[vcf-midatlantic] Repair Workshop

David Gesswein djg at pdp8online.com
Thu Aug 1 21:13:59 EDT 2019

On Thu, Aug 01, 2019 at 01:14:12PM -0400, Douglas Perry via vcf-midatlantic wrote:
> Now that I'm signed up for this months workshop I was hoping to get some
> tips on how to properly prepare (supplies needed, ect..)

Best to bring what you think you will need. Others will bring stuff also
which you normally can borrow if you find you need something you didn't
bring but can't count on it being around.

I propably over do it and try to bring half my basement but I'm 3.5 hours
away so not practical to go home and get something I didn't bring. 

The other would be what you think you may need that you don't have. If
you know you need something you don't have if you ask ahead of time people
frequently can bring it.

The other would be if you will need assistance. Asking ahead you can know
if people with experiance think they will have time to help. Some people
spend a significant amount of time helping others and some mostly work on
what they bring.

> I testing I've done so far is to simply plug it in and turn it on (after
> giving it a week in a temp/humidity controlled room). The PSU and fan came
> to life nicely, the CRT is making a familiar hum but I get nothing on the
> screen not even a blinking cursor. I'm not sure if I should expect an error
> with no disk? I also don't hear any drive noise.(I have no disks)

I have a compaq plus. I had to recap the power supply and had problems with
a pot on the CRT board. Tapping pots can sometimes show the ones that are
flaky. The power supply caps were obviously bad by looking at them.

> >From my research I'm going to go ahead and assume the capacative pads for
> for the keyboard are bad and just order a new set.

I had to replace mine.

> I've searched fairly well and have not found a reputable place to buy a
> 5.25 floppy pre-loaded with MS-DOS 3.3 (which sounds like the best option).
I'm not sure where to buy it. I and a number others could make a disk useable
to boot your machine. My machine has a mismash dos version so may not be ideal.

> So after that ramble here are my questions.
> Is there anything else you all would recommend me bringing?

I like a scope. I always start with checking power supply voltage and ripple
before trying to do more. Normally a couple people bring scopes so you may 
be able to borrow one for a while. I think VCF may have one also. If you 
have spare parts they are good to bring.  My cap stock isn't the best so 
I have gotten them from others when I didn't have correct one.

I would also dig up any available schematics.

Tools needed to disassemble your machine.

> When is the best time show up?

I never make it right at the start so others can answer this.

>It is the Compaq Portable 1.

> Single vertically mounted 5.25 with unused bay and no HDD.

The fun of swapping disks a number of times when you wanted to make a backup

If I make it I can bring my plus which works to use if needed to compare/
verify what the problem is.

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