Re: No Video on Lisa 2/5

Hello all,

I picked up a new BU406 for Q5, and tests on the new part showed expected results. After replacing Q5 and all of the trimpots, this Lisa has video!

https://photos.app.goo.gl/fmi3IcroVgk4Pwql1

This Lisa came with 3A ROMs but no screen kit video adapter, which threw me off initially since the dimensions were way off and there was some noise on the left side. After swapping out the board with one containing F ROMs, everything looks good!

Thanks to everyone who chimed in for the assist.

James

On Wednesday, February 14, 2018 at 12:52:56 PM UTC-5, James Denton wrote:
>
> Hey Tom,
>
> Thought you might be interested to know that CR9 looked OK, but Q5 may be
> problematic. The B<->E readings are near zero in both directions. The B<->C
> readings look OK, however. There is at least one trimpot that needs to be
> replaced (Vertical Hold). I don't have an easy way to test U1, as I don't
> have a bench top power supply.
>
> Will keep you updated as this thing progresses.
>
> James
>
> On Tue, Feb 13, 2018 at 10:55 PM, James Denton <busterswt_at_email.domain.hidden>
> wrote:
>
>> Hi Jason, Tom,
>>
>> Thanks very much for the schematics and the advice. I’m almost done
>> pulling the video card out and will likely wrap that up in the morning.
>> I’ll take a look at Q5 and see if i see similar behavior. I’ll also check
>> out the pots.
>>
>> Will keep you all posted. Thanks again.
>>
>> James
>>
>> On Tue, Feb 13, 2018 at 6:38 PM Tom Stepleton <stepleton_at_email.domain.hidden>
>> wrote:
>>
>>> Sorry---correction, my friend told me to investigate Q5, not Q9. (Which
>>> was fine, although you couldn't tell for sure without desoldering
>>> it---depending on the kind of fault, a broken Q5 and a broken CR9 could
>>> both have produced the reading we were seeing when we were testing CR9 in
>>> circuit.)
>>>
>>> And just in case it wasn't clear---we investigated the diodes and
>>> transistors in circuit but not the *board* in circuit---we had to pull
>>> the board out of the Lisa to get access to anything :-)
>>>
>>> --Tom
>>>
>>>
>>> On Tuesday, February 13, 2018 at 11:20:46 PM UTC, Tom Stepleton wrote:
>>>>
>>>> Worth noting that Bitsavers has an original Apple schematic online as
>>>> well:
>>>>
>>>>
>>>> http://bitsavers.informatik.uni-stuttgart.de/pdf/apple/lisa/hardware/050-4012-E_Video.pdf
>>>>
>>>> The one Jason linked to could be just as good, although I seem to
>>>> remember some revision differences or errors on the one for the Lisa PSU.
>>>>
>>>> Now... just last Saturday I watched a friend---who is very well-versed
>>>> in Apple video systems of that era---diagnose a broken Lisa video board.
>>>>
>>>> For this one too there was no video at all---and curiously, when we
>>>> went to extract the video board to investigate, there was no 'pop!' from
>>>> discharging the anode. Based on these symptoms, my friend told me to put a
>>>> diode tester over all of the diodes on the board (in circuit---not
>>>> extracting anything) as well as on the transistor Q9. Sure enough, CR9 had
>>>> failed closed. Friend concluded that the IN4936 was maybe a bit underrated
>>>> for the job.
>>>>
>>>> As it turned out, we had an analog board from a dead Mac that we could
>>>> cannibalise (the diode it uses in the same role is larger in rating and in
>>>> size), and sure enough, it worked. Maybe someday I'll have the electronics
>>>> skills my friend has, but it'll probably be a while before I do!
>>>>
>>>> My friend supposed that CR9 might be a common failure point for these
>>>> video boards---it would be interesting if you found the problem on your
>>>> board as well.
>>>>
>>>> --Tom
>>>>
>>>> On Tuesday, February 13, 2018 at 12:49:20 PM UTC, compu_85 wrote:
>>>>>
>>>>> I'd start with the video card (after swapping the power supplies
>>>>> around). If you look at the schematic you'll see the width adjustment pot
>>>>> at the top of the board has the 28v output from the regulator on it. Begin
>>>>> there... no B+, no picture.
>>>>>
>>>>> http://www.freeinfosociety.com/electronics/schemview.php?id=1424
>>>>>
>>>>> -J
>>>>>
>>>>> On Mon, Feb 12, 2018 at 11:34 PM, James Denton <bust..._at_email.domain.hidden>
>>>>> wrote:
>>>>>
>>>>>> Hello all,
>>>>>>
>>>>>> I recently picked up a Lisa 2/5 with known memory issues that I
>>>>>> managed to resolve relatively quickly with known-working cards. When I
>>>>>> power up the machine, I hear the beeps that indicate all tests passed and
>>>>>> it's waiting for a boot disk, but there's no video at all on the screen. I
>>>>>> moved the entire card cage to my other chassis and confirmed working video
>>>>>> output there. While I do see some slight mirroring on the left side of the
>>>>>> screen, and the picture seems a little narrower, I believe it may be due to
>>>>>> the 3A ROMs installed on this board.
>>>>>>
>>>>>> Where is a good place to begin troubleshooting the lack of video
>>>>>> output on this Lisa? Should I simply look to recap/rebuild the analog board
>>>>>> or is there something that can be looked at before taking that on?
>>>>>>
>>>>>> Thanks in advance,
>>>>>> James
>>>>>>
>>>>>> --
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>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Jason Perkins
>>>>> 313 355 0085
>>>>>
>>>> --
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