Trying to fix an Atari XLF 800 Freddie

[ataridns]

Greetings to all , I am new to Atari but very old to retro computers. They are excelent machines to explore. I took a problematic ATARI 800 XLF from ebay. This is its story...

 

I have an atari 800XLF freddie pal and I have a PROBLEM with frequencency at Y2. The Atari has no signal screen with blinking sound at vga out and garble - black screen at RF out. 

I measure the crystals out off board and they were as it should be, BUT in the board the Y1 is measuring ok and the Y2 measures 443Khz which is 4,43Mhz divided by 10.

Is it normal ? I replaced the two near to clock sn74LS... gates also but nothing.

 

At my attached pics are:   1-the Freddie Board     2-The Y2 hooked,    3 - Y2 measure,    4-Y1 hooked,   5 Y1 measure,   6 an other output frequency measure output for GTIA maybe

 

The machine came with missing 1st dram chip and I put a new MT4264 while the other 7 drams are KM4164 . I am intending to add sockets for all 8 drams and change them all for being sure soon. 

Also I changed the big caps and the DC voltage in board is 4,7. 

 

Could you recomend me any solution or what I can check ? 

Thank you! 

[Beeblebrox]

don't discount a bad freddie chip, bad cpu and also mtram chips aren't a good dram to use as notorious brand. 

[ataridns]

I am waiting about km4164B Samsung drams,

so 1st is to test these using sockets. Also my mix KM4164A with MT4264 is not good as I have seen in the address and data lines in my scope.

2nd, I have a working XL 800 Atari and I can try swap the 5 main chips : GTIA      POKEY ANTIC     SALLY     PIA    except Freddie because I have not any Freddie. Then I will see whats going on..

 

But.... this measurement is it right? Why it is ON THE CRYSTAL LEGS a different divided by ten frequency ? WHY? 

 

 

Edited March 17 by ataridns

[TGB1718]

1 hour ago, ataridns said:

But.... this measurement is it right? Why it is ON THE CRYSTAL LEGS a different divided by ten frequency ? WHY? 

Sometimes, just putting a probe on the leg of a crystal will cause it to become unstable, is there another place to check

the frequency after passing through some other device ?

 

[ataridns]

I dont know even if it is normal. And why the Y1 crystal seems ok and the Y2 is divided at his own legs ? It gives this freq and in other places , the input of GTIA in some pins of freddie , and also somewhere It transforms to its half like in pic 6 : 221,75KHZ

Edited March 17 by ataridns

[TZJB]

FØ0

On 3/17/2024 at 7:03 PM, ataridns said:

Greetings to all , I am new to Atari but very old to retro computers. They are excelent machines to explore. I took a problematic ATARI 800 XLF from ebay. This is its story...

 

I have an atari 800XLF freddie pal and I have a PROBLEM with frequencency at Y2. The Atari has no signal screen with blinking sound at vga out and garble - black screen at RF out. 

I measure the crystals out off board and they were as it should be, BUT in the board the Y1 is measuring ok and the Y2 measures 443Khz which is 4,43Mhz divided by 10.

Is it normal ? I replaced the two near to clock sn74LS... gates also but nothing.

 

At my attached pics are:   1-the Freddie Board     2-The Y2 hooked,    3 - Y2 measure,    4-Y1 hooked,   5 Y1 measure,   6 an other output frequency measure output for GTIA maybe

 

The machine came with missing 1st dram chip and I put a new MT4264 while the other 7 drams are KM4164 . I am intending to add sockets for all 8 drams and change them all for being sure soon. 

Also I changed the big caps and the DC voltage in board is 4,7. 

 

Could you recomend me any solution or what I can check ? 

Thank you! 

 

Hi @ataridns welcome to AtariAge.

 

I had a nightmare of a 800XLF. It now works fine. See here:-

 

 

As to your problems, you have done the right thing and replaced C13 and C14 however you have not said where you have measured the 4.7V potential.

 

If it is at the J7 socket your power supply is much too low for a 800XLF as the inductors L3 and L4 reduce the voltage further. You require 5V to 5.2V at J7.

 

In fact L3 should be short circuited as it feeds Freddie. If you look at my pictures, L3 was shorted out from the factory and increases the voltage to Freddie on the +5VB supply. Diagram courtesy of Jerzy Sobola:-

 

 

Freddie also needs a 100nF decoupling capacitor across the 5V supply as it was missed out at manufacture. You would need to supply this of course and it will improve stability. (Thanks to @tf_hh for this discovery).

 

As to clocks. DON'T PANIC. Again Freddie is the key here. Like an Atari 130XE, Freddie should be receiving a 14.18757 MHz clock on Freddie pin 2 CLK, which is divided by 4 internally and sent out Freddie pin 37 OSC OUT, feeding GTIA pin 28 OSC IN a 3.546875 MHz clock.

 

This clock is sent out of GTIA pin 20 FØ0 OUT to ANTIC pin 35 FØ0 IN and is divided by 2 to generate ANTIC pin 34 Ø0 OUT at 1.77344625 MHz. This is buffered by U18B and connects to SALLY pin 37 Ø0 IN. SALLY then creates pin 39 clock Ø2 which should appear at FREDDIE pin 5 and ANTIC pin 29 via a buffer of U18A.

 

Not sure what is going on with your PAL clock yet but 4.43 MHZ should appear on GTIA pin 16.

 

 

 

I attach the full schematic below, but beware of some mistakes. Double check everything. They are not always accurate.

 

Best of luck, hope this helps, and let us know how you get on.

 

 

ATARI800XLF-SCHEMATIC.PDF

[foft]

I've not tried this myself but I always thought the scope pictures in this looked very helpful to see what is normal or not, if you don't have access to a second system:

 

http://ftp.pigwa.net/stuff/collections/Atari documents/Service Manuals/Sam's Computerfacts Technical Service Data - Atari 800XL.pdf

[ataridns]

THANK you TZJB, and Foft for all your help. TZJB you are the man!  Your comments maybe gave me the answer where is the fault...

 

1st of all about power: My Lab psu generates 5.2v at 3a and the Atari XLF board consumes 0.62A total 3.22W. The Voltage at J7 is 4.73V , at C2 is 4.81 and through L3 comes in Freddie 4.80V - so is it necessary to remove L3 ? 

Also Yes I made the 100nF decoupling capacitor at the back side of the board like you, but I did not add the 1K resistor - I dont recall what is it for ? 

Also I have changed the two big caps C13 and c14 but not the three near switch the C2 C3 and the one between them. I believe don’t have good power ratings in my board and I think I must change all the rest of caps. 

 

*Suprisingly TZJB,  we have exactly the same boards! version etc.

Before that, I was referring to a high resolution pic from an Atari 800 XLF that had all the labels-white markings of the parts. The markings at top right are: 

CA025926-001 4-84 in the pic while ours is

CA025926-001 9-84 so 5 months later at 1984 but different in many ways! 

It was confusing to find the right parts from the schematics with that pic that had different naming in parts and joins! So don’t assume that XLF's are all the same.

Atari made many changes through time even within few months.

 

2nd About the frequencies: 

TZJB , I follow your path and yes you are right! all the path way is as you are telling,  BUT WITH DIFFERENT numbers at my board. The division by 4 then by 2 etc. but my starting frequency is not 14,187576 as it is in schematics and in your board. 

My crystal is 3.546894 MHz CO16112 which feeds the Freddie 

Freddie is receiving a 3.546894 MHz clock on Freddie pin 2 CLK, which is divided by 4 internally and sent out Freddie pin 37 OSC OUT, feeding GTIA pin 28 OSC IN a 0.887009 MHz clock.

This clock is sent out of GTIA pin 29 FØ0 OUT (not 20) to ANTIC pin 35 FØ0 IN and is divided by 2 to generate ANTIC pin 34 Ø0 OUT at 443504 KHz!!!. This is buffered by U18B and connects to SALLY pin 37 Ø0 IN. SALLY then creates pin 39 clock Ø2 which should appear at FREDDIE pin 5 and ANTIC pin 29 via a buffer of U18A.Do you remember these numbers? They are what I was measuring with my scope.

 

So my theory is due to the many XLF versions someone who was trying to fix my board used the wrong crystals.

The crystal 3.546894 MHz CO16112 is not for my board but mine needs one like yours at 14.18757 MHz and also I believe that Y2 crystal is not working or it is misworking and the 443.504 KHz measuring comming from the Freddie output somehow.

I will check it tomorrow. 

Again Thank you! 

 

[Beeblebrox]

yes, I think you are correct. The co16112 pal system clock crystal running 3.546894mhz is for stock non xlf pal 800xl and pal 600xl machines.

 

For the xe line and the xlf, (latter which is effectively running like an xe), need the 14.18757mhz pal clock Crystal, or an equivilant oscillator.

 

I'd try replacing the sys clock crystal first and if no colour on say an av composite cable, then also replace the colourburst. I have loads of colourburdt crystals if you need one.

 

 

 

 

Edited March 20 by Beeblebrox

[ataridns]

So I need the two crystals and now is the most difficult part of this fun process, find order it and wait......wait.... it...

Any ideas where to find them from Europe ? 

[Beeblebrox]

@ataridns So as I say for now just assume the colourburst is working. It's the system crystal you'll need to source.

 

If this were a pal 800xl or 600xl I'd say salvage the system crystal from an Atari 2600 Jr or another xl. But since this is the XE, aside salvaging the system crystal from another XE, I am not sure about modern equivalents in the EU. 

 

It's been discussed quite a bit here:

 

 

 

Edited March 20 by Beeblebrox

[Rybags]

All PAL XL/XE use 2 crystals.

 

AFAIK every Freddie equipped computer should use a 14~ MHz master crystal.

The 4.43~ MHz one is exclusively used to generate the colourburst as it can't be directly derived from the others.

 

It's a mystery to me why anyone with reasonable Atari knowledge would attempt to use a slower crystal in place of the 14 MHz one.

The smaller clock divisions are needed since Freddie also does the RAS/CAS sub-cycle operations which otherwise would have been accomplished with help from the delay line which it replaces among other things.

[ataridns]

It is very difficult to spot these crystals I want. 

 

I think one solution from this link it suits me because I need 2 rare crystals: 

 

The frequency generator solution! A chip that generates 3 frequencies! 

I think this is the best solution and it will generate both 2 frequencies for 800 XLF:

https://thepihut.com/products/adafruit-si5351a-clock-generator-with-stemma-qt-8khz-to-160mhz?variant=42293934981315

 

and here is how to program it

https://learn.adafruit.com/adafruit-si5351-clock-generator-breakout/wiring-and-test

 

also there are cheaper versions from china. One can try searching for si5351 i2c

 

Meanwhile I must change the caps and about the DRAMS I think I will wait for a while when the clocks will be restored.

 

Also if anybody has these crystals, 14.18757 MHz  and 4.43361875 MHz I want them!!! 

[Beeblebrox]

The pal colourburst 4.43361875 crystals are not rare and readily available and dirt cheap from mouser. 

 

https://eu.mouser.com/ProductDetail/ECS/ECS-44-20-1X?qs=CNVyLAqdhH3azVxIw5STTQ%3D%3D&countryCode=GB&currencyCode=GBP

 

I bought a load for peanuts last year. Use them for xl's and for the Atari 800 cpu personality boards when converting from ntsc to pal and need to add colourburst. 

 

The 14.18757mhz sys clock crystals - as I've mentioned - are available from alibaba. The link was in the previous thread I'd linked you to. 

 

Here is the direct alibaba link:

 

https://wtlcrystals.en.alibaba.com/product/60813231349-220265491/WTL_HC_49S_Xtal_Resonator_Quartz_Crystal_14_187576_MHz.html

 

[TZJB]

19 hours ago, ataridns said:

THANK you TZJB, and Foft for all your help. TZJB you are the man!  Your comments maybe gave me the answer where is the fault...

 

1st of all about power: My Lab psu generates 5.2v at 3a and the Atari XLF board consumes 0.62A total 3.22W. The Voltage at J7 is 4.73V , at C2 is 4.81 and through L3 comes in Freddie 4.80V - so is it necessary to remove L3 ? 

Also Yes I made the 100nF decoupling capacitor at the back side of the board like you, but I did not add the 1K resistor - I dont recall what is it for ? 

Also I have changed the two big caps C13 and c14 but not the three near switch the C2 C3 and the one between them. I believe don’t have good power ratings in my board and I think I must change all the rest of caps. 

 

*Suprisingly TZJB,  we have exactly the same boards! version etc.

Before that, I was referring to a high resolution pic from an Atari 800 XLF that had all the labels-white markings of the parts. The markings at top right are: 

CA025926-001 4-84 in the pic while ours is

CA025926-001 9-84 so 5 months later at 1984 but different in many ways! 

It was confusing to find the right parts from the schematics with that pic that had different naming in parts and joins! So don’t assume that XLF's are all the same.

Atari made many changes through time even within few months.

 

2nd About the frequencies: 

TZJB , I follow your path and yes you are right! all the path way is as you are telling,  BUT WITH DIFFERENT numbers at my board. The division by 4 then by 2 etc. but my starting frequency is not 14,187576 as it is in schematics and in your board. 

My crystal is 3.546894 MHz CO16112 which feeds the Freddie 

Freddie is receiving a 3.546894 MHz clock on Freddie pin 2 CLK, which is divided by 4 internally and sent out Freddie pin 37 OSC OUT, feeding GTIA pin 28 OSC IN a 0.887009 MHz clock.

This clock is sent out of GTIA pin 29 FØ0 OUT (not 20) to ANTIC pin 35 FØ0 IN and is divided by 2 to generate ANTIC pin 34 Ø0 OUT at 443504 KHz!!!. This is buffered by U18B and connects to SALLY pin 37 Ø0 IN. SALLY then creates pin 39 clock Ø2 which should appear at FREDDIE pin 5 and ANTIC pin 29 via a buffer of U18A.Do you remember these numbers? They are what I was measuring with my scope.

 

So my theory is due to the many XLF versions someone who was trying to fix my board used the wrong crystals.

The crystal 3.546894 MHz CO16112 is not for my board but mine needs one like yours at 14.18757 MHz and also I believe that Y2 crystal is not working or it is misworking and the 443.504 KHz measuring comming from the Freddie output somehow.

I will check it tomorrow. 

Again Thank you! 

 

 

You are very welcome.

 

I am glad you are making progress.

 

Your Lab PSU at 5.2V should read the same at J7 unless the connecting lead has a bad conductor? Also C2 should not logically be at a larger potential than J7 as it is fed from J7. Please re-check the J7 voltage reading.

 

I would definitely advise a short across L3 as it is not needed, especially with a modern power supply.

 

The resistor at the back of my 800XLF motherboard is the RAS pullup known only as RX in Jerzy's diagram. I removed it from the front as it was standing up as pictured. I mentioned it in the prose.

 

Unless there is obvious damage, the other capacitors are probably fine as 0.62A current draw is as expected.

 

I agree that the 800XLF seems to be an experiment!

 

Sorry to see that your frequencies do not match the norm. Obviously you can panic now as this would lead to a very slow Atari 800XLF! I see that you may have found a solution though so that is good.

 

Also sorry for my typo for GTIA pin 29 FØ0 OUT. I only had one glasss of wine yesterday 😁.

 

6 hours ago, Beeblebrox said:

The pal colourburst 4.43361875 crystals are not rare and readily available and dirt cheap from mouser. 

 

https://eu.mouser.com/ProductDetail/ECS/ECS-44-20-1X?qs=CNVyLAqdhH3azVxIw5STTQ%3D%3D&countryCode=GB&currencyCode=GBP

 

I bought a load for peanuts last year. Use them for xl's and for the Atari 800 cpu personality boards when converting from ntsc to pal and need to add colourburst. 

 

The 14.18757mhz sys clock crystals - as I've mentioned - are available from alibaba. The link was in the previous thread I'd linked you to. 

 

Here is the direct alibaba link:

 

https://wtlcrystals.en.alibaba.com/product/60813231349-220265491/WTL_HC_49S_Xtal_Resonator_Quartz_Crystal_14_187576_MHz.html

 

 

Thanks @Beeblebrox. Although I think the 14.187MHz crystal are in batches of 10000 minimum?

 

But I am looking at it through 1.5 glasses of wine today 🙃.

[Beeblebrox]

11 minutes ago, TZJB said:

Thanks @Beeblebrox. Although I think the 14.187MHz crystal are in batches of 10000 minimum?

 

But I am looking at it through 1.5 glasses of wine today 🙃.

Heh Heh, I noticed that also a little later today! Yes, rather rules that supplier out Heh Heh!! I am sure someone else must stock these which can be brought in vastly smaller quantities. The colourburst were peanuts for a bag of 50.

[ataridns]

1 hour ago, TZJB said:

Your Lab PSU at 5.2V should read the same at J7 unless the connecting lead has a bad conductor? Also C2 should not logically be at a larger potential than J7 as it is fed from J7. Please re-check the J7 voltage reading.

Sory to correct you but the positive power in, goes to switch and then to C2 and C3 and through L1 (which is 10 Ohms!!! 820 µH,  ±10%) to J7 and to the possitive of the near axle cap. 

So L1 = 10 Ohms thats why "The Voltage at J7 is 4.73V ,and at C2 and C3 is 4.81"

 

Also my Chinese Lab psu when the mb switch is off displays 5,2v and indeed it is 5,19 (fluke mmeter) but when I turn on the atari mb switch although the display is the same 5,2v in board there is 4,8 V (mmeter Fluke at p.plug inputs)

So all my numbers are correct. 

 

1 hour ago, TZJB said:

Also sorry for my typo for GTIA pin 29 FØ0 OUT. I only had one glasss of wine yesterday 😁.

 

You must not do such mistakes. After the 3rd glass you are Ok! 

 

You convince me to find real crystals and not the si5351 i2c. I will search and in local market maybe I spot something.

Edited March 20 by ataridns

[ataridns]

Searching the web I found a very nice very old page about Freddie:  

 

Thanks to Pasiu/SSG at https://hardware.atari8.info/freddie.php 

 

Translated to English is here

 

Also a very nice pic about freddie from the same site in Windows98!!! old memories...

 

Edited March 20 by ataridns

[TZJB]

58 minutes ago, ataridns said:

Sory to correct you but the positive power in, goes to switch and then to C2 and C3 and through L1 (which is 10 Ohms!!! 820 µH,  ±10%) to J7 and to the possitive of the near axle cap. 

So L1 = 10 Ohms thats why "The Voltage at J7 is 4.73V ,and at C2 and C3 is 4.81"

 

Also my Chinese Lab psu when the mb switch is off displays 5,2v and indeed it is 5,19 (fluke mmeter) but when I turn on the atari mb switch although the display is the same 5,2v in board there is 4,8 V (mmeter Fluke at p.plug inputs)

So all my numbers are correct. 

 

You must not do such mistakes. After the 3rd glass you are Ok! 

 

You convince me to find real crystals and not the si5351 i2c. I will search and in local market maybe I spot something.

 

No problem. It looks like I need to check my 800XLF as I am not fully understanding how your connector J7, which is the 7 pin DIN power supply input jack, is not directly connected to your PSU as per the schematic.

 

@Beeblebrox are you making any sense of this?

 

I do try not to get too inebriated so 3 glasses of wine are only for my Birthday 🤪.

 

I hope that your search for the crystals is successful.

 

1 hour ago, ataridns said:

Searching the web I found a very nice very old page about Freddie:  

 

Thanks to Pasiu/SSG at https://hardware.atari8.info/freddie.php 

 

Translated to English is here

 

Also a very nice pic about freddie from the same site in Windows98!!! old memories...

 

 

Thanks for the FREDDIE links.

 

 

[TZJB]

Hi @ataridns.

 

I finally hooked up my 800XLF and took some voltage readings and they are as I expected.

 

This is using a Meanwell GST18A05 5V 3A PSU adapted to 7 pin DIN, and a Fluke77 multimeter:-

 

J7 (DIN INPUT)- 5.00V

C2 & C3 - 5.00V

FREDDIE - 4.99V

ANTIC - 4.98V

SALLY - 4.98V

GTIA - 4.98V

POKEY - 4.95V

PIA - 4.99V

OS ROM - 4.97V

BASIC - 4.97V

DRAM - 4.90V

 

Incidentally, this 800XLF is one where I have replaced all of the electolytic capacitors as I had them to hand.

 

[ataridns]

Dear friends,

Time is of the essence, and many things are awaiting me in real life. I waited for friends from the local market to find the crystals, but nobody could find them.

They told me they are ancient! Like me, hehehe...

 

So today, I ordered the critical crystal 14,187 (20 pieces, costing about 17 euros mostly for shipping) from a business store in Poland using a business account. Now, I am waiting again.

This is the most boring part of the repairs, unfortunately.

 

Additionally, I must change the three axial caps in the power input part of the board. I will also try using a good quality PSU (5V 3A or 5A) to ensure stability because 4.7V in C2 is not ideal when providing 5.3 volts at 2A in the input socket.

 

I'm unsure if I should check all the DRAMs now by making sockets and changing them with the good ones that I have plenty of. I will prioritize solving the the crystal and power problems first and then assess the situation.

 

On 3/24/2024 at 6:12 PM, TZJB said:

This is using a Meanwell GST18A05 5V 3A PSU adapted to 7 pin DIN, and a Fluke77 multimeter:-

 

J7 (DIN INPUT)- 5.00V

C2 & C3 - 5.00V

FREDDIE - 4.99V

ANTIC - 4.98V

SALLY - 4.98V

GTIA - 4.98V

POKEY - 4.95V

PIA - 4.99V

OS ROM - 4.97V

BASIC - 4.97V

DRAM - 4.90V

 

TZJB, well done! You have a very good power input! What caps did you put? Are they of the same characteristics as the factory ones, and what brands and ESR?

I didn't manage to make a valid caps order, but I will make it ASAP.

 

Edited March 28 by ataridns

[TZJB]

On 3/28/2024 at 9:01 PM, ataridns said:

Dear friends,

Time is of the essence, and many things are awaiting me in real life. I waited for friends from the local market to find the crystals, but nobody could find them.

They told me they are ancient! Like me, hehehe...

 

So today, I ordered the critical crystal 14,187 (20 pieces, costing about 17 euros mostly for shipping) from a business store in Poland using a business account. Now, I am waiting again.

This is the most boring part of the repairs, unfortunately.

 

Additionally, I must change the three axial caps in the power input part of the board. I will also try using a good quality PSU (5V 3A or 5A) to ensure stability because 4.7V in C2 is not ideal when providing 5.3 volts at 2A in the input socket.

 

I'm unsure if I should check all the DRAMs now by making sockets and changing them with the good ones that I have plenty of. I will prioritize solving the the crystal and power problems first and then assess the situation.

 

TZJB, well done! You have a very good power input! What caps did you put? Are they of the same characteristics as the factory ones, and what brands and ESR?

I didn't manage to make a valid caps order, but I will make it ASAP.

 

 

I am glad that you have sourced a 14 MHz crystal and some spares....

 

Regarding DRAM, you might be lucky and not need to change them. I was not aware of the history of my 800XLF and did wonder if damage was caused by over-voltage as the CPU had also expired.

 

The electrolytic capacitors I used were Panasonic FR series for C13 & C14 470uF 16V as I use them for switched mode PSU repairs, however low ESR is not required for a normal DC voltage, so I replaced the others with standard 10uF and 22uF 85C 35V radial capacitors. Axial capacitors tend to be more expensive for some reason, and the computer cannot tell the difference!

 

[ataridns]

 

7 hours ago, TZJB said:

The electrolytic capacitors I used were Panasonic FR series for C13 & C14 470uF 16V as I use them for switched mode PSU repairs, however low ESR is not required for a normal DC voltage, so I replaced the others with standard 10uF and 22uF 85C 35V radial capacitors. Axial capacitors tend to be more expensive for some reason, and the computer cannot tell the difference!

 

Thank you TZJB for the feedback!

- Finally, I also ordered new Panasonic caps and 10 Crystals 4.43361875 to experiment with, from Mouser.

- Additionally, I found similar crystals in China and ordered a batch for comparison at a very low price.I will check and measure them all, when they arrive.

- I must also find a trustworthy PSU to ensure safety when powering on.

 

* The Polish seller is taking too much time to ship the critical 14MHz crystal, and I can't do anything without it. If they do not ship it soon, I don't know what to do next.

Edited March 30 by ataridns

[ataridns]

Crystals were replaced, and every frequency at the involved chips is now okay, as TZJB very nicely explained.

I also changed all capacitors except for the three non-polar ones (C19, C20, C22).

Additionally, L3 was removed, but now I’m facing a black screen.

Occasionally, I see a screen with horizontal color bars, but this is very rare.

The voltage levels have improved slightly to 4.83V in FREDDIE and 4.85V at the input.

 

Now, assuming that the volts, reset, and frequencies are okay, I need to search for signals.

I suspect a bad ROM, but I tried using a Super Salt cartridge with no results.

 

* when powering on, for milliseconds, a red screen appears and then black. 

 

 

 

 

 

[ataridns]

I attached the color bars image , notice that when I adjust the white variable resistor pot, the colors are changing and getting into BW.