Re: Office System .DC42 images?

From: Jason Perkins <perkins.jason_at_email.domain.hidden>
Date: Mon, 13 Nov 2017 14:17:40 -0500


My 2/5 and 2/10 both had a high voltage warning sticker on the original tube, that might be one way to tell if it's been replaced. Another way to tell is to look at the date. On the original CRTs there's a sticker near the top middle of the tube with the year and week it was produced.

The video board voltage regulator failed on my 2/10 shortly after I got working. I did notice the raster was smaller than the burnt in on the CRT, so perhaps something is dragging the B+ down? I do know the new regulator I installed gets super hot. I also lifted one of the traces off the board when replacing it, they seem to be very delicate.

The video on my 2/5 is so stable I'm reluctant to even break the factory glue on the trim pots!

-J

On Mon, Nov 13, 2017 at 1:58 PM, Tom Stepleton <stepleton_at_email.domain.hidden> wrote:

> My Lisa 1 and Lisa 2/10 have CRTs with different phosphors. The 2/10 has
> the green afterglow that seems typical of P7. The 1 has something that
> seems much more like a classic Mac, albeit not quite the same as my old
> Classic I don't think. It might be P4; it's definitely no P7.
> Unfortunately, I can't lift the covers and check right now.
>
> (Maybe the difference between Lisa and Classic video isn't just in the
> phosphor, too, so maybe it is P4.)
>
> When I recapped/retrimpotted the 1's video card, I noticed that it had
> undergone a bit of treatment from some anonymous Mr./Ms. Fix-It at some
> point---in particular, someone had gouged deep scratches between the pads
> for the FET or regulator or whatever it is down at the bottom of the board.
> Not sure why---perhaps they had replaced that component sloppily and then
> had to salvage their bad soldering job.
>
> In any case, this person may also have swapped the tube at some point, for
> all I know.
>
> My 2/10's tube has the faint imprint of a Mac menu bar, reflecting its
> long service in the front office of my high school some 25-odd years ago. I
> consider it part of the machine's story and patina and don't intend to
> change it :-)
>
> --Tom
>
> On 13 Nov 2017 18:42, "Jason Perkins" <perkins.jason_at_email.domain.hidden> wrote:
>
> I was just reading the Lisa Hardware manual from 1982, and it mentions
> that the CRT is a P4 phosphor. So I suppose this is more like the designers
> intended?
> I wonder when the switch to P7 happened.
>
> ~10 years ago I got a NOS Lisa spare CRT, and the date on the tube is from
> 1978! I wonder if they just pulled whatever the tube maker had on the
> shelf?
>
> With NOS CRTs being available so cheaply, I'd be hard pressed to go
> through the work of installing a used one with unknown hours on it. But the
> point remains: 12" B&W CRTs are still readily available either new, or from
> other equipment. If your CRT is tired keep your eyes open for a
> replacement. In my opinion having a fresh, crisp crt makes the system much
> nicer to use.
>
> Thanks,
>
> -J
>
> On Mon, Nov 13, 2017 at 1:23 PM, PSchaefer <dr.p.schaefer_at_email.domain.hidden> wrote:
>
>> Am Sonntag, 12. November 2017 18:00:47 UTC+1 schrieb compu_85:
>>>
>>>
>>> Re: CRT. The wonderful world of FleeBay. Most 12" mono CRTs are
>>> electrically compatible. I did some looking for "12" CRT" and came up with
>>> some good results...
>>>
>>
>> Goldstar (LG) 310KAB4K is an excellent choice. It is sitting inside the
>> Atari SM124 display unit, which can be bought for less than $10.
>>
>> Green or amber CRTs would also work. Many years ago I had to fix a Mac128
>> with broken CRT, and the only spare available that day was a green CRT from
>> a cash register. It worked, and the owner liked it. I don't know what
>> happened to this machine and if he ever got a paperwhite tube for it.
>>
>>
>> Patrick
>>
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>
>
>
> --
> Jason Perkins
> 313 355 0085 <(313)%20355-0085>
>
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-- 
Jason Perkins
313 355 0085

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Received on 2017-11-13 14:18:47

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