Compact xvi Red Zone Troubleshooting assistance needed

[sleepydwarf]

Hi All,

This is my first post, and so I must start by apologising for my first post being a cry for help.

I recently managed to buy a faulty compact red zone. Been keeping an eye out for one for sooo long and this one appeared on ebay and I managed to win it.

My thoughts were to give it a full re cap, replace SRAM battery and whatever else was needed and I would be good to go. Things did not go as planned sadly.

The original fault was when the system was turned on you would see the screen kick into life as though a signal was detected, but the screen remained black, every few seconds the screen would briefly show the standard insert disk message. If left the machine would continue to do this for however long it was left for. If at any point I press interrupt it would display the general error message which from some extreme searching seems to mean there has been a problem please reboot, commonly seen when SRAM errors occur. This error is displayed correctly, constant proper steady image. SRAM battery has been replaced, the system then allowed me to clear SRAM by holding down CLR at power up. The issue still remains though.

If a floppy disk is inserted the disk stays in and LEDs are red for a few seconds, then floppy light reverts to green and the screen is black, no image flashing, no sign of life at all except the screen is aware of a signal. If while it is in this state I press interrupt I get another error message. Try as I might with virtual Japanese keyboards and online translations I am getting no where in finding out what the error is, but it looks like the attached picture named error2.jpg

The machine has now been recapped, including the four caps in the floppy drives, the SRAM battery has been replaced also, however during this process I appear to have made things even worse. Due to a lapse in concentration one night I picked up the wrong bag of capacitors end result being that when replacing C29 and C31 I soldered 6.3v 47uf caps in place instead of 25v 4.7uf caps. Now while the machines behaviour seems to be the same as it was, there is now also a display issue. the error messages seem to be blurred really badly or almost have the appearance of being smudged. The second attached image shows it better than I can explain it and is called blurred SRAM.jpg, it is what the clear SRAM confirmation now looks like.

The caps are all now in correct places, but I have most likely caused damage due to my own stupidity.


So that's pretty much it, sorry it is such a long winded post but I have tried to be as detailed as I can be, any help would be greatly appreciated.


Many Thanks
Rob.

[lydux]

Hi Rob, and welcome to the wonderfull (or horrible) world of x68000 !

Your details are very good. I just have some more questions :
- Pictures you provide are from a CRT or LCD monitor ? (CRT I guess...)
- Have you try with another monitor ?
- What's the exact disk you've tried to get the first message ?
- Are you able to write your own disk ?

We'll try first to correct your blurry image issue.
Then the floppy one (because I'm sure it's a floppy drive issue).

[lydux]

My Compact is opened to make it sure. C29 and C31 are related to the sound amplification, nothing to do with video ! And they normally are 4.7uF/50V, but 25v should be ok.

The problem is somewhere else... Please make sure all replaced caps are soldered with respect of the polarity.

[sleepydwarf]

Hi lydux,

Thanks for the reply and the welcome.

Images are taken from an old Toshiba LCD TV connected to PC input via RGB to VGA adapter that came with my Expert HD,the tv displays the expert hd very apart from missing the bottom of the image. I have however tried with a CRT and also an old projector but giving same results regarding the initial black screen with insert disk message popping up every few seconds, and since the blur occurred
As for which disk I am not completely sure now, I tried a few so not sure which one I took the photo on. Disk I have tried have been Human302, and Tetris and a couple of other games. As for whether I am able to write my own disks, I would like to say yes but in all honesty I am just not sure. For 3.5" I have used both a Sony PCGA-UFD5 and a Toshiba PA3109U-1FF USB floppy drive, first formatted with "FORMAT A: /A:1024 /T:77 /N:8 /U" the process completes on both drives without error, then diskimg is used to write image to disk using HD to Floppy 125. As far as I can tell yes I can write my own disks but not sure if they work of course.

Caps I have checked and re checked given my recent stupidity of mixing up the caps I had the guide printed and checked each and every cap and polarity.  The I thought it was something to do with those caps is, I have through the whole re cap process replaced two or three, then powering up the machine to see if anything was different, when I saw the blur the last two caps I replaced were 29 and 31, looked at them a little more carefully and saw what I had done. Though the voltage may have been ok, would the fact that they were 47uf instead of 4.7uf cause any damage elsewhere.

Something else that I realised I didn't mention in my original post was that when this machine arrived the external HD or rather SCSI connector was a bit mashed. On checking pins for continuity to ground I found a short which didn't seem right at all as it was physically close to a ground plane but had no track to or from ground. Just in case the mashed socket was causing a problem I desoldered that from the daughterboard, thinking on it, that was around the time I mixed up the capacitors too.

Thanks again

Rob.

[sleepydwarf]

Just to be sure I have just checked all capacitors using a magnifying glass, all are correct polarity, also checked soldering, and the board in general with magnifying glass and all looks to be ok. No signs of bridging or solder splash anywhere, also no visual signs of any kind of damage.

Thanks again

Rob.

[caius]

Hi, IMHO the culprit is  the PSU, we know that problem in this component   can reflect in other sections (video, sound, floppy), I'd try a full recap of it or , better, a replacement with something of more reliable (miniATX PSU or Pico PSU).Master , correct me if I'm saying bullshits...

[lydux]

I don't think it's the PSU... I'm more thinking to something around the output of the video DAC (CXA1260Q).
But I don't have any schematics of this part, so I need to draw it myself.

Looks like capacitors on RGB output tend to have difficulty to (dis)charge...

Rob, I'm sure it's nothing serious. Don't worry about the mistake you've done, those capacitors are involved with the sound filtering and amplification. Placing wrong capacitor values can hardly damage something here. At worst, it would give you sound distorsion or no sound...

What you can do actually, if you can, is posting a good picture of your motherboard, the video output region : let's say the area between the video DAC (IC38) and the DB15 video output connector.
Then, try removing both floppy drives ribbon cable from the motherboard (yeah, remove both drives). See if you can get the fixed "Please insert a disk" message. Well, something that look likes...
As possible, I would also like another picture of a blurry image but with the whole screen this time (I want to see the border of your monitor).

[sleepydwarf]

Hi,

Thanks for your reply caius, I was beginning to wonder about PSU, that is one part of the system I have not re capped yet. Reason being when I opened it the PCBs look spotless, no sign of any kind of leakage, also looked untouched, unlike the mainboard which has been through a lot by the looks of it. I decided to check it with a meter and all lines were spot on voltage wise when I got it. Was going to re cap anyway, but need to crack it open as I don't know if any of the caps were SMT or if they are all  leaded. Will get onto that later on today, along with re checking voltage levels.

Thanks again lydux for your help also, have tried the machine both with and without floppy drives, neither the blurring issue or the original issue is altered by the presence of the floppy drives.

One thing I have noticed that makes a difference to the original issue at least is if the HC ribbon cable is not connected between mainboard and the daughterboard the machine would not flash the insert disk icon, I don't know if that is relatively normal on these machines? Will try and get some decent pictures taken later today, be warned you may need to prepare yourself for a shock, the board isn't great, and as I said above it looks like it has been through a lot. Granted I have probably not helped it much . When this first arrived the board looked like it was pretty much covered in a mix of flux and I assume cap leakage, I got more and more worried from that point on to be honest.

Anyways will try get pics sorted later today.

Thanks again for all help and suggestions, it is appreciated.

Rob.

[lydux]

One thing I have noticed that makes a difference to the original issue at least is if the HC ribbon cable is not connected between mainboard and the daughterboard the machine would not flash the insert disk icon, I don't know if that is relatively normal on these machines?

I was sure of this behavior ! Rob, this is the culprit of your first problem : one (or both) ribbon cable is bad. This is a well known issue with Compact models. One line on the cable is cutted or shorted, leaving a signal in an unwanted state. In your case : notifying the motherboard that a floppy is always inserted, so trying to load from it, but can't... As result, the message box keep flashing.
You'll have to find newer one once your blurry image will be fixed.

I do now have a schematics of the video DAC output (btw, thanks to x68030 service manual ) and a good understand on how this part works. I just need to verify something now...
You will probably require a voltmeter. Do you have one ? And know how to use it ?

[caius]

One thing I have noticed that makes a difference to the original issue at least is if the HC ribbon cable is not connected between mainboard and the daughterboard the machine would not flash the insert disk icon, I don't know if that is relatively normal on these machines? Will try and get some decent pictures taken later today, be warned you may need to prepare yourself for a shock, the board isn't great, and as I said above it looks like it has been through a lot. Granted I have probably not helped it much . When this first arrived the board looked like it was pretty much covered in a mix of flux and I assume cap leakage, I got more and more worried from that point on to be honest.

Anyways will try get pics sorted later today.

Thanks again for all help and suggestions, it is appreciated.

Rob.

Hi, did you mean the FFC cable wich carries the signals from the motherboard to  daughterboard?On this daughterboard there are two  white vertical connectors, one is marked 'HC' and through FFC cable carries signals from motherboard  to external SCSI connector, the other is labelled  'FD' that carries signals to external FDD connector.I attach  a picture for better understanding.

[sleepydwarf]

Hi,

Lydux, sorry not had chance to sort pics as yet, other things have had to take priority this evening im afraid. Yes have a multimeter, I am familiar with usage for voltage, amperage, resistance and continuity.

Caius, yes that is the cable I meant. If I leave either or both floppy drives disconnected it has no effect, if the ribbon cable for the external floppy connector on the daughterboard is disconnect it has no effect, but if the HC ribbon cable is disconnected the insert disk message that was flashing onto the screen every few seconds would not appear at all.


Thanks again

Rob.

[sleepydwarf]

Caius, looking at the picture that is the same daughterboard yes, with the exception of the pin sockets next to the white ribbon connectors, is it for internal SCSI?

Lydux, here are photos. Try not to cry when you see my appalling solder job. I am a bit unsure about C39, the positive pad was not present, along with the track the connected to it, it looks like it lead to a test very close, I had to carefully scrape PCB to reach copper, and had a hell of a job soldering to it, but it did seem secure before I soldered the negative side of the cap.

The other pic is the entire screen as requested, and it is the clear SRAM prompt again, or at least meant to be 

Thanks very much for helping

Rob.

[sleepydwarf]

Sorry forgot to add images DOH!

[caius]

Caius, looking at the picture that is the same daughterboard yes, with the exception of the pin sockets next to the white ribbon connectors, is it for internal SCSI?

Hi, yes, female headers are for internal SCSI--->IDE--->CF modification, I made this some time ago, here is the documentation:

http://gamesx.com/wiki/doku.php?id=x68000:internal_scsi_and_cf_card_mod

Regarding your motherboard recap, why did you choose again SMD electrolytic capacitors?You could have used SMT ones, soldering would have been more easy and clean like I have done for my CompactXVI.

[sleepydwarf]

ahh yes, I have that bookmarked, maybe for some point in the future. Came across it a while ago while searching for something.
I didn't know SMT could be used to instead of SMD to be honest. Didn't realise how "out of practice" I was with my soldering to be honest, Also in lots of places where tracks had been broken prior to me getting it they have been bridged with solder. I have checked for shorts both visibly using loupe and meter for continuity though.

If I can manage to get any kind of progress with the machine I may well replace with SMT at some point in the future, it will allow a proper cleanup of the board.

Thanks

Rob.

[lydux]

Recap is done, and as you have noticed, Compact PCB traces could be easily broken. So, no need to change them unless you have a good reason to do it again.

Anyway, time to do some measurements ! I need the input bias voltage on the video DAC :
Just keep the motherboard and the PSU, no need for the other parts. Turn it on, and put the black lead on any ground part (a connector shield for example), and the red one on pin 24 of the video DAC (IC38). It should be easy to perform as this pin is located on the IC corner. The expected result should be between 0.8 and 2v.

That's all for now.
I can't find C39 usage right now. I hope it's not involved with the video part... Will check this later.

[sleepydwarf]

Hi lydux,

Yes how right you are, to be fair if this machine lives again it is best I leave it well alone apart from putting back together of course. Its been through enough I think.

Ok Voltage reading at PIN24 of IC38 is 0.611V which is outside the range you state.

Just as I was there checked PSU voltages again, these are

GND-->0V
GND-->0V
PWRON-->1.5V
+5sb-->5.0V
-12-->-11.98V
+12-->11.96V
GND-->0V
+5-->5.1V
+5-->5.1V


Many Thanks once again

Rob.

[sleepydwarf]

Hi all,

Just as an update on this machine I have now managed to track what was causing the strange video issue.
While browsing for schematics and ideas I stumbled across a couple of images of someone having used leaded caps rather than SMT or SMD (may have been BlueBMW, thank you if it was), I decided to give it a try myself as I don't like working with SMT or SMD as the pics probably show.

I borrowed a hot air work station and removed all the caps from the board, hot air was without doubt a much safer way to do this rather than an iron.
Any way with all the caps removed I could get a much better look at what was going on. Long story short, the video issue was caused by a part lifted pad, the positive side of C6 was connected to L1 inductor, but the trace the other side of the pad which connects to the centre pin of Q5 had detached from the trace, once this had been patched the video was displaying as it was before.

There is another cap being C39 which has a lifted pad also, however there is no trace on topside of the board so I am unable to just patch that, I have tried to solder to what was left beneath the pad, it seems secure but I am not 100% sure it is connected. If anyone has access to schematics would you either be willing check for me or post a scan of relevant part please, that would be a great help.

Also this machine is still sadly suffering from its original problem of only briefly flashing the insert disk message briefly. It does this whether the floppy drives are connected or not.

Thanks again to all that have helped so far.

Rob.

[msxtrd]

Just two cents out of my own experience. When the SCSI/FD sub board is disconnected, the XVI compact will not boot several floppy disks. Usually disks which boot into higher versions of human OS.  As far I can see there is also an 1A fuse on this board. It should have blown if something was short circuit? On the back of XVI there should be also a switch to select from which drives to boot (internal or external). I did myself flick it accidently few times and then the disks would not boot at all. I hope you will solve the problems eventually .

[sleepydwarf]

Thanks msxtrd, I hope I sort this machines problems eventually too  . There is a fuse on the daughterboard you mention yes, checked that with multimeter and it does have continuity. The internal drive ID switch is set to 01, though with switch set to alternate position the results are the same.

I have managed to get my hands on a standard compact xvi to aid in tracking the problem with this red zone.

First thing I tried was booting disks that I had written with my usb floppy drive and they worked fine.
Next I started swapping bits from one machine to another. I took from my red zone the scsi/fdd daughterboard, floppy drives, ribbon cable for floppy drives and daughterboard and power supply all worked ok in the standard compact. Nothing used with the red zone made any difference to the symptoms it is suffering from.

Only thing I have noticed is the ribbon cable connectors on the motherboard do not seem to be straight. Have come across some older kit before with weakened plastic from age, one was an Amiga 1500, and the other was an old mediator board from an A1200 tower system. In both cases the PLCC sockets had sort of bowed on all sides. To sort those out I replaced the sockets, PLCC sockets though are really easy to get hold of.

Has anyone else ever had any kind of issues with the connectors?
I guess one solution would be to hard wire, be a bit of a pain to do though.
Could there be a problem with the FDD controller?

Any thoughts or ideas please feel free to shout.

Thanks all,

Rob.

[sleepydwarf]

Hi all,

Thought I would update this thread with progress I have. Well not really progress as such but I have a working Red Zone now at least.
As spare time is pretty rare at the moment I decided to take a slightly different approach just in the interest of making some progress at least.

I decided to transplant motherboard/mainboard from standard compact into Red Zone, I removed the clock mod board from the red zone board and fitted it to the compact board.

The machine now works great at 10,16 and 24 Mhz. I have read a few posts here and there asking about whether this was possible, well I can confirm it is. I can also confirm that an I.O Data SH-6BE 4Mb RAM expansion also works fine at all speeds.

I don't seem to be able to find any benchmark software as such, but if I load Tetris and leave it running its rolling demo, then switch from 16 to 24 Mhz it is possible to both see and hear the speed difference.

I have not given up on the other board, just put on a shelf for now until more time is available for it. I am convinced from my side by side comparisons with a multimeter that the fault is within the video circuitry.

Lydux in case you happen to read this, the last voltage measurement you asked me to carry out is still low even tho the blurred image is now resolved, would you agree with my guess that the fault lies in the video circuitry somewhere?

Last time I did side by side comparisons with both boards running I traced the point you asked me to test to a point on the underside of the board, sadly I cant remember where exactly but traced it further back to the RM28 which I think is a resistor bank, or resistor pack. comparison between the two boards show that one or two points on that resistor bank were considerably lower on the faulty board than the working one.

Any way I wont drone on about it but will re visit it when I have more time on my hands.

Many thanks to all that have offered help and ideas, always greatly appreciated, even now  , thanks all

[H68k]

So you can flip the switch between 16 and 24Mhz mode's with impunity while the machine is running? if so.. that is quite interesting. I read X68ks with over clock mod's have the same issue Mega drives with OC mods do, attempting to change the clock speed while there running will make them hang or in the X68ks case, hang or throw an error.

Having had a look at the data sheet of the 68k QFP processor that's in the compact models, it states 20Mhz is there highest clock speed.. so I guess these things truly are in the "red" zone..


Would you mind taking some pictures of the over clock mod board if it's not to much trouble sleepydwarf? I'd like to see the hardware hack that makes them "hot rods" up close with more detail than the pictures I can find already.

[sleepydwarf]

Hi H68K,

I wouldn't say it is problem free switching while running, it does take strong objection to being switched a few times as I found out while comparing the differences. So far though, every time I have just switched from 16 to 24 it does it without a problem.

The machine does generate some warmth in 24Mhz mode tho, not drastic but noticeable, enough for me to consider a cooling mod or maybe I am just a little over concerned.

No problem on the pictures, will try take some later on today, it is all back together at the moment for the first time since it arrived or I would have upped them now. I do remember there is not a huge amount to the mod. A crystal, one IC and a CAP or two, then just the wires to connect to the board and the switch, and a trace cut on the underside of the board between the crystals.

Will try take shots later today.

[sleepydwarf]

Here is a pic of the Red Zone clock mod. Sorry is not the best image for detail, combination of my unsteady hand, poor lighting and camera phone.
The crystal is a Toyocom 48Mhz, and the IC is a 74ALS157AN

[H68k]

Thanks for going to all the trouble of taking it apart, sleepydwarf.

It seams the over clock mod board is not that dismisser to the ones other people have made for there own OC mods.

now that you mention a cut trace on the motherboard.. I'm not that sure about attempting to knock up something smiler my self.. the compact model's motherboards are delicate compared to the ones in the tower models (both boards from my dead XVI tower felt quite sturdy in comparison) and it's stupidly easy to break traces on them, from what I've been told.


If your worried about the heat from the 68k, you could try some combined aestivate/thermal compound and affix a heat sinc. but be warned: once it sets, you will not be able to easily remove it.. not without damaging the plastic around the chip in some way.

another problem is the clearance between the top side of the motherboard and the plastic chassis.. there's only a few millimetres of clearance between them.. so I don't really know where you could get a heat sink from that's short enough to fit. one's for laptop chip sets maybe?

[RetroFixer101]

Hi all,

Just as an update on this machine I have now managed to track what was causing the strange video issue.
While browsing for schematics and ideas I stumbled across a couple of images of someone having used leaded caps rather than SMT or SMD (may have been BlueBMW, thank you if it was), I decided to give it a try myself as I don't like working with SMT or SMD as the pics probably show.

I borrowed a hot air work station and removed all the caps from the board, hot air was without doubt a much safer way to do this rather than an iron.
Any way with all the caps removed I could get a much better look at what was going on. Long story short, the video issue was caused by a part lifted pad, the positive side of C6 was connected to L1 inductor, but the trace the other side of the pad which connects to the centre pin of Q5 had detached from the trace, once this had been patched the video was displaying as it was before.

There is another cap being C39 which has a lifted pad also, however there is no trace on topside of the board so I am unable to just patch that, I have tried to solder to what was left beneath the pad, it seems secure but I am not 100% sure it is connected. If anyone has access to schematics would you either be willing check for me or post a scan of relevant part please, that would be a great help.

Also this machine is still sadly suffering from its original problem of only briefly flashing the insert disk message briefly. It does this whether the floppy drives are connected or not.

Thanks again to all that have helped so far.

Rob.

I'd just like to say a BIG thank you to sleepydwarf for posting this article and his fix as I had exactly the same problem with a blurred display on my Compact Redzone that I recently bid for on Japans yahoo auction and won. I completely recapped all parts inc mainboard but the original blurred image fault remained. The board also had corrosion on it in several places from leaked capacitors as was expected. I originally thought my fault was related to the 74ALS04 RGB chip on the underside of the board as the levels were really low especially as I had to turn all three RGB potentiometers on the underside near the Display connector right to their maximum to even get a viewable image on the screen that was very blurred.

I read this post checked the Capacitor C6 and inductor L1 that you mentioned to find L1 open circuit as it must of rotted away with the corrosion from the leaked capacitors near by. As I didn't have a replacement inductor I made a very very crude twisted wire quick bodge Inductor to see if it even worked and OMG a crystal clear and very bright image appeared before me eyes!!

You've probably saved my days if not months of trying to find the issue. I've just got to order a replacement component now especially as I have a Midiori MIDI card and the SCSI adaptor to connect my BlueSCSI to the compact inbound from abroad.

I'm so thankful for your post on this excellent forum so keep up the good work resurrecting these very special computers.

[sleepydwarf]

That is excellent news. I am so glad this helped you bring another hard to get hold of machine back to life. That is after all the idea of forums like this. Hope for help if needed and some time later it sheds some light on someone else's problem.

Thankfully my botched together red zone is still going strong, sadly these days I have even less free time so my original red zone board is still awaiting attention.

But once again happy this helped at least one person, hope you have great fun with your red zone.

[RetroFixer101]

That is excellent news. I am so glad this helped you bring another hard to get hold of machine back to life. That is after all the idea of forums like this. Hope for help if needed and some time later it sheds some light on someone else's problem.

Thankfully my botched together red zone is still going strong, sadly these days I have even less free time so my original red zone board is still awaiting attention.

But once again happy this helped at least one person, hope you have great fun with your red zone.

Thanks Sleepydwarf I think i've got the bug now as I imported a very tired and badly modded faulty XVI that I had to repair as it had no XTAL crystals present as I think they must of been harvested for another project or to sell. It was also very rusty and casework was very badly damaged.

After a full recap inc psu rebuild and also hunting down several modern alternative crystals and fdd refurbishment (not for the faint hearted) it's all up and running again but I'm a bit disappointed as it's still the stock 2mb so it will not run most games so I just need the correct memory upgrade and another cheap MIDI card.

I am looking for an x68030 to complete my collection but they are so expensive and the Xellent30 that are listed at present are not worth the money they are listed at so i will just have to keep looking but want to scratch that itch as there's nothing like when you've done a full recap including psu rebuild and it works!!

Thanks again