CDTV no display issue

[jrtolson]

hi all.

my cdtv will not display any picture from either RF/Composite or RGB monitor out...

i would really like to fix this machine it is been broken since the early 90's.. it works as the sound of games and cd's can be heard.

to aid any responce i have posted a video on youtube here:

http://www.youtube.com/watch?v=3EhfLVp279I

i have read about the HY1 Hybrid been a possible cause, but i have doubts on that in this case (as it would effect only colour of the image i believe, see link), i personally think it is just the video board itself..

http://www.amicue.org/TechStuff/TroubleShootingChart.html

i have seen this site do replacements: http://www.vesalia.de/e_cd1321.htm

but they out of stock.. (i have emailed them)

i have read somewhere about soldering a bridge on the pins that go to the video board to bypass it but im not sure on how to go about this? if anyone could advise?

http://www.hardwarebook.info/CDTV_Video_Slot

has anyone had this issue and solved it? maybe by simply resoldering some caps? jumping pins? replaceing IC's? or know some guy that has these cards spare by the bucket load? (im no electronics expert lol)

any help would be greatly appreciated thank you :-)

[Castellen]

As there's no RGB video, that suggests something around the Deinse or video hybrid area.

I'd start by checking you have +5V on the +VID line (pin 2 of HY1). If not look at R6 (4.7 Ohms) which may be open circuit.

Also try the obvious of re-seating socketed ICs, though fortunately most of the video stage is soldered in.

The CDTV video section is near identical to an A500, so if required you can also get parts from an old A500 which are usually easy to get.  The actual video schematic for the CDTV is here.

I could repair it for you, although return freight from New Zealand would be getting pricey.

[amiman99]

Try this fix to bypass the video module.

http://www.amiga.org/forums/showthread.php?t=59038&highlight=cdtv

[jrtolson]

i have read thread on bypassing the video module.. even downloaded the pic? but i aint got no idea on how to go about that?

as for checking voltages on certain pins? u mean getting a multimeter, poking an unused ground pad with the black probe and the red probe on a +5 volt pin/s to check for readings?

[jrtolson]

update,

 using a the pin chart i have used the multimeter to test the RGB and sync lines on the video board all seem ok, tho the rgb seems buffered..

i have tested the +5 line from HY1 to rgb port and video connector ground pin all seems ok. aswell rgb from rgb port to video in from mainboard to video card and there is power

so maybe i thought i would start from the beggining, i have ordered a DENISE 8362R8 from amigadeals.. for a fiver.. ill try swapping it out see if that makes a difference?

when it gets delivered lol

[Castellen]

The video module bypass thing essentially involves linking pins on a connector as it suggests in that photo.

A faulty Denise would probably result in the system not booting at all, but it's not as though you've spent a lot of money and there's a small chance that may fix it.  The next logical step is to do a bit of fault tracing but you'll really need an oscilloscope for this, plus know what you're doing.

[arttu80]

i have read thread on bypassing the video module.. even downloaded the pic? but i aint got no idea on how to go about that?

Hi!

Bypassing that module is really simple, if you have some sharp tip soldering iron at your disposal. Just make jumper wires according to picture I posted in my topic. All mentioned pins are soldered in pairs and are located on same row and each pin pair is neighboring to each other. So solder one pin pair at a time and remember to remove video module BEFORE powering up. The ribbon cable I used isn't necessary at all, but it's lot cleaner than just plain jumper wires and I used DIP-switches if I ever connect video module or some expansion in that slot.

Please take a look at more hi-res pic on link below, hope it helps.--->

http://aijaa.com/v.php?i=004399112626.jpg

I even draw simplified jumper "diagram" for ya. Sorry if it appear lame, but it's clearer than water in my toilet!

[jrtolson]

sorry for the lack of update, it took ages to get the Denise chip via post..

well after replacing denise, no change.. still no picture so tinkered with it for a few hours, if i boot from floppy into a game i get a few a couple of very faint screen text but it last only a few seconds and its gone.. it was very hard to catch on camera as it was intermittent

http://www.youtube.com/watch?v=ePX0cHkKcps

i have a very basic powered tester, with it a test the caps on the video board, they take charge and discharge but like i said before im no expert lol

Arttu80 - yes it was your mod i mentioned previosly and thankyou for explaining it furthure to me, i guess simply jumping the connections is ok without buffering? also i noticed aswell as jumping RGB, u jumped Horizontal sync out to bufferd composite sync in? is that needed and or why not jump the vertical sync aswell? ( im asking because normal monitor should be at 15khz anyway, is jumping the sync needed?) :-)

also arttu80, just out of curiosity i noticed the main power in connectors (1 black and red and the other black red yellow orange) at the center of your board are flipped? mine is 4 wires top 2 bottom? yours is reverse? im not sure wot would happen if i reversed mine or if it wrong lol i dunno wot they power?

one last note (u may hear in the video) during floppy based games the sound is very Poppy and crackled even at low volume.. it is not there any other time and cd software sounds fine.. just modules that play? an issue for another time maybe...

any suggestions would be welcome and thanks for the help so far ill look into artt80's solution next chance i get :-)

[psxphill]

you could try hooking your monitor to the digital rgb lines. you'll only get 8 colours but it might give a hint to the problem.

[jrtolson]

bummer :-(



i went to maplins with the intention of getting some 470uf 16v caps but they had none in, so i asked for 35v ones instead thinking they be ok lol



the board will not fit in the slot now :-(

[jrtolson]

another update, Maplins still had none of the caps i needed so i decided just to bypass the video module...



my soldering skills are not great, and yes that is speaker wire lol but...



Viola!!.. im over the moon :-) cheers arttu80 your a star m8 :-)

a few issues remain however, the cd drive only reads discs when it wants to. takes 237 attempts to get simcity going and/or the welcome cd, but once they decide to run the don't stop..

also the sound is distorted on both cd music and normal 4 channel paula sound.. it is ok at low volume or when only one or 2 channels are used, but once it gets loud it gets very distorted kind of like turning a cheap stereo up to loud that the sound breaks up, ill have to youtube it to give u guys an idea i think, but could it be dodgy cap or 2 in the sound stage? any way here is a pic



the black cap looks like just pen to me? anyhow any help would be greatly appreciated, thankyou all :-)

[BinoX]

Both of my CDTVs and my spare motherboard both have black pen on that same capacitor, so I think you're fine there

Not sure with the CD Drive... Have you tried a CD Lens cleaning disc in it? Because it sounds much like what my old stereo was doing not long ago..

[Amiga_CDTV]

a few issues remain however, the cd drive only reads discs when it wants to. takes 237 attempts to get simcity going and/or the welcome cd, but once they decide to run the don't stop..

When you have inserted the caddy, try to press it a bit deeper and down. In my CDTV the caddy doesn't always move all the way thrue and needs a bit of a push to lock to a correct position. Also sometimes the intro screen turns red (meaning the disc cannot be read), even without a disc inserted. I guess there is sensor -switch inside the mech. and cleaning that would improve this.

Video module; you mean the 470 uF 35v cap won't fit because it's too high? If there is enough space, you could try mounting the caps horizontally. Leave long enough "legs" between the cap and the circuit board and bend the cap against the board.

[amigadave]

Does anyone know if CDTV.org is going to make a comeback?  It was a great site for CDTV users and owners.

[jrtolson]

when i get time over the weekend im going strip the cdtv again to ty and dissasemble the cdrom, i could not do that the first time as the fron two screws holding the cd drive and electronics in will no budge for love no money.. so i will have to learn the force and become a jedi to strip it completly without chewing up the screws, but i reckon the lens is probabily dirty..

as for the sound, i downloaded the schematics for the audio section and following the pins from paula the sound goes through one opamp chip (left one in pic) twice (each chip has 4 amps in them) then it and the cd audio goes through the second op amp chip(the right one in pic) once (2 not used) then a tiny cap, a ressistor or 2 then phono jack out. it also looks like the  front panel audio also comes out straight after the second opamp..

so my next action is hook the cdtv up to an amp (my main stereo) and find the channel at fault, also test the fron audio jack to see if thats at fault too, if so it will illiminate the caps/ressistors after opamp 2...

reading some other forums, it could be a power issue, when connect to my logitech active amp i get random pops and load squrks, which could be overvoltage spikes feeding the opamps, so that would be another thing to check maybe?

if the LF347N is at fault, i will then get some more and replace them (seen them for 50 pence each on a website lol)

one question i have tho is if the second opamp only uses 2 amp in it can i just flip the chip over? i know then the vcc +/- will be reversed but apart from that all the other pins are the same? but i don't know if the chip would work in a reverse polarity setup? im no expert lol, just an idiot with an soldering iron :-)

any advise will be greatly appreciated.. thank you :-)