply PCB, take off all its cables, dismount the PCB and look under.
At the Molex connector (where the colored wires go), some solders have may cracked. In this case, and finaly, in any case, desolder the connector pins, take off the old solder, and resolder it seriously.
The, have a look at the connctor with the wires. There is a great chance that at the yellow wire place, the pin have been overheating, and even, the plastic of the connector at this place, may be brown?

Clean the pins or change the connector. Reput everything in place, do not forget the voltage switdh selector wire, verify everything, verify your verification, and try.

Let us know !

[budney]

I've already checked that. This is an early psu, there isn't a molex connector the wires are soldered straight into the board. As I said I removed the old solder and resoldered, no change. The psu is making strange noises though depending on what the drives are doing. Nothing on the psu looks burnt or brown, the whole synth is in good cosmetic condition, hardly any of the ics are that oxidated. The other connector you mean is where mains comes into the psu? I haven't resoldered that but i assumed if the voltages were correct then the mains into the board isn't the problem.

I've ordered a HxC, but I would still like to get this up and running before it arrives.

[dr.c]

There was a Molex connector on every power supply, new or not. I started to fix EIII's at SN : 16 !!!

The PSU has apparently a need to be changed.

[budney]

Ah okay, so I guess someone has been here before me. Does this psu look out of the ordinary to you apart from lacking a molex?

So you think if I get a replacement psu it will work? Ideally if it's cheaper I would like to fix the original, although smps are very annoying

[dr.c]

Okay... Where is this machine coming from ? USA, Europe ?

You say the sound (noise) of the power changes depending what are the drives doing. Now, please, be attentive to what I write : this "sound", is it appearing in the electrical signal (only by the audio outputs), or can you hear it as well if the audio is disconnected ? Be carfefull, the metal parts you can see are LIVE with 480 volts ! DANGEROUS !

[budney]

this machine is in the UK

bit of an update, I ordered a HxC, but I am getting nothing from it. Occasionally if I power on with an SD card inserted it will stay on the boot in progress screen, if I eject the SD it will go to insert diskette, but loading images and files from the SD does nothing

I also ordered a mean well T60 psu. I installed that pretty easily, but still I am stuck on the insert diskette screen. The noise I was talking about earlier was coming from the old psu, I had nothing plugged into the audio outputs I am purely trying to get this thing to boot before I can even listen to it.

I have a scope and am preparing to start probing this beast but I don't know where to start looking.

One thing I have noticed, quite a few of the IC's on the digital board are getting rather hot, some too hot to touch. They are in the top row on the right of the digital board, IC's 150 to 155, is this normal?

[dr.c]

"I ordered a HxC,"  what is it ?

"One thing I have noticed, quite a few of the IC's on the digital board are getting rather hot, some too hot to touch. They are in the top row on the right of the digital board, IC's 150 to 155, is this normal?"

This is not normal. Okay, you've got a short circuit on the board, this is why the PSU is making noise.

Take off these circuits, put them appart, remembering where they were, and restart the machine.

Is the noise still there ?

What is the reference of these circuits ?

[budney]

Forgive the delay, I have only just got back from holiday.

A HxC is a floppy drive emulator to replace the use of floppies with an SD card. That doesn't want to boot either.

The circuits are

SN74S283N
AM2149-55DC

When I removed those circuits the noise did not go away.

I removed and put back in the Z80A SIO/2, that changed the psu noise completely, its now completely erratic and the floppy drives don't have any LEDs lighting up. Is it safe to assume that I will need a new Z80A SIO/2?
I tried with a replacement power supply but that didn't change anything.

[dr.c]

I wrote : "You say the sound (noise) of the power changes depending what are the drives doing. Now, please, be attentive to what I write : this "sound", is it appearing in the electrical signal (only by the audio outputs), or can you hear it as well if the audio is disconnected ? Be carfefull, the metal parts you can see are LIVE with 480 volts ! DANGEROUS !"

Can I have an answer ?   

[budney]

The noise that I am describing is not in the audio outputs. It is purely coming from the power supply.
I can hear it faintly and when I stick my ear by the power supply it is clearly audible. It sounds like the whine typically found from switching mode power supplies, often when they are faulty. I think it's coming from the transformer but i can't be certain, all I know is that the whine changes frequency depending on leds and booting times.

However now the leds on the drives do not light up at all, and it is stuck in boot in progress

[dr.c]

I can't believe this...

I write to you : "Be carfefull, the metal parts you can see are LIVE with 480 volts ! DANGEROUS !"

And you write : "I can hear it faintly and when I stick my ear by the power supply it is clearly audible."

Change the power supply.

[budney]

I was just trying to explain that the power supply is definitely the noise, by getting closer to it. I wasn't actually putting my head over the power supply that is downright crazy!

I had already replaced the original power supply, with a meanwell t60c which others on this forum have used as a replacement. However, that did not change anything, it still would not boot. This new power supply didn't make any noise but the problem was still there. You then asked if removing the ic's that were hot stopped the psu noise, so I put the orIginal one back in to test this. The original power supply was still making strange noises dependant on what leds were lit on the disk drives, regardless of what ic's I had removed.

So now, I have an eii that will not boot, with certain ic's getting hot. I am comfortable probing and using a scope, Im just not familiar with the old logic and architecture, so I have no idea where to start looking. I would normally take this to someone who knows about this but the only person even remotely close to me has stopped taking new orders as they are so busy.

Do you have any other ideas I could try? I would be very thankful if we could work this out together!

[dr.c]

You wrote : "I was just trying to explain that the power supply is definitely the noise, by getting closer to it. I wasn't actually putting my head over the power supply that is downright crazy!"
My answer : You would not believe what I saw in thirty years of repairs in the music business. For example, a guy who wanted to modify his E-Max II keyboard to 21" rack version has CUT it in three parts, including circuits, keyboard, everything, to finaly find out that the mains plug was on one mart, the outputs on another, and the display on the third one. I sent it to E-Mu because they didn't want to believe me.
So, nothing surprises me anymore, concerning the stupidity of certain people.

[dr.c]

To be serious : I think you should really wait till this service center you know can take your machine, its really too erratic.
I am sorry, but when I ask, for example : "Okay... Where is this machine coming from ? USA, Europe ?"
You answer : "The machine is in the UK", wich was not answering the question, wich was, again, and again : "Where is this machine coming from  ?
I didn't ask this to try to know if you have stole it from an eight year old handicaped little girl, or exchanged it with drugs, its just because there were a lot of different versions, I have a huge database of the machines I've fixed, along their serial number, versions, batches, board revisions, original owners and where they have been bough, wich are very precious infos to trace the breakdowns.
I cannot explain everytime, in detail, spend hours to explain why I ask this and the implications, spending my time by asking serious questions to obtain that kind of answers.
In clear, I've got better things to do out of my life.
Certain people say I am a jerk, a pretentious lunatic fat ass, but, curiously, after they have been repaired.

So, I suggest you take your ticket to the queue at the service center you know, this will save your time, and mine, as well.