Conference hydra::amiga_v1

    
    The problems with the A500 fall into two categories...
    
    1)  Marginal power supplies
    
    2)  Chips loosening up in sockets causing intermittent flakiness
    
    Problem 1 has been addressed.  Early A500s had a power supply mortality
    rate of almost 40%.  There is now a new supply that, while adequate,
    certainly has little or no margin for added hardware, such as extra
    RAM.
    
    Problem 2 was also a problem on the ST, the solution to which became
    known as the 'three inch drop' which would reseat loose chips. 
    Atari now holds their custom chips in with small spring clips.  I
    don't think CBM has such a solution, but I may be wrong.  Many problems
    can be solved by reseating the custom chips.
    
    I think any integral-keyboard computer takes a much more severe
    beating than a remote keyboard design.
                                                
    Eds.

    Re .1:
    
>   The problems with the A500 fall into two categories...
>   
>   1)  Marginal power supplies
    
    This is hardly news to anyone who ever owned a C=64.  Commodore has a
    history of trying to save pennies on power supplies.  They assume that
    a relatively small fraction of their buyers will attach cartridges and
    the like which might overload same.  That's why a brisk business in
    after-market C=64 power supplies has emerged (and why the C=1764 RAM
    Expansion Unit comes with a heavier power supply).  Commodore's
    assumption might have been accurate on the C=64, but I suspect that the
    ill will engendered by this approach has been more costly than
    providing adequate power supplies in the first place.
    
>   2)  Chips loosening up in sockets causing intermittent flakiness
    
    FWIW, the C=128 has tabs which press down on the socketed chips from
    the EMI shield.  I thought they'd been provided as a heat sink, but I
    guess they're actually mechanical hold-downs.  Perhaps the A500 has
    such tabs and the owner could simply bend them so they provide more
    pressure. 
                                                         

    When I had my A500 into Five-D for repair, I overheard the owner ask 
    one of the techs whether I had a "heavy" power supply.  Presumably a 
    heavier power supply means a larger transformer and more capacity, 
    but I don't know whether that means Commodore has switched to a 
    better power supply or that some machines just randomly get a bigger 
    transformer.

    Btw, the problem was a bad custom chip that cost about $100 to fix. I
    also had a problem the first day I had the A500 that may have been
    power supply related.  Omnitek simply replaced the whole machine.  
    Other than that, my A500 has been running an average of three hours a 
    day for a year with no problem.  I wish I could say the same thing 
    about my van.

    - Cliff

    The "heavy" power supply was the one with the problems.
    The overweight transformer put undue stress on the P/S circuit board.
    My 500 came with a "heavy" supply and the supply was DOA.
    The replacement supply was lightweight and transformerless.
    
    I've had no problems in over a year and a half.
    

    Just how heavy was the heavy one.  How do I know which one I have.
    
    Steve O

>    Just how heavy was the heavy one.  How do I know which one I have.

Well, it weighed more than the light one :-)

Only trouble  I've had with my A500 is:

	1. Serial Port died (twice, once on recieve, NOW on transmit)
	2. That blasted GURU :-)



John (The mad hot-swapper  (see 1. above) )

    
    Re: .6

    I have an A500, which, until last night had an (intermittent) problem
    with the serial port.
    
    My serial port died on transmit only. It was constantly sending a
    constant high (+12V) signal on all the RS-232 transmit lines from
    the 1488 transmitter chip. After a bit of poking around, I found
    that this was caused by the fact that there was no -12V supply reaching
    pin 1 of the 1488 transmitter chip.
    
    It turns out that this was caused by a fault in the power supply!
    Where the cable exits the supply to go to the computer, the -12V
    line was shorting against the cable shielding. This seemed to be
    due to a break in the insulation around the -12V wire, cause unknown,
    but probably a fault from manufacture.
    
    The -12V power doesn't get used for much apart from driving this
    chip, so your computer would appear to function normally until you
    try and use the serial port.
        
    So, the fix cost me about 1 inch of insulation tape and a couple
    of hours of time. Maybe you have the same problem.
    
    Hope this is of some help
    
    Stephen

re .7 :

	It certainly does help. It may just save me time when I get up the
courage to poke a soldering iron around Amy again...

My first problem with recieve turned out to be a bad 1489 chip. It wasn't
putting out the proper TTL level to Paula (?) on the RX DATA line.

What, I wasn't nervous unsoldering that sucker and soldering another in?

All in all, it cost about $2.00 at Radio Shack and 3 - 4 hours
to track it down (try that with a logic probe and DVM!)

John

    I have used one of my A500's as a test bed for multiple products.
    One situation that could be considered a "reliability" problem is
    the marginal system clock in the A500.  The clock, which can be
    seen on pin 15 of the 68000, has a component silk screened on the
    line as R-103.  In place of this mysterious R-103 is a 100pf cap.
    
    From talking to several after market manufacturers, the consensus
    is that the cap was put there to make FCC emissions standards. 
    The rise time and amplitude of the clock is affected.  Removing
    this cap (actually cutting one lead) cleans up the pulse, increases
    amplitude from 3.2v to 3.8v, and now combinations of hardware that
    were once flakey are now rock solid.  Particularly the combination
    of a 2000-style C-Ltd disk controller and a Micron 2meg expansion.
    Prior to cutting the cap out, I couldn't even get this combination
    to boot without seeing the guru.  Using this combination with an
    accelerator board wouldnt fly at all.
    
    For those of you expanding your A500, I would recommend this
    modification.
    
    John
    

    Bought my 500 in June '88.  Had it 3 days when programs began acting
    screwy.  Store tech thought it was the infamous Angus chip seating
    problem but re-seating the chip didn't fix it.  They gave me a new
    computer and it hasn't burped even once since.
    

    An addendum to .10.  The 500 failed after running Jet for 7 hours
    straight.  When I got the new one home, I let Interceptor run 4
    days in demo mode to weed out any DOA's.
    

    my amiga came down when I bought a ProDrive.  The store swapped
    every chip in the board before swapping the ProDrive and fixing
    the problem.  DF1 once came down when I built my own printer cable,
    but it returned when I clipped parallel port pin 16, so that the
    printer was no longer sinking  ioINIT.  Oh yeah, the first day I
    got the 500, it wouldn't boot.  I just kept trying to boot until
    it booted, then I made a copy of Workbench, and sent it to CBM for
    a replacement (per coupon included with computer). 
    Tom

    I've only had mine a couple of three or four months, but I've never
    had a bit of trouble with it.  
    
    Just thought I'd put in a 'good' report, after reading so many replies
    about problems.  
    
    Maybe the reason you see a number of problem reports is that so
    many A500s have been sold?  Maybe?  <8-}
    
    					John

    Ditto .13
    
    My little darling is a year old now and she's been great! 

    And another, 10 months and not a hiccough.
    					Alan T.

    Mine's four (going on five) months old, works flawlessly, and has seen a lot
    of movement between work and home.

    I've had my 500 for about 10 months. Just recently my power supply
    went bad (it is the new type). I took it to the local authorized
    repair center for repair. It was supposed to take 5 days but after
    10 days of them telling me they're still working on it, I decided
    to fix it myself. I figured they had just been telling me they were
    working on it and hadn't really got to it yet. But when I got it
    back I saw they had tried replacing all the transistors. Anyway
    it had a lot of ripple on the +5V so I replaced 3 3300uF filter
    caps in the 5V circuit and it worked fine.(I think only 2 were bad
    but my soldering iron was already hot). About 3 days after the power
    supply was repaired I started getting a grren screen on power up
    (ram fails selftest). I reseated the custom chips and that fixed
    it.
    I've had some flakiness in the past. I've got the microbotics expansion
    ram and an external ProDrive and I think the power supply just can't
    handle it. So I ordered the Phoenix CPS500 from ComputAbility ($75).
    It just arrived yesterday. Now there's a power supply. +5V @ 8A,
    +12V @ 1.25A, -12V @ 0.5A, metal case, 3 spike protected AC outlets.
    
    tom

    
    What's really distressing about these A500 failure reports is that
    in each case mentioned here, the USER implemented his own repairs.
    Now, there's a good level of technical competence in this group,
    but what's the average schmuck to do with a marginal supply that
    ain't quite broke but ain't quite right?  Especially when repair
    shops take weeks to months to repair problems?
       
    If Commodore wants to be taken seriously as a volume supplier of
    high-end personal computers, they'd better get their act together
    on why these machines break in the first place and how a consumer
    can get them repaired in a reasonable amount of time.  If this involves
    beating some dealers/repair shops about the face and neck, then
    so be it.
    
    Frankly, I'm surprised at the number of problems in just this small
    sampling of people.  I hope these were birthing pains and not
    indicitive of cost-cutting-to-death on the A500.
    
    Thankfully, my A2000 has been rock solid, as was my A1000 for 2.5
    years.
    
    Ed.

    I have had my amiga 500 for 3 weeks.  I have not had trouble with
    the computer,it is the workbench and basic disk. When I load the
    workbench disk it puts me in CLI.  What am I missing???
    
        M.A.H
    

    df0:s/startup-sequence
    has to load workbench 
    load wb
    and something else.
    I think it's probably OK for anybody to copy their disk to you.
    Tom

One thing I'm noticing here is the service centers methods.

 "... they replaced every chip until they finally figured out the PRODRIVE was
      bad... "

 "... Looks like they tried to replace all the transistors..."


Come on, are these people competant or are they just good with a soldering
iron?  Any average shmuck (good one, Ed!) can replace things till it works.

Do these poeple [service centers] *troubleshoot*?

I'm not trying to offend anyone, just seems like the Computer Store
level service is a bit on the weak side. If these people cannot perform
quality, professional repair, then they shouldn't be collecting the cash
for it.

John

    re .20
    
    actually, the commands are:
    
    s:startup-sequence.....
    .
    .
    .
    loadwb
    endcli
    
    
    But I'm sure you'll get the hang of things soon with all the help
    around this place....scott  (killing time before he goes)
    

    What is it with C= and power supplies?  My almost 2 month old 2000
    is in the shop after popping a power supply.  (At least that's what
    it looked like to this untrained eye.)  No smoke, no fire, but also
    no power.
    
    Almost makes me wish I'd hung onto my 2.5 year old 1000. 
    
    On the up side, though, I wouldn't trade my Amiga for anything.
    I've become very attached to it, warts and all.  It's beauty and
    utility outshines its problems.
    
    
    Gary

Taken from USENET (without any permission):


Newsgroups: comp.sys.amiga,comp.sys.amiga.tech
Path: decwrl!ucbvax!hplabs!hp-sdd!ncr-sd!crash!stuff
Subject: drive
Posted: 13 Oct 88 20:14:22 GMT
Organization: Crash TS, San Diego, CA
Xref: decwrl comp.sys.amiga:26161 comp.sys.amiga.tech:2716
 
I've had an amiga 500 for 11 weeks now.  The last 7 of which it's been in
the shop for drive problems.  Ever week or so, it comes back supposedly
fixed.  Ever week or so, I take it back to get it fixed.  Now the dealer
I bought it from tells me I need a new drive, but they won't cover it
under the warranty.  No way am I going to buy another garbage drive from
Commodore for $170.00.  Has anyone replaced their internal drive with a
generic 3 1/4 inch drive from say Toshiba or Sony?  Or is there something
special about the drive Commodore uses?
 
David Yip
[email protected]
[email protected]

I finally fixed my serial port (again!).  It was the 1488 (RS232 driver chip) -
$1.29 at Radio Shack.

I'm sure this was my own doing - swapping cables etc..

JOhn (who will now head the WARNING on the back of his Amiga!)

On the topic of A500 power supplies...

    My  solution  was  to purchase a baby AT case and use it's power!
Lots (200W) of power. It also provides a place to put hard disks  and
a  5.25"  floppy  with  ID  circuit  I cobbled together with a little
wirewrapping. The monitor outlet controls my 1084 monitor power  with
a little $5 adapter widget.

    This  has worked wonderfully for the A500. Flakiness is all gone,
though there were a number of other problems on the way to a reliable
A500. I think my A500 skipped  Commodore's  (albeit  skimpy)  quality
control folks.

    If  you  are considering trying this (less $ than a Phoenix power
supply) then good luck finding a source  of  the  square  DIN  plugs.
Commodore  will  only  sell the whole power supplies. I got mine from
Five-D off a dead A500 supply they had in the parts box.

	-SES

	Thanks for the response. I decided that it would certainly
	be better to stick with a local dealer rather than shopping
	around for the cheapest available system. That way I can
	take it back easily if there ARE any problems.

	I admit I did have a second look at the ST, but seeing the
	two machines together in the store made up my mind.

	FWIW, my VAX station power supply went away after only 2
	weeks. The field service guy who came to fix it said that
	he would have to order a replacement because they had run
	out - they had had so many others go recently. That was
	last Monday ... :-) :-) :-)
	

    	My A500 has been running fine for about a year now. It has been
    through lots of use/abuse and still runns fine. My 3 kids beat the
    H*ll out of it running games from time to time  and they haven't
    even broken a key. Power supplies are a problem in most systems
    even DEC systems have power supply problems. The good part is that
    the power unit is a small box which any fool should be able to swap
   . Fixing the unit is fine but a todays labor costs it probably doesn't
    make sence to fix it unless you do it your self. Another thing being
    a seperate unit it doesn't cause heat problems in everything else
    like on many other PC systems.
    Jeff Filer
     

    
    just remember "built to a price" or "power without the price".
    Same rules apply for the Amiga 500 or the Atari 520/1040.  To
    save money, they try to cost reduce as much as possible.  Sometimes
    they go too far, or get a bad supplier, etc.
    
    You have to look beyond things like dead power supplies, to what
    quality was built into the basic design.  Yeah, right, that's the
    ticket... read the Jay Miner Byte article about the design of
    the Amiga.
    
    -Dave

Re: .23

If it's any consolation, your only the second Amiga 2000 owner I've heard
of with power supply problems.  (The first was last week on Usenet.)

A lot of the griping about the 500's power supply is from people who
smoked it by adding too much expansion hardware.  This is pretty easy
to do given how close that power supply is matched to the system.  The
2000 doesn't have that problem with its 200 watt power supply.

I've had my 2000 for a year now.  Zero problems encountered.

Three weeks ago I did the leg work to upgrade a friend of mine from
a 1000 to a 2000 (he is recovering from a stroke, and needed someone
to pick the system up for him).  I tested his machine out, and I noticed
that the new 2000 is much quieter than my year-old 2000.  The power
supply was of a different design.  His machine was from Taiwan; mine's
from Germany.

    Re .30:
    
   Actually, Randy, I think I'm the first and only 2000 owner you've heard
   of with power supply problems.  It was I who talked about my 2000 on Usenet
   last week.  I got some email from Randall Jessup of C= who said that
   he's only heard of one bad 2000 PS.   Guess I'm just one of the lucky
   ones.
    
    Re quiet PS:
    
   Gosh, if my new Taiwanese 2000 is quieter than your W. German model,
   you must have to wear earplugs. :-)
   
    
    Waiting as patiently as possible for the return of my Ami,
    Gary

    I've had by B2000 for 13 months, and my only problem is a fast clock.
    I used to turn it off after using it.  Now that I have to compete
    with Wife and Daughter for computer time, it stays on all the time.
    I don't find the fan noise objectionable, though it is noticable.
        John Sauter

    re .32
    
    Somewhere around here, there's a not on calibrating your clock.
    Try to find that, and you won't have any more problems with it being
    too fast.
    
     - Chris
    

    I have tried the calibration program.  I can't screw it down any
    slower than .3% fast (602 ticks in the time of 600).
        John Sauter

    re .34
    
    You might have to either buy a new variable capacitor, or add a
    small one to the circuit.  This would require soldering, which I'm
    sure you aren't enthused about.
    
     - Chris
    

    re: .35--You're right, I'm not enthused about soldering the motherboard
    of my Amiga.  My hardware skills aren't very great, and I depend
    on that computer!  I wonder if the new Amiga store in Merrimack
    is "hungry" enough to try to fix the problem.
        John Sauter

    re .36
    Hmmm.  I don't know.  I'm down here in South Carolina, but I don't
    think it would hurt to go ask them.  They may give you a special
    deal.  It really shouldn't cost much.  Just make sure they do the
    job right the first time.
    
     - Chris
    
    

    I bought my AMIGA 500 last November (1987). I originally had problems
    right out of the box and had it replaced. Since then the replacment
    a500 has been moved around quite a bit from the upstairs to the
    basement. (I have a small house...) and the system has run great.
    
     All-in-all i wouldn't trade it except for maybe a 2000!

    In an article in "BCS Update" on sick computers, a service manager 
    for a place in Framingham that repairs all brands says that power 
    supplies failures are his most common problem.  RAMs and disk drives 
    come next, followed by keyboards.  His recommendations are to get a 
    surge protector and a keyboard cover.  Also, if you've got a hard 
    disk, let it run, and if you shut it down, park the heads.

    - Z

    I have had my A500 for 10 month with four problems.  The first when
    it was about two month old Feat Agnus was loose.  The second was
    about two month ago I turned it on and the screen stayed yellow.
     Tearing it apart and turning power on I pressed each socketed chip
    until I touched gary the Hand with the disk apeared all was well.
    I had an inermitant problem with the power supply dying this was
    a problem I induced on my own.  To make sure my C.Ltd controller
    did not come loose I placed a couple of plastic tye raps around
    the metal RF shield and 86pin connector.  This deformed the shield
    slightly and it was reaching out and touching a etch between the
    top of the 86 pin connector and the bottom of Denise.  Now when  I
    first turn my system on after sitting eight hours or so I get a
    not a dos disk when I try to mount my hard disk.  Turning the system
    off then back on correct the problem every time.  This I feel sure
    is the Seagate disk itsself.  (I added a 238 Watt power supply with
    my hard disk upgrade).  Other than AmigaBASIC being its normal flakey
    self and some guru's I have chocked up to P.D. software no troubles.
    
    I almost forgot one other.  After moving my Amiga into another room
    it started hanging when I moved the mouse across the mouse pad. This
    was very intermitant and ended up being a loose ground screw on
    the outlet of the power strip I had every thing plugged into.  A
    large soldering iron fixed that.  That ground wire is never coming
    off of that screw.
    
    Out of five problems in 10 month two were Amiga problems the rest
    were external. 
                                                                     
    To add a little perspective here I work for Field Service.  Four
    years ago I remember spending a Saturday squating on the floor ripping
    a customers new 8600 apart and going over each module with a soldering 
    iron a magifying glass and a flashlight looking for bad solder joints.
    I also had to tighten all power connections to the backplane. 
    This turned a very flakey 8600 to a very solid running machine.
    
    Alan  
                                       
     
    

    Last month I had a recurrence of the screen display breakup problem 
    that I had a few months ago.  I took it to D5, and they replaced 
    Denise again.  When I hooked Amy up at home the problem started up 
    again, so I went out and bought a #10 Torx wrench, opened Amy up, and 
    started poking chips.  The problem went away when I jiggled Agnus.  
    Now the machine has been acting flaky about booting when I power it up.  
    Again, if I jiggle Agnus a little the problem goes away.  I've been 
    leaving the RF shield off and the cover unscrewed so I can give Aggie 
    a goose when she needs it.
    
    Agnus seems firmly seated.  A friend suggested that there might be a 
    break in one of the runs that intermittently opens, but I can flex 
    the machine slightly and bounce it with no problem.
    
    Any hints or suggestions from hardware oriented noters would be
    greatly appreciated.  
    
    - Cliff

    	You might want to try actually removing and then reinserting
    all the socketed chips in your A500.  I had screen breakups and
    crashes until I took that step.  I had previously only pushed down
    on the chips, which provided only temporary relief.  Perhaps there
    is a thermal contact problem?  Make note of the Angus orienation
    before removing it and of course use a static mat & wristband. 
    I also cleaned the contacts with an alcohol swab.  
    							Good luck,
    
    							Marty

    I pulled Agnus and cleaned its contacts with an eraser and bent the 
    tabs on the retaining clip so it would exert a little more pressure.  
    So far no problems.  Thanks for the tip!

    - Cliff