Commodore 1901 colour monitor repair...

Thanks for that! So with the 180 (straight out the back, I guess) connector, I need to install with the wider bit to the bottom, then connect the top row of pins on the connector to the row nearest the back, and the bottom row of pins furthest away?

This is what I'm going on - http://elgensrepairs.blogspot.co.uk/2012/12/finding-repairing-and-enhancing.html . If you've got any more pics of the scart and connection that would be great!
 
no check the link i gave here,180 degree is opposite to 90 not straight out the back


i have seen that link and that was a straight out pin socket he had already i suggest you get a socket in the link i provided,no guesswork required and just simply solder it in,simple

why have all the extra work of wiring a socket with 21 pins? when you can get a socket made for the job?
 
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Finally getting around to fitting the scart socket... Found that CP2 has disintegrated! It`s a paper capacitor next to the power switch that has exploded, so that needs replacing.

Other than that it looks straightforward to fit - everything`s there already to go and the connectors are in the right place, thanks Roy! I`ve had to cut the side mounts off to get it to fit and I think I may need to shave a bit off the back to rotate it into the holes whilst the metal surround is still fitted.
 
I'm very late to this thread, but I also just installed a SCART port into my 1901 after replacing all of the capacitors (the image was shaky after 15mins of use, this appears to be fixed now). However there's another problem that's ticking me off a bit:

69871202_387125568644868_293969161128771584_n.jpg

This is my USA SNES connected via RGB SCART. Notice the gap to the right? Well that's with the horizontal position POT turned all the way in that direction... The 1901 has no POT for horizontal amplitude adjustment.

It does have vertical amplitude (and v-sync) but no vertical position - who the hell designed this thing?!



Super late edit: I ended up just adjusting the positioning rings on the yoke and got it to where I wanted it. It's interesting to note that despite being near identical internally to this Commodore 1901, my Thomson 4165 (similar to the Thomson 4120) has a much thinner horizontal amplitude when displaying 60Hz analog RGB...
 
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i just bought this monitor for 10 euros i want to do the scart mod any one has a link to the correct scart socket ? thanks
 
ive just finished repairing a commodore 1901 monitor i got here off macc.

it had loads of problems due to old age,but is now fully working with some extra features.:)

when i got this it had a bad mains switch that had fused contacts but that wasnt the end of this so i had to repair it.after the repair.

this had no colour on luma/chroma and was displaying black and white and needed a real overhaul as it had alot of problems switching between pal/rgb modes,so i thought i would service it and add a few nice features.

such as:
colour on composite:)(i will document this later) its black and white normally...very interesting this one.
scart for rgb analogue input its digital rgb i normally as well on a 9 pin d sub as standard for the commodore 128 rgb output...
chroma luma repair with colour fix

interesting really, this monitor as its actually a thomson internally.

i will post a few pictures with various inputs being used to show the display quality and pictures of the front and rear,i will still have to fix the front flap as it has broken hinges...i'll do that at a later date as ive been very ill.
and a parts list of what i replaced and added to make this monitor really useful...

more later chaps...

here is a list of parts:

parts added:
1 toggle switch(was going to use a push to make latch switch but i havent got one )
1 scart socket

parts replaced:
1 mains switch(fused contacts monitor could not be turned on)
1 AN 5620 X (PAL)(on pal/rgb module) replaced to extend the life of the monitor)
2 BU508D's(tired components)
1 7812 regulator(as above)
1 TEA 2017(partly failed)
1 TDA 3506(replaced to extend life)
1 2K trimpot(i broke the original during the repair,doh)
removed one resistor grounding the chroma signal hence why it was black and white on luma chroma,cant remember the value.its on the back of the chroma port..didnt replace its not needed...
1 1.6 amp fuse due to corrosion.

i may also make a nice wiring loom for the tube neck assembly at a later date,original looks tired..

i'll upload pictures and descriptions later for anyone interested.no pictures of the actual repair that was a long night so didnt bother..
Hi! I will revive this old thread. I just hooked up 1901 and it went smoke. Ofc X2 cap. I have a question about TP02 transistor - bc639 - you can clearly see the pcb is darkened in this spot. A lot of heat around this transistor. Any ideas if I should put a new one? It must have been stressed hard.
 

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Hi! I will revive this old thread. I just hooked up 1901 and it went smoke. Ofc X2 cap. I have a question about TP02 transistor - bc639 - you can clearly see the pcb is darkened in this spot. A lot of heat around this transistor. Any ideas if I should put a new one? It must have been stressed hard.
thats part of the power supply circuit,im a little worried that could be carbon tracing at some point,can you check the zenner is ok at location DP09,while its off
it feeds the base of that transistor
and check the capacitor CP13 see if its shorted or going bad
 
thats part of the power supply circuit,im a little worried that could be carbon tracing at some point,can you check the zenner is ok at location DP09,while its off
it feeds the base of that transistor
and check the capacitor CP13 see if its shorted or going bad
Thank you! Should I remove zener from the circuit? I can check CP13 with my ESR multimeter. Should I also remove it from circuit? Should I check BC369?
 
Thank you! Should I remove zener from the circuit? I can check CP13 with my ESR multimeter. Should I also remove it from circuit? Should I check BC369?
yeah remove it from circuit,i just remebered how old this thread is,wow
if it wasnt for the new forum layout,i would never of seen your comment
to be honest ,im not sure why that transistor would get hot,but your woelcome to change it if you like
 
yeah remove it from circuit,i just remebered how old this thread is,wow
if it wasnt for the new forum layout,i would never of seen your comment
to be honest ,im not sure why that transistor would get hot,but your woelcome to change it if you like
I'm glad you did. My knowledge is limited. I have soldering skills but transistors is not my thing.
Would you say that this situation in the circuit is not normal? It should not be that hot? It looks like it is pumping a lot of current.
Maybe replace zener (on the schematic it is 11v I think?), transistor and Capacitor altogether? :)
 
yes,ill have to get back to you as to what the zener is,is that ok,lets say tomorrow
 
some of the text in the servixce manual is a bit hard to read
Roy I will also write here so it is documented for the other generations :D
Zener diode is BZX 83C - what value? Idk probably 11v. I need to check today.
Cap is 1uf/50v I guess.

From service manual >> TECHNrCAL DESCRIPTION SWITCH MODE POWER SUPPLY HORIZONTAL AND VERTICAL SCAN CIRCUITS The SMPS works from 220 AC to 240 AC at both 50 Hz and 60 Hz frequency with an output power of 50 watts. The output voltages available are 114V and 24V. The 114V is used for the line output stage whereas the 24V is used for the oscillators, line driver stage and video processing stage. The supplies for sound, heater and video output amplifier are then tap from the out put line transformer. The AC mains voltage is applied to line filter LP01 via an on-off switch and a fuse which provides overload protection. This voltage is then rectified by DP01 to DP04 and partially filtered by CP04. The resulting DC voltage then acts as a supply voltage for switching transistor TP01 which is controlled by 1C TDA During start-up time, the 1C 4601 is supplied from the mains through RP12. However, in normal operation, the voltage will be tap from windings 11/9 of the switch mode transformer. For low input supply voltage, the switch on time will be delayed by resistor RP12, hence a speed up circuit is necessary. This comprised of tran sistor TP02 and its surrounding components. The variation of output voltage is simulated by the feedback control winding 1/9. This voltage is rectified by DP05 and applied to the amplifier input pin 3 of control 1C
 
Roy I will also write here so it is documented for the other generations :D
Zener diode is BZX 83C - what value? Idk probably 11v. I need to check today.
Cap is 1uf/50v I guess.
yes thats right,zener is a 11 volt 0.5 watt part
talking to you in two places is a bit odd,havnt done that for someone in years,lol
 
yes thats right,zener is a 11 volt 0.5 watt part
talking to you in two places is a bit odd,havnt done that for someone in years,lol
lol true :D thanks for help either way. Could you tell me if this diode would be ok?

 
what you could do,if you remove the transisotr see if that black mark wipes off with ipa,if not i think id be concerned about carbon tracing
 
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