Re: bad bottlecap transistors causing squiggly vectors?

"
I'm starting to wonder if the manufacturing process has changed to the point
where the device has changed specification in some critical way. I can't
see that manufacturers use the same machinery and processes that the did 20+
years ago. A curve tracer could speak volumes as to what is happening
here."

Actually you'd be surprised. I work, and have worked at many Texas
Instruments plants. The equipment they used 30 years ago, is still in use.
Which creates a very interesting problem for me, as I'm the one that has to
repair all the dead boards, and parts on these machines, which have been
obsolete for years. Which is why many Semiconductor plants will often buy
out defunct plants, and move all the machines from that plant to moth ball
storage. So we can rape them for parts. In other cases, we will even make
exact replacement parts to fix equipment.

The newer products built at the new plants are built using newer machines.
Mainly because line widths are now less than 1/4 micron. But even at that,
many of the machines used in Semiconductor mfg. haven't changed much in the
past 30 years. The saying at work goes "Building the Technology of tomorrow,
on yesterdays equipment"

Reasons why they still use old equipment. One it's paid for, so we are
making money. Two the process is already proven so why change it.

On Mon, Aug 30, 2010 at 12:27 AM, PJ <pj1@shaw.ca> wrote:

> ----- Original Message -----
> *From:* Pat Danis <patdanis@verizon.net>
> *To:* vectorlist@vectorlist.org
> *Sent:* Thursday, July 29, 2010 11:54 AM
> *Subject:* Re: VECTOR: bad bottlecap transistors causing squiggly vectors?
>
> Perhaps I should have been more specific. I don't blindly replace
> transistors. If the originals are good, I keep them. (Too expensive) If I
> find a bad one, I do replace them in pairs to make sure the tolerances are
> the same. I don't profess to be an expert in electronics but think that you
> would like to have evenly matched parts. I'm sure one vendors tolerances
> are different from another's. In the description of the wavy lines I
> referred to, it is hard to determine where the problem lies. The specific
> case I am referring to is for a Space Duel monitor I rebuilt. The cabinet
> was a project I purchased as non working. Rebuilt brick, (bad rectifier,
> fuse block bad and hacked wiring), AR board toasted, and monitor
> non-working. After rebuilding the AR and brick and fixing the monitor, I
> could not be sure the if the problem was due to the monitor or the main
> board or something else. I tried another monitor with a jumper harness and
> the "waves" were much less obvious but still there. I don't recall the
> origin of those transistors on the better monitor. I have also found that
> the replacement transistors seem to be less tolerant of Perhaps it could
> have even been classified as jitters. I didn't have time to troubleshoot
> further as I was on a time schedule and had to have it delivered in working
> in a matter of days. I was lucky to get it done as it was due to the hacks
> on the monitor.
>
> I only offered to test a theory I had as a means of contributing to the
> group. I will still attempt to document my findings and then submit them
> here for further abuse/discussion. I would also like to point out that I do
> remove and reinstall the original bottle caps if they are still good but 30+
> years of heat, smoke, dirt and dust do take their toll on the heat sink
> compound and I am doing what I can to keep them running for another 30. Who
> knows, maybe I'm doing something wrong and I'll find it out. As far as
> buying in matched pairs, I don't know if the vendor I purchase from has
> "matched" sets. I only purchase bulk quantities and hope that the
> tolerances are close enough as they came from the same batch. You're right,
> I don't have a curve tracer. Wouldn't know how to use one if I had one.
>
> I still have access to that game and may go by and grab the monitor and
> test it with a different game.
>
> I also recently found a monitor out of a bulk buy with transistor numbers I
> wasn't familiar with. I will dig it out and see what they cross to. I
> would be interested in seeing what somebody else was using to get a monitor
> working. For all I know, they are direct crosses. Just wasn't familiar
> with the part numbers.
>
> Do you have a source for matched transistors at a "reasonable" price?
>
> Pat
>
> Kevin Moore wrote:
>
> I think Generally speaking it's also a good idea to used matched pairs on
> your push pulls too. But since buying MP's are not always convenient, and
> not everyone has a curve tracer to try and match them. I'd have to agree
> with Mark though. I doubt that would be your problem. They would/could cause
> other issues. For example, Walling on Tempest.
>
> Kevin
>
>
> On Thu, Jul 29, 2010 at 10:48 AM, Mark Shostak <shostakmark@gmail.com>wrote:
>
>> Uh, kind of obvious, but you could put the original TO-3 transistors back
>> in, and see if the problem goes away. If you're like many of us, the parts
>> are still on the bench...
>>
>> However, IMHO it's unlikely that it's the transistors causing the issue,
>> assuming you replaced them with the original devices and not subs.
>>
>> Also, rule of thumb in push-pull is to replace _both_ outputs at the same
>> time, and also to replace both drivers when replacing the outputs. This rule
>> primarily pertains to repairs after a failure and not to, "it ain't broke,
>> but I'm fixing it anyway" type activity.
>>
>> -Mark
>>
>>
>>
>> On Thu, Jul 29, 2010 at 10:37 AM, Pat Danis <patdanis@verizon.net> wrote:
>>
>>> I too had noticed that some of my WG 6100s were not as sharp after
>>> replacing all the transistors and doing a complete rebuild of all the
>>> components. The lines were a little wavy and not completely straight. I
>>> suspected that perhaps the bottlecap trannies might be an issue but don't
>>> have the smarts necessary to make a determination if it was the transistors
>>> or something else I might have replaced during the rebuild. I am going to
>>> track my findings in some 6100 rebuilds I will be doing in the next few
>>> weeks to see if there is a correlation to the transistors I am using. I
>>> have 2 different sources for the present time.
>>>
>>> I will see if there is any visible difference between original, and the 2
>>> sets of replacements transistors after a rebuild. My month of August is
>>> pretty booked up right now but I need to get some 6100s done so I will
>>> attempt to get this info posted. I'll even take video if possible. No
>>> guarantees.
>>>
>>> Pat Danis
>>>
>>>
>>> PJ wrote:
>>>
>>> I was looking over Darren Finck's post regarding issues with a G05-802
>>> having amongst a number of things, squiggly vectors. This tweaks my memory
>>> of the issues I had with an Amplifone that had a bad case of twisted
>>> distorted vectors on certain objects (see my starwars posts from last
>>> spring). I also had a similar issue on a G05 with original transistors that
>>> I figured were getting tired, and once replaced, the issue went away.
>>>
>>> The Amplifone in question had new transistor pairs on both channels.
>>> Since the original transistor pairs were long replaced prior to my
>>> involvement with whatever transistor the previous owner had on hand
>>> (literally), I replaced them with the correct parts, and from evidently, the
>>> same batch that I used in the G05.
>>>
>>> What I ended up with was when the drive from the game board was normal,
>>> and the gains on the deflection were set higher to fill the screen, the
>>> vectors were distorted, like the start and stop rates were bad. Tweaking
>>> the drive from the game board to a high level, and dropping the gains on
>>> the deflection board made the effect less evident.
>>>
>>> I'm wondering if the 2N3716s and 2N3792s have changed or the
>>> specifications aren't what they once were. Anyone else seen this?
>>>
>>> ---------------------------------------------------------------------------
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>>
>>
>>
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> ------------------------------
>
>
> I used the exact part numbers (they were fresh stock and came from a well
> known peanut brittle eating beard wearing canuck).
>
> Transistor pairs I have that are found to be wavy on one monitor are not on
> others. Case in point, the ones I pulled from the G05 that were wavy, were
> fine when I was working on a 6100. A 30 year old transistor working as hard
> as the ones in a vector monitor can have all kinds of issues lurking inside:
> heat breakdown, tin whiskers, and more, so replacing them during a rebuild
> in my opinion is cheap insurance.
>
> On the Amplifone I assumed that since the outputs were replaced before, and
> with something that had little substitution value to the originals, that I
> would do all the pre-drivers and the outputs.
>
> What I've learned in the past with RF devices is that sometimes a component
> is made by one person and only one person who knows the secret recipe and
> process (not unlike Kentucky Fried Buzzard) and that without that person,
> the device can't be exactly replicated. I ran into this a while back with a
> GAs-FET, The device was obsoleted because the manufacturer had only one
> employee who made the actual semiconductor materials, and he died.
>
> I'm starting to wonder if the manufacturing process has changed to the
> point where the device has changed specification in some critical way. I
> can't see that manufacturers use the same machinery and processes that the
> did 20+ years ago. A curve tracer could speak volumes as to what is
> happening here.
>
> So many of these monitors are still around, and so many of them eat
> transistors for lunch, I'm surprised that this doesn't crop up more often.
>

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Received on Fri Jul 30 06:35:47 2010