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IBM 5153 (CGA monitor) line voltage range

andrew96

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I have managed to find a diagram online but it was not quite the same! so over the weekend I have modified it so now the circuit IS the same as the PWB-811 board BUT the diodes are what was on the diagram originally! the 2 zener diodes ARE updated to what my board contains as well as the transistors, the resistor values have been tweaked as well as these differed slightly. hers is the diagram so far......

modified.jpg
 

modem7

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So basically it took out D817, R821, R809, R823, D820, Q802 2SB739 and of course Q801 2SD1185!

it is a Tatung PWB-811 psu

The reference that I have PM'ed to you may help.

Also, I have a PWB-811 board right in front of me now, from a 5153 that has been used by somebody for parts. Unfortunately, most of the board's diodes (the ceramic? encased ones) have disintegrated, and some components, some of which will ring-a-bell to you, have been removed: R801, R808, R821, R809, R823, Q802, Q801

I have a working 5153 monitor, and will look in that later to see if it has a PWB-811 board.
 

andrew96

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I just woul;d like to say many thanks to all that have PM'd me with info on the damaged bits! it has been a great help! updates coming soon!!!
 

andrew96

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The reference that I have PM'ed to you may help.

Also, I have a PWB-811 board right in front of me now, from a 5153 that has been used by somebody for parts. Unfortunately, most of the board's diodes (the ceramic? encased ones) have disintegrated, and some components, some of which will ring-a-bell to you, have been removed: R801, R808, R821, R809, R823, Q802, Q801

I have a working 5153 monitor, and will look in that later to see if it has a PWB-811 board.

ah!! that seems to ring true with what fails!!!!

if it still has the small redish diodes D820 and D817 in place, could you have a look to see as one of these is 2 is slightly different to the other, one has T3 on it and the band is closer to the edge of the diode than the other, and the other is the same as D812, D813.

the reason I cant remember which is which is I took these bits out in 2015 and can't now find the it of paper I wrote which was which!!!! but I have he diodes still!!! I do think is is D821 which is the 'T3@ different diode, but if you do have the PWB-811 board there that would help me a lot just to confirm which is what!!

many thanks in advance
Andrew
 

andrew96

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Well thanks to everyone that PM'd me I have now found out the 2 grey resistors marked 1100 and 1229 are 10r and 2.2r 1/2w fusible resistors
 

andrew96

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andrew96

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I have now opened up the counterfeit transistor 2SD1185 and indeed it is very fake! when it blew it melted the internal connections off from the semiconductor to the pins! no wonder I got a totally open circuit from it once it blew! normally they go short circuit when these beasties go! going to open up the original transistor tomorrow then will post what the differences are and what to look out for once I can post without having to wait for the post to be approved! (10 post count) so if anyone is intending to buy 2SD1185 transistors watch out for the fakes on the market!
 

andrew96

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I know chips are counterfeited, had a fair few of those! but no idea they did TO-3 transistors as well! keeping these old things running is quite a nightmare really when all these things are set to push you back when it should not be that hard!
 

andrew96

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So before I cut the top off the old transistor, here it is pictured next to 2 I believe to be genuine 2SD1186 transistors! the 1186 is slightly better as has a higher collector emitter breakdown voltage and for me was slightly easier to get hold of than the 1185.

IMG_1309.JPG
 

andrew96

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I have now managed to identify all except one diode!

looks like it has a '3' on it and a curved type of 'T' it is Do-35 case style and resides in position D820 in the power supply board. any one have any idea what this diode is?? it is all that is stopping me getting this running!

any help would be great!!! many thanks in advance

IMG_1327.JPG

IMG_1323.JPG
 
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andrew96

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bigger view of the diode!

IMG_1333.jpg IMG_1334.jpg

I believe them to be made by Hitachi as all the other semiconductors appear to be.

the closest I have found so far marked with a '3' is a 1SS199 but the cathode band is green and not black, also the diode package is too small!

the search continues......
 
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modem7

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There are members here with varying levels of electrical engineering knowledge.
One may be able to suggest a replacement based on where D820 is in the circuit ([here]).
 

andrew96

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OK well on doing some research, I have found the diodes with just a black band such as D812, D813, D817 to be 1S1555 (35v 300ma general purpose diode) and the marked diode with a 'T3' D820 to be a 1S1553 which has a 70v 300ma rating general purpose again, so easily able to substitute both with the more common 1N4148 diode!

I am much happier knowing the original diode ratings!!

1s155x.jpg

(not sure why the picture is so small on this forum!! any way of making it bigger??)

pdf HERE
 
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andrew96

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Don't get these! they are far too small! discovered it is 1w fusible resistors actually fitted on the pcb, I managed to work out the numbers written on them, the first (1) is for 1w then the value (10) and then the (0) is the multiplier, so 1w 10r = 1100

IMG_1318.jpg

now for the 1229, well again the first (1) is for 1w, then (22) the value and because the multipliers normally go from 0 to 6 and go to the right to add zeros, they have used (9) to move the decimal place one to the left! so the value becomes 1w 2r2

IMG_1320.jpg

these are both fusible resistors, easy when you know how!! I deduced this from 120r I had in my spares box of the same type marked 1121 and the physical size of them!
 
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andrew96

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To update this thread, I've given up on the 5153's antique and inefficient power supply. Even though I got it to work on 230VAC, it runs warmer than I'm comfortable with.

Standard industrial power supplies are nearly impossible to find with a suitable output voltage and power rating but some came up on eBay a few weeks ago. There are seven left if anyone else is contemplating this moderately-difficult upgrade. The unit is of adequate quality, the price is right, the output is clean and stable and can be easily adjusted from the specified nominal 110VDC up to the ideal 115VDC. It's rated at 100W and the 5153 needs roughly 60W. It has an internal switch for 100-120/200-240 VAC input.

Aside from implementing mounting and wiring, the original degauss circuit (just one component, a PTC resistor) needs to be cut from a corner of the old PCB and mounted somewhere where it can dissipate heat (first pic at the top.) Also a main fuse should be added just after the monitor's power input.

View attachment 37382 View attachment 37383

Fantastic! I bought one of these just in case I had no joy with the original! It arrived today but its construction is not great! In the post the coil has come dislodged from the main board, It seems the solder strength is not great! So if you do get one examine it thoroughly before fitting and test it first is my advice!


here in the UK it cost me £53 with shipping! Expensive to have it arrive broken!
 
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paul

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Mine arrived with one corner of the aluminium frame bent. As I mentioned, I thought the quality was adequate, but certainly not as good as common Chinese brands such as Meanwell. However, I've never seen another PS with this particular output voltage, 110VDC. It seems that LED lighting applications are why they produce it.

I also had originally enquired as to the adjustable voltage range. The vendor's salesman told me it wasn't adjustable (and wanted to quote me for a custom design) but I knew pretty much every industrial PS is, and so took a chance that I could squeeze 5 more volts out of it, which it easily handled.

If you're willing to forgo the originality of having the original PS (an awful piece of engineering, IMO,) I think this option will result in a much more reliable vintage monitor.

What I found interesting about my 120VAC-only model is that the degauss circuit worked perfectly well on 240VAC without mods. I would have thought the coil impedance would be a problem but the PTC arrests the current fast enough so that it doesn't matter.

P1010858.jpg
 
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andrew96

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Yes even back in the day of CRT tv's the UK and US model used the same positors for degaussing, they just take longer to heat up and stop the current on 110v, on 240v they was passing current for less than a second! they also used to suffer here in the uk as the round elements inside would sometimes break up or the edges would crack off then there would be a flashover inside and blow the mains fuse! was quite common on some sets!!
 

andrew96

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The 3R3 10W resistor on the long standoffs appears not to be around these days, so what I did was to buy a normal axial 10w leaded variety, top resistor is the original bottom is the leaded type

IMG_1310.jpg

I then cut the standoffs off and spaced them the same distance apart as the original, wrapped the wires round the end of the new resistor (making groves in the end so the wires wrap round without any sharp bends) then soldered the wires to the standoffs!

IMG_1311.jpg

It doesn't quite have the solid feel of the legs the original have, but when soldered in the board the mechanical strength is quite good! As mine is the PWM-811 pcb the wire at the ends are no where near the metal case, but if you have the other type of psu where the end is near the metal case then make sure there is no way it can touch or short out on that!
 

andrew96

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New fusible resistors have arrived, I ended up buying NFR1W10R and NFR1W2R2 fusible metal film resistors

IMG_1351.jpg

once bent into shape and length..

IMG_1352.jpg

not much more to do now!!! :eek:nfire:
 

andrew96

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Everything now fitted, powered it up with my dc current limited power supply! at just over 70v it started to spring to life and at 95v got the full 115v output from it! it seems to regulate fine and am now back to where I was originally with it! just got to pluck up the courage to apply full 230v ac to it at somepoint! but for now I am pleased it works again!!

Many thanks to everyone that helped me along the way!

Have now turned up the dc power supply to 300v and it survived fine! so it does look like I now have a genuine 2SD1186 transistor!

Andrew

IMG_1359.jpg
 
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