Trs-80 In My Hands! Yay!

[Theory5]

Thanks, i forgot about those knobs, they are on the underside of the model 3 right across from the power I think.

[Theory5]

VISUAL!

yea I can see it but now I have a differnt problem, you know when you get bad reception on your TV and the picture is moving down very fast ( i think that is called scrolling or rolling or somthing like that)? that is what is happening.is it the connection? or somthing else. pressing break didnt work.

[CraigD]

VISUAL!

Yay!

yea I can see it but now I have a differnt problem, you know when you get bad reception on your TV and the picture is moving down very fast ( i think that is called scrolling or rolling or somthing like that)? that is what is happening.is it the connection?

Sounds like horizontal and/or vertical hold (“h-hold” or “v-hold”). From you description, v-hold. There should be a knob for each of these. These usually don’t need frequent adjustment, but may have gotten moved around when this box was wherever it's been for the past couple of decades. See if you can find them, and play with them until the picture holds still.

 

A bad connection would look like “snow” or static”, so I don’t think this is your problem.

[Theory5]

what would the knobs look like? are they on the outside?

I looked and there are no outside knobs for adjusting that.

[CraigD]

what would the knobs look like? are they on the outside?

I looked and there are no outside knobs for adjusting that.

I believe they were on the back of the Model I’s monitor. I’ve never actually seen a Model III, so don’t know where they are on it. If they’re not on the outside, hopefully they’re someplace pretty easy to get at without any major disassembly. They may be labeled with something like “vert”, or “v-hold”.

 

Worst case (other than they don’t exist at all), they’re little screwdriver-adjustable “trim pots” on the edge of a board somewhere inside the monitor part of the box. Unless you’re expert with TV’s, DON’T mess with anything in there – CRTs can have some parts capable of delivering a lethal shock, even when they’ve been disconnected for some time from their power source.

 

There are a number of sites with images of the original manuals, such as this one – though this one is very slow – looks like about 30 min to download a 5MB .zip file. It might help.

[Theory5]

oh yea that link never works, I download the thing but it only has one page that says somthing about not downloading to much at once and only on weekends and such.

yea I know about CRT's, I stay away from anything taht looks like it holds electricity, and I will have my dad help me, or I will wear rubber gloves I use for playing with stuff (mostly playing with electronics that can do stuff, but as a general rule I don't mess around with things that have to be plugged into an outlet. what is a trim pot? does it look like a small round thing that is standing up? like some sort of ferris wheel if you have enough imagination. or is it one of those little boxes that have a little adjustible thing that you adjust with a screw driver? I will look

cause there are some of the ferris wheel ones in the circuits near the CPU.

[CraigD]

I checked the manual’s index, and it has entries only for brightness and contrast adjustments – no mention of a v or h hold. I’m out of ideas – I fear this is a job for an electronics troubleshooter, and possible not fixable without spare parts. There appears to be no easy way to use an external monitor.

 

I’d high hopes of this machine running again, but it’s not looking good

what is a trim pot? does it look like a small round thing that is standing up? like some sort of ferris wheel if you have enough imagination. or is it one of those little boxes that have a little adjustible thing that you adjust with a screw driver? I will look

cause there are some of the ferris wheel ones in the circuits near the CPU.

Here is a picture of some trim pots. Trim pots – short for “trimming potentiometers” – move smoothly – if it moves in clicks, it’s some form of switch, and not what you’re looking for.

[Janus]

Okay, according to this technical manual:

 

http://www.1000bit.it/support/manuali/trs/Model%20III%20Technical%20Reference%20Manual%20%281981%29%28Tandy%29%28pdf%29.pdf

 

The vertical hold is found on the video board and is R612. (it's near the edge of the board.)

 

You'll have to adjust it with the power on, so it is best to use a plastic tool to make the adjustment.

[alexander]

See, i have a problem with this though:

This month has been awsome, I got vista

that, right there is one heck of an oxymoron...

[CraigD]

See, i have a problem with this though:

This month has been awsome, I got vista

that, right there is one heck of an oxymoron...

Fear not, resident microsoftophobe/clast – it’s a near certainty no TRS-80 will ever sully its 4 to 48K of memory with anything having to do with Vista :hihi:

[Theory5]

well, ive got the bars to stop scrolling but they still arnt displaying anything.

my dad says if it had anything to display we would have seen it even when it was scrolling(or rolling)

[Janus]

In case you have trouble downloading the manual, here's an image showing where the video board is located and the approx. location of the vert-hold adjustment. (the circle on the video board.)

 

 

If adjusting the vertical hold doesn't help, there may be a problem with the video sync portion of the main logic board.

[Theory5]

we got it to hold, but how would we figure out the problem? there is no text.

 

you guys want to continue this in the chat system? I hate talking to people through forums if you can use the chat system.

[Janus]

we got it to hold, but how would we figure out the problem? there is no text.

 

you guys want to continue this in the chat system? I hate talking to people through forums if you can use the chat system.

 

Are you sure all the connections from the main board to the video montitor board are hooked up and tight?

 

Other than that, it looks like a signal tracing job, and you need an o-scope (and the knowledge needed to use one) for that. There may be a bad component in the video circuit.

[Theory5]

I thought all the connections are tight but I will go check.

O-scope? my dad might have one.

 

all the connections are tight

[Janus]

O-scope?

An oscilloscope:

 

[CraigD]

It sounds as if you’ve gotten the display adjusted OK. I’m suspicious again that you need to do something special with the keys to get the machine started.

 

The operations manual says to power on (or press the orange RESET button) while holding down the BREAK key in order to start the machine if it has disk drives & controllers installed. It doesn't say what will happen if you don't, but maybe that's what's happening to you.

 

You should get a “Cass?” prompt, then a “Memory Size?” prompt. Pressing ENTER at both should get you to the

READY

>

prompt, from where all should be well.