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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 15th Dec 2023, 12:14 am   #1
ScottishColin
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Default Commodore 8026 printer / typewriter

Attached are a few photos of the Commodore 8026 daisywheel printer / typewriter that I have recently picked up.

It has an IEEE-488 interface on the back and is actually an Olympia ESW 103 with an extra Commodore PCB inside it.

This is what I'll be moving on to once the 8032 is finished (and monitor adjustments aside, I think we're pretty much on the home straight now).

I think it's quite possibly the most beautiful printer I have ever seen and I really want it to work, but I know that may not be possible, but I'll give it a go.

There's no schematics available that I can find so we're a bit blind there.

Problem number two - I think these (see photos) are batteries and they have leaked over the years and left a blue deposit on other components.

How do I clean this deposit and is it perhaps going to be terminal / problematic for the other components or the PCB?

Colin.
Attached Files
File Type: zip PXL_20231214_204053153.zip (2.67 MB, 84 views)
File Type: zip PXL_20231214_204603543.zip (2.62 MB, 58 views)
File Type: zip PXL_20231214_204713747.zip (2.48 MB, 48 views)
File Type: zip PXL_20231214_204736776.zip (2.43 MB, 43 views)
File Type: zip PXL_20231214_204814132.zip (2.46 MB, 57 views)
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Old 15th Dec 2023, 1:12 pm   #2
Phil__G
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Default Re: Commodore 8026 printer / typewriter

Earbuds dipped in white vinegar have always worked for me Colin
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Old 15th Dec 2023, 1:48 pm   #3
SiriusHardware
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Default Re: Commodore 8026 printer / typewriter

(As long as you take the batteries out of the earbuds first).

The green tinge on nearby metalwork suggests acidic vapour damage to me, not sure if treating it with another acid is the way to go? It would be the logical thing to use on leakage from Alkaline batteries, of course.

It's also a priority to remove those batteries as soon as possible before they eat anything else - is there anything to show what voltage they originally were?
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Old 26th Dec 2023, 5:34 pm   #4
ScottishColin
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Default Re: Commodore 8026 printer / typewriter

Happy Christmas all.

I've been looking at the two 8026 PCBs today and I know they need cleaning up and the batteries removed, but I was thinking of drawing out the schematics as they don't seem to exist anywhere I can find.

I've never done this before so it may be a fools errand, but I was wondering if there is any software out there for beginners that will help with this?

Thanks.

Colin.
Attached Files
File Type: zip PXL_20231226_162815706.zip (3.17 MB, 48 views)
File Type: zip PXL_20231226_162931577.zip (2.58 MB, 39 views)
File Type: zip PXL_20231226_162950603.zip (2.49 MB, 31 views)
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Old 26th Dec 2023, 5:49 pm   #5
TonyDuell
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Default Re: Commodore 8026 printer / typewriter

I've drawn out a few schematics over the years and have yet to find a CAD system which actually 'aids' me. Rather, I use what I call a 'paper aided design' system, or 'pad' (of plain paper).

My main tip for doing this is to find a way to identify the main components on the board -- the ICs, maybe transistors, etc. If they're labelled in the etch or silkscreen then use that, otherwise sketch a layout diagram (or take a clear photo) and number that.

Then make a list of said components and their sections (in the case of multple-gate ICs, for example). The list will be something like :
U1 6502
U2 a b c d '00 [I use 'xx to mean 74LSxx etc)
U3 2114
U4 2114
U5 '138
U6 a b c d e f '04
....


Start drawing out based on something known, like the processor. That's going to be used in essentally one way (it needs a clock signal, reset, will connect to the address and data buses, etc), whereas a NAND gate could be just about anything. As you draw out each device, cross it off the list. That way you won't forget a section, or do something twice.
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Old 28th Dec 2023, 6:58 pm   #6
ScottishColin
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Default Re: Commodore 8026 printer / typewriter

Thanks Tony. I'll give it a try although I'm going to need help with the ICs I don't recognise, along with some other components I haven't seen before.

Colin.
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Old 28th Dec 2023, 7:02 pm   #7
ScottishColin
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Default Re: Commodore 8026 printer / typewriter

OK - batteries out to allow me to start cleaning.

They have three legs on them - see attached photos.

They are marked:

+188 8137
41B025AC00301
ASM IN MEXICO

Anyone recognise these?

Colin.
Attached Files
File Type: zip PXL_20231228_175637555.zip (2.80 MB, 44 views)
File Type: zip PXL_20231228_175648737.zip (2.10 MB, 38 views)
File Type: zip PXL_20231228_175655371.zip (2.08 MB, 33 views)
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Old 28th Dec 2023, 9:50 pm   #8
SiriusHardware
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Default Re: Commodore 8026 printer / typewriter

I'm afraid I can't find a thing on those - due to the age of the unit and that greenish tinge afflicting all of the nearby metal surfaces, I think they are Nicad but that is only conjecture on my part.

Which board are those batteries on, the Olympus PCB or the added Commodore PCB?

If they are on the Olympus PCB then it may be possible to hunt down the diagram for the host printer (Olympus ESW 103). If it's the add-on Commodore PCB then it should have the usual long part number somewhere on the PCB - maybe we can find the diagram for that if we all look hard enough.
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Old 28th Dec 2023, 11:22 pm   #9
ScottishColin
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Default Re: Commodore 8026 printer / typewriter

They're on the Olympia PCB.

Photos attached of the part number of each PCB attached.

Colin.
Attached Files
File Type: zip Commodore PCB.zip (599.0 KB, 40 views)
File Type: zip Olympia PCB.zip (2.71 MB, 37 views)

Last edited by ScottishColin; 28th Dec 2023 at 11:31 pm.
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Old 29th Dec 2023, 12:12 am   #10
SiriusHardware
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Default Re: Commodore 8026 printer / typewriter

'Olympia', not 'Olympus' as in Cameras, sorry. Still drawing a blank but maybe if you ask on a specialist typewriter forum - there seem to be a couple at least - someone there may be able to drag out the ESW 103 diagrams for you, or if not they may at least know what voltage and chemistry those batteries are.

Aside from the obviously duff batteries, does it actually function as an electric typewriter? If not, what symptoms or life signs if any do you have on the unit?
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Old 29th Dec 2023, 1:37 pm   #11
SiriusHardware
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Default Re: Commodore 8026 printer / typewriter

Neither of the PCB part numbers (shown in the pics attached to #9) follow usual Commodore numbering practice, but both commence with "67.... suggesting that they were both produced by the same design 'house'.

By all means try to trace out the diagram, but you can also begin checking out the more basic stuff such as the power supply / power input to regulators / voltages coming out of the regulators.

Does your STAG programmer have a 'chip test' mode on it - something I should have asked you before when we've been working on your PETs. Very often high end device programmers like that have a tester mode in which you can insert and check (most) 7400 and 4000 series logic ICs for basic functionality.

If it comes to it you can try to brute-force a repair by removing and checking every component which can be checked and replacing everything else - one company I worked for used to specialise in repairing things that way because usually we just had a PCB and not the unit it went into, so it wasn't usually possible to power the PCB up and fault trace it in the normal way.

But as I am fond of saying, always check the easy stuff first (power supplies, states of the clock and reset circuits in any microprocessors which are present). If you don't have specific circuit diagrams then you have to go looking for IC data sheets and application notes showing typical usage of the ICs, including regulator ICs, to determine which pins are used for what. Very often the circuit surrounding a particular specific-purpose IC will not be much different from its manufacturer's example application circuit in the datasheet for the IC.
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Old 29th Dec 2023, 5:25 pm   #12
ScottishColin
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Default Re: Commodore 8026 printer / typewriter

So I haven't been brave enough to turn it on yet. After I've cleaned things up a little I guess that's next.

Colin.

Quote:
Originally Posted by SiriusHardware View Post
'Olympia', not 'Olympus' as in Cameras, sorry. Still drawing a blank but maybe if you ask on a specialist typewriter forum - there seem to be a couple at least - someone there may be able to drag out the ESW 103 diagrams for you, or if not they may at least know what voltage and chemistry those batteries are.

Aside from the obviously duff batteries, does it actually function as an electric typewriter? If not, what symptoms or life signs if any do you have on the unit?
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Old 29th Dec 2023, 5:31 pm   #13
ScottishColin
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Default Re: Commodore 8026 printer / typewriter

No test mode that I am aware of on the Stag PP39. I'll dive into the manual and take a look.

The only two ICs that are socketed are:

One marked F 96LS488DC (48 pin) on the smaller board which has the IEEE 488 port connected to it
One which is an HN462532 in an adapter which is marked as 2716

So if I wanted to test the other ICs I'll need to desolder them.

Let's power it on and test voltages as you say - I can see where 5V and Gnd are on the larger motherboard so I guess that's a start.

Colin.

Quote:
Originally Posted by SiriusHardware View Post
Neither of the PCB part numbers (shown in the pics attached to #9) follow usual Commodore numbering practice, but both commence with "67.... suggesting that they were both produced by the same design 'house'.

By all means try to trace out the diagram, but you can also begin checking out the more basic stuff such as the power supply / power input to regulators / voltages coming out of the regulators.

Does your STAG programmer have a 'chip test' mode on it - something I should have asked you before when we've been working on your PETs. Very often high end device programmers like that have a tester mode in which you can insert and check (most) 7400 and 4000 series logic ICs for basic functionality.

If it comes to it you can try to brute-force a repair by removing and checking every component which can be checked and replacing everything else - one company I worked for used to specialise in repairing things that way because usually we just had a PCB and not the unit it went into, so it wasn't usually possible to power the PCB up and fault trace it in the normal way.

But as I am fond of saying, always check the easy stuff first (power supplies, states of the clock and reset circuits in any microprocessors which are present). If you don't have specific circuit diagrams then you have to go looking for IC data sheets and application notes showing typical usage of the ICs, including regulator ICs, to determine which pins are used for what. Very often the circuit surrounding a particular specific-purpose IC will not be much different from its manufacturer's example application circuit in the datasheet for the IC.
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Old 29th Dec 2023, 5:53 pm   #14
ScottishColin
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Default Re: Commodore 8026 printer / typewriter

There's some more information here where there seems to be an 8026 expert (although the thread is nearly ten years old). Google translate does seem to do a good enough job German->English:

https://www.forum64.de/index.php?thr...und-reparatur/

Colin.
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Old 29th Dec 2023, 8:57 pm   #15
TonyDuell
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Default Re: Commodore 8026 printer / typewriter

Just looked at the photos of the PCBs.

Am I correct that there are just 2 PCBs in the thing. The larger one which had the batteres on it, and the smaller one with the 96LS488? If so then if it were mine I'd draw out those circuits in a day or so.

The 96LS488 is what the number implies, an IEEE-488 (GPIB, HPIB) interface. I had no trouble downloading a data sheet. The smaller PCB seems to be the GPIB interface with a normal-ish parallel interface to the rest of the machine.

On the larger board, is the EPROM in the piggyback socket of a development-type microcontroller? It looks that way, and there's no obvious processor elswhere.
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Old 29th Dec 2023, 9:06 pm   #16
ScottishColin
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Default Re: Commodore 8026 printer / typewriter

Yes - just the two PCBs.

According to the web site below, the EPROM is soldered/connected over another IC.

According to post #10 here:

https://www.forum64.de/index.php?thr...und-reparatur/

It's a Mostek CPU.

Colin.

Quote:
Originally Posted by TonyDuell View Post
Just looked at the photos of the PCBs.

Am I correct that there are just 2 PCBs in the thing. The larger one which had the batteres on it, and the smaller one with the 96LS488? If so then if it were mine I'd draw out those circuits in a day or so.

The 96LS488 is what the number implies, an IEEE-488 (GPIB, HPIB) interface. I had no trouble downloading a data sheet. The smaller PCB seems to be the GPIB interface with a normal-ish parallel interface to the rest of the machine.

On the larger board, is the EPROM in the piggyback socket of a development-type microcontroller? It looks that way, and there's no obvious processor elswhere.
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Old 29th Dec 2023, 9:11 pm   #17
ScottishColin
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Default Re: Commodore 8026 printer / typewriter

Having removed a connector that I had trouble getting off, it looks like 3 capacitors have disintegrated.

The last photo on post #2 shows what should be there (at a distance):

https://www.forum64.de/index.php?thr...und-reparatur/

Attached is the photo of my PCB...do I need to try to find out the exact replacements or is there any safe way of guessing what I should use?

Colin.
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File Type: zip PXL_20231229_195319184.zip (2.36 MB, 31 views)
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Old 29th Dec 2023, 9:19 pm   #18
ScottishColin
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Default Re: Commodore 8026 printer / typewriter

The capacitors are connected to three pins/wires that go to the PSU. The PCB has markings for two of the three pins.

Grey wire is 9v
Red is not marked
Brown is 5V

Colin.
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File Type: zip PXL_20231228_1724514822.zip (252.7 KB, 38 views)
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Old 29th Dec 2023, 9:20 pm   #19
TonyDuell
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Default Re: Commodore 8026 printer / typewriter

Mostec made some F8-series microcontrollers with internal masked ROMs. With those, you were limited to the ROM in the device, there was no way to add program ROM by connecting it to the device's pins. And of course the ROM had to be programmed when the device was made.

They also sold 'development' versions of at least some of them. These had a 24 pin socket on top of the package. It was internally connected to the chip, it was not simply wired to the normal pins that go into the PCB. These devices had no internal ROM, rather you put a programmed EPROM in that socket which behaved as the internal ROM of the standard devce.

I suspect that's what you have here.
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Old 2nd Jan 2024, 12:53 pm   #20
ScottishColin
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Default Re: Commodore 8026 printer / typewriter

Happy New Year all.

I've pulled out the (heavy) PSU and tested its output.

It has a five pin connector that goes to the motherboard and I've removed it.

The connector is as follows along with the markings on the motherboard:

Pin 1 Black - no marking
Pin 2 Grey - +9V
Pin 3 Red no marking
Pin 4 Brown - +5V
Pin 5 Blue - GND

Actual readings are as follows:

Pin 1 - no reading
Pin 2 - +10.5V
Pin 3 - +39V
Pin 4 - +4.9V
Pin 5 - Ground

There are two glass fuses in the PSU both of which are OK.

So it looks to me that the PSU is functioning (albeit a slightly high +10.5V vs a marked +9V) and an interesting +39V that isn't marked on the motherboard.

Is it possible to assume that the PSU IS OK?

If I traced where the capacitors are on the board would that give me any clues as to their value?

Colin.
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