Nice PET but garbage screen

pontus said:

Speaking of the devil:

http://www.tradera.com/Antik_dator_Commodore_CBM_3032-auktion-76668891

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I don't know the values on those, but I think I figured 750 Kroner is pretty cheap for that system.

I remember an IBM PC TX on finn.no that was listed for 5000 Kroner! That's what I call overpriced!

750 SEK was a bargain two years ago. Today it is pretty much the going rate, perhaps a tad on the low side. On the other hand it is the opening bid, so chances are the final bid would be higher than that.

I sold a 3032 + 3040 drive in June for 800 SEK, local pickup. Currently I have a pile of broken drives but not yet any clues how to trouble shoot them other than switching chips at a random.

Of course prices in Norway are a completely different matter than Sweden. Vintage computers tend to cash in 50-100% as much on the Norwegian market, which is why some Swedish sellers have begun to look across the border.

carlsson said:

Of course prices in Norway are a completely different matter than Sweden. Vintage computers tend to cash in 50-100% as much on the Norwegian market, which is why some Swedish sellers have begun to look across the border.

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I know. Commodore 64es goes for about 750-1000 kroner. they're like 100-200 kroner on Ebay.

tezza said:

Hi,
I bought it as a faulty unit, but I'm hoping I can probably work through the problems and eventually fix it. The main problem is this..

Tez

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Hello tezza

I'm new to this group and are wading trough all posts with interrests.
I can tell you that me and my son (14 years old) bought exactly this model with exactly the same problem at an auction last year

.(The auction was at ETA at Chalmers technical university in Gothenburg. There is a very good and funny auction once a year and it will be one this year as well, in two weeks. You nearly allways make a bargain. I f.e. bought a sleve with Telefunken NOS tubes, ECC803S for 100SEK he he he :D at the same auction last year.)

We measured the PSU and different voltages couldn't find anything wrong.

My son read somewhere to try to "exercise" all chips that sat in sockets. He actually did that and... oh what a happy guy he was when the puters welcome screen suddenly appeared. Back from the dead in to a working computer with, as I recall, all the updates to ROM that was available at the time.

This is great fun to see that other people think this old computer is worth to take care of.

I guess I have to comeback with data on ROM's and some pictures as well. Yet another "site" on my allready crowded homepage have to be made

Have you tried the "exercising of the chips in the sockets tezza?
// Ove

Radioman said:

.(The auction was at ETA at Chalmers technical university in Gothenburg. There is a very good and funny auction once a year and it will be one this year as well, in two weeks. You nearly allways make a bargain. I f.e. bought a sleve with Telefunken NOS tubes, ECC803S for 100SEK he he he :D at the same auction last year.)

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Are you going this year? I will be going for the first time, it would be nice to at least say hello to another forum dweller.

ETA in Gothenburg

ETA in Gothenburg

Hi Pontus

Yes I will
We nearly missed it this year because of a vacation travel to Lanzarote. We are back late friday and the auction is on saturday so me and my son are looking forward to this event.
It's not just an auction, it's a happening with very nice and funny people running the auction. Some very special humour to say the least..
:clap2::rofl:

Radioman said:

Have you tried the "exercising of the chips in the sockets tezza?
// Ove

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Unfortunately for me, very few of the chips are in sockets. Almost all expect the large ones are soldered directly onto the board. (bugger!).

I did wriggle the ones that were in sockets but that didn't make a difference.

I've decided as a long-term project, I'll slowly work through replacing chips starting with the RAM first, and socketing the replacements as I go. The alternative is to get a working motherboard, so I'm keeping my eye out for this too.


Tez

I'm keeping my eyes open too. Unfortunately there was no score at all last weekend.

carlsson said:

I'm keeping my eyes open too. Unfortunately there was no score at all last weekend.

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No worries Anders,

Thanks for keeping an eye out for me. Let me know if you find anything. In the meantime I'm going to start working on this board. I'm not going to hurry it. It's going to take me some time to replace and socket all these chips. Hopefully it's RAM but...from my Apple experience I know this fault could be anything.

Tez

My son read somewhere to try to "exercise" all chips that sat in sockets. He actually did that and... oh what a happy guy he was when the puters welcome screen suddenly appeared. Back from the dead in to a working computer with, as I recall, all the updates to ROM that was available at the time.

Click to expand...

yeah i used the same trick when i got rid of my garbled screen problem on the 3032 i got.

Hmm..Ok, I've decided I will NOT replace the ICs on this 3032 motherboard. Rather, I'll look for a new motherboard.

I dragged the MB out of the machine and had a good look at it the other day. While the case, power supply and VDU seem fine, the motherboard is actually in poor condition. About 1/2 the ICS have corroded pins and many of the diodes and resistors also show rust on their legs.

I don't like throwing in the towel, but I think the job is simply too big. Here are some photos...





Chips at the front of the MB (like the RAM) look ok, with no rust as all. I tried the piggyback method but it's didn't reveal anything. Although no mice have been nesting in here, the corrosion at the back of the unit is actually worse than it was in those old APPLE IIs I was gifted. With those machines, there were a number of ICs which were faulty.

Andres is keeping his eye out for a replacement board. It anyone else comes across one, I'd like to know about it.

Tez

3000 series poster

3000 series poster

The 3032 is pretty rare in the USA. I don't think that I would tackle the job either, but if there was a way to immerse the board in a solvent that would clean it, I would try that.

Has anyone seen the Commodore 3000 series poster? There was a cool poster that showed the Commodore 3032 and with tons of info. It was a wall poster for techs and computer programmers and I guess it came with the 3032 when you bought one, or you could get it from the store as a promo.

Bill

tezza said:

Hmm..Ok, I've decided I will NOT replace the ICs on this 3032 motherboard. Rather, I'll look for a new motherboard.

I dragged the MB out of the machine and had a good look at it the other day. While the case, power supply and VDU seem fine, the motherboard is actually in poor condition. About 1/2 the ICS have corroded pins and many of the diodes and resistors also show rust on their legs.

I don't like throwing in the towel, but I think the job is simply too big. Here are some photos...



Chips at the front of the MB (like the RAM) look ok, with no rust as all. I tried the piggyback method but it's didn't reveal anything. Although no mice have been nesting in here, the corrosion at the back of the unit is actually worse than it was in those old APPLE IIs I was gifted. With those machines, there were a number of ICs which were faulty.

Anders is keeping his eye out for a replacement board. It anyone else comes across one, I'd like to know about it.

Tez

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Well, since you have nothing to lose, if you want to know how I fix up boards like that, let me know and I'll let you in on a few tips.

It will take a lot of soldering, but, no un-soldering.

Chances are about 50/50 that you can recover it or, at least, get it to a point where you will be able to discover the actual fault and fix it.

Hello,

I had a similar problem:



After some research, the regulator 5 Volt power line in 6502 was down. 1N4005 diode fails.

I replaced these two components and PET to restart:



If this can help.

Bruno.

Thanks Bruno,

Druid sent me some advice, which I'm slowly working through. Certainly the board is much cleaner now and all of the rust is gone.

Unfortunately the "garbage screen" symptom could be almost anything, but while waiting for a board to appear I am slowly trying a few things. I'll do a few more checks on the power.

I'm actually in Australia right now. Life has been hectic lately and the vintage computer hobby has gone on the back burner.

Tez

Hello Tez,

At your service. I'm french, and passionate collector of the Commodore brand since 1981.

I went to Australia in September 2006 for a month, very beautiful country!

Good luck to spread your PET.

Currently, I started restoring a 2001 PET.



See you soon.

Bruno.

Nice Pet Bruno,

I would have loved a 2001, as they are the "original" Pet but none seem to ever appear on the market here.

My wife and I are in Melborne for a few day's holiday. Back to New Zealand on the weekend.

Cheers

Terry

Today I salvaged one more PET, a 4032 model that showed no sign of life when I powered it on. Since those models don't have an internal beeper to indicate life, I thought hard how to determine whether it was the power supply, motherboard and/or monitor that had gone bad. Then it struck me: attach a floppy drive. Those blink their LEDs when the computer is powered on. So I connected a 8250LP drive I had nearby, and just as expected nothing happened.

Fortunately I had a spare power supply from a 8000 series PET, that electrically uses the same PSU as the 2000, 3000 and 4000 series PETs it seems. However the wires to the monitor were cut off, but that's a problem to fix later. First I had to remove the old power supply, which is a story in itself. The supply is screwed onto a metal plate, but actually one should not separate those as it all comes loose as a unit. Instead there are two screws from the inside one removes, then two from the back side. The power supply also features a gigantic capacitor attached with cable tie, that I had to cut loose.

But still it wouldn't let go. Three ground wires were attached to the case, underneath the motherboard and in a way not accessible from the outside! So I had to remove the board, then using a small wrench unscrew the bolt and get the wires free. Finally!

Attaching the replacement power supply went in the other direction, but much faster now when I knew all the steps required. It also has a huge capacitor which I will need to use a fresh cable tie to fasten. Time for the power on test - will it smoke, go BANG or work as expected? Yippie, it powered on nice and easy.

Now for the monitor power, two thin wires that ideally should be soldered onto the power supply. Instead of fiddling with a soldering iron, I grabbed two slices of screw type terminal block and merged the wires. Ooh, will that be enough? I powered it up again and:

### COMMODORE BASIC ###
31743 BYTES FREE
READY.

Wow! Unfortunately the keyboard is rather dull, but I know how to take apart those and clean to full function. I'll conduct more testing later, but it looks promising.

It also means since I'm in the middle of working, I can try a different motherboard to have something to offer Tezza, thus I wrote in this thread. :-D

Update: Ok, two motherboards tested OK. Since the latter one is equipped with Basic 4.0 and lower case characters, I installed it into the 4032 and will trade the other first one.

tezza said:

Nice Pet Bruno,

I would have loved a 2001, as they are the "original" Pet but none seem to ever appear on the market here.

My wife and I are in Melborne for a few day's holiday. Back to New Zealand on the weekend.

Cheers

Terry

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those have been sold occasionally in germany and here in sweden over the years, but all my attempts to get one have failed due to those pesky last-second snipers. aaarggg!

and a guy in germany sold 3 non functional PET 2001's, without the datasette not so long ago, so they show up every now and then.

i had some urge to play with my PET 2001 after reading through this thread, so i get it out of storage and plug it in and is met by this: