11 replies to this topic

[cityside75]

I know this is the place to come for the definitive Jaguar info - I hope someone can help me.

First some background: I bought this Jaguar untested in a big cheap lot today off CL. I saw rust on the cartridge port screws when I looked it over at the sale, so I was not too optimstic, but it was part of a big lot so I just took it. Sure enough, it's definitely been in water and has a lot of water damage and rust. After failed attempts to power it on, I opened it up...it looks like someone punched the top and broke the switch...the internal switch is completely trashed.For the heck of it, I stuck my needlenose pliers in the switch to join the contacts and it actually powered on.

Encouraged, I cleaned it up very well and checked it over. Nothing is burnt out on it, and after cleaning it up the board doesn't look TOO bad, the damage appears to be isolated to the switch with no other board damage. I was able to get most of the rust cleaned up and it was just surface rust. So I put it back together and plugged in a game, attaching it to my TV via RF. I got immediate boot-up to the game, but no sound. There's also no sound at the Jaguar title screen (it's supposed to roar and play a song I believe). Mine is silent.

I checked all the basic things first, like switching between ch 3&4 and switching the Jaguar's RF Out. I turned the TV all the way up and I don't hear even the faintest sound. I removed and opened up the RF modulator on the Jag but couldn't find anything wrong with it. I also found a pinout of the AV pins and used some alligator clips to try and pick up any sound off the AV connector and was not able to pick up anything.

I've read that attaching the wrong power supply can kill power modulators. This Jag doesn't show any signs of that as it powers up and looks great, but is silent. I know that the audio section has its own separate power modulator. Can I test this? The sites I read said that when it dies it often distorts or melts on top. Mine shows no damage. There are what appear to be Test Points on the board that I've been checking with my meter. I get voltage at every one I've found except for TP6 which is directly connected to the audio power modulator. There is almost no info about Jaguar repairs on the internet so I'm totally shooting in the dark here. Am I chasing my tail? Is there any way to save this thing???

Edited by cityside75, Wed Apr 6, 2011 9:10 PM.

[Jag_Slave]

Hopefully an expert here can help you soon, I hope you can salvage it

[Sauron]

I'm assuming that you don't have composite A/V cables to connect the Jag to your TV. If you managed to pick up A/V cables on eBay or through another source, I'd suggest using those cables instead of RF. The Jag's RF output is awful, and A/V cables would be a very wise investment if you're really wanting a working Jaguar. If you're adept at hacking cables and connectors, you could alternately try making your own. I'll have to look around to see if there is any info on what to use for the connector.

How exactly did you try picking up sound with the alligator clips? Were you splicing them into the RF, or trying to output through the audio input of the A/V input on your TV?

[Stephen Moss]

If I recall you can obtain a copy of the Jaguar schematic diagram from Matthias Domins website if you don't already have it. I can't recall the address right now but I am sure a link to it was posted on the forum not long ago so try doing a search.

Yes connecting the wrong power supply to the Jag can kill the voltage regulators however it usually kills both and the fact that the main Jag boots make that unlikely, though not impossible.

I suspect the reason you may not be having sound it that the power switch is Double pole double Throw and that you plier solution to fixing the switch is only making contact with one set of terminals.
If this is the case it can be easily checked as the voltage regulator for the Audio circuitry is REG1 (an LM78L05ACM), you should have roughly +9V DC going to pin 8, +5V DC coming out of pin 1 (TP6) and all the other pins should be connected to ground (0V). So if you do not have +9V DC going in then my assumption is correct, if you do have +9 DC going in but nothing comming out then it could be either...
1 - the regulator
2 - short circuit C24 or C35 - regulator will probably get very hot very quickly
3 - open curcuit R63

[cityside75]

Great info so far, thanks!

Regarding my alligator clips - I found the pins on the A/V out that carried line level left audio, right audio and ground. I then clipped to left audio and ground, while clipping the other side of the clips to a standard headphone jack (clipping ground to the bottom segment of the headphone jack and left audio to the top segment of the jack. This jack connects to the line input of an old boombox that should amplify the line level audio. It's not perfect, but it should have given me some sound but I got nothing after multiple tries and double checking all connections.

Stephen - I think you may be onto something...I checked voltage on every pin of REG1 yesterday and I don't believe I got juice on any of them. I'm going to double check this today. So if I want to investigate this further, should I be jumpering specific pins of the power switch together? I'm ready to just completely remove that switch since it's way beyond repair. If I can rig up some jumper wires to test it that would be great. I did find the schematics, so maybe the answer is there.

So, is this internal switch a standard unit that I can replace at Radio Shack, Fry's or online? Anyone have a part number or other info?

Thanks again for everything so far!

Edited by cityside75, Thu Apr 7, 2011 7:25 AM.

[Chuplayer]

cityside75, on Thu Apr 7, 2011 7:21 AM, said:

Great info so far, thanks!

Regarding my alligator clips - I found the pins on the A/V out that carried line level left audio, right audio and ground.

Um... Are you shorting out the pins by doing that?

http://www.gamesx.co...nouts/jagav.htm

I used the above when I had to rebuild an AV cable, and it is correct for at least composite video and the two stereo audio channels.

[cityside75]

Chuplayer, on Thu Apr 7, 2011 3:23 PM, said:

cityside75, on Thu Apr 7, 2011 7:21 AM, said:

Great info so far, thanks!

Regarding my alligator clips - I found the pins on the A/V out that carried line level left audio, right audio and ground.

Um... Are you shorting out the pins by doing that?

http://www.gamesx.co...nouts/jagav.htm

I used the above when I had to rebuild an AV cable, and it is correct for at least composite video and the two stereo audio channels.

I don't think so, I mainly was just touching the two clips to pins 1A and 3A (I located the same wiring diagram that you linked to) with the amplifier on listening for any sound at all. The other ends were clipped to left audio and ground on the headphone jack. I could be wrong, but it seems to me I should have heard at least a bit of sound doing this, but I never heard anything.

I'm still interested to know what pins of SW1 I should jumper to get power to the sound section of the motherboard if anyone knows. If I could establish that it works (which the signs seem to point that way now) then I'll just focus on rebuilding the switch and be on my way to resucitating this poor sad Jag back to life. I'll probably just experiment if I don't get a response here...I assume that it's only a small amount of power being run through the switch, at least that's usually the case.

[Chuplayer]

cityside75, on Thu Apr 7, 2011 9:03 PM, said:

Chuplayer, on Thu Apr 7, 2011 3:23 PM, said:

cityside75, on Thu Apr 7, 2011 7:21 AM, said:

Great info so far, thanks!

Regarding my alligator clips - I found the pins on the A/V out that carried line level left audio, right audio and ground.

Um... Are you shorting out the pins by doing that?

http://www.gamesx.co...nouts/jagav.htm

I used the above when I had to rebuild an AV cable, and it is correct for at least composite video and the two stereo audio channels.

I don't think so, I mainly was just touching the two clips to pins 1A and 3A (I located the same wiring diagram that you linked to) with the amplifier on listening for any sound at all. The other ends were clipped to left audio and ground on the headphone jack. I could be wrong, but it seems to me I should have heard at least a bit of sound doing this, but I never heard anything.

I'm still interested to know what pins of SW1 I should jumper to get power to the sound section of the motherboard if anyone knows. If I could establish that it works (which the signs seem to point that way now) then I'll just focus on rebuilding the switch and be on my way to resucitating this poor sad Jag back to life. I'll probably just experiment if I don't get a response here...I assume that it's only a small amount of power being run through the switch, at least that's usually the case.

Alligator clips aren't dual-conducting. At least, none that I've ever seen. But even if they were, based on what I'm understanding, you're connecting the audio channels to each other and their respective grounds to each other.

[cityside75]

I don't see how I would have crossed the audio channels when I only touched the clips to pins 1A and 3A of the a/v output but regardless, I think the issue at hand for this unit is that there is no current running to REG1 which I believe is related to the double pole/double throw switch. Without voltage at REG1 the audio SHOULDN'T be working from what I understand. Anyway, I'll have more time to work on the Jag tonight, so I'll update this thread if I make any progress.

[cityside75]

After studying the schematic on my lunch (I work from home) I determined that pins 5 & 6 of SW1 had to be joined for the sound system to get power. I jumpered them together real quick and fired it up and we have SOUND!!!

So everything is now functioning correctly. I just need to get a switch, but I may temporarily jumper the proper pins together and make it a "power on at plug in" system for the time being. Thanks again for everyone's help, especially Stephen who nailed it immediately. Much appreciated!

[Stephen Moss]

cityside75, on Fri Apr 8, 2011 7:15 AM, said:

I don't see how I would have crossed the audio channels when I only touched the clips to pins 1A and 3A of the a/v output but regardless,

I think he was a little confused as I am as to how you could attach a croc clip (presumably to the PCB) without connecting to both sides, thus shorting the top and bottom connections together.
I would not put too much faith in that page which is linked to, although most of the pin functions match a few do not tie up with the schematic/TechRef.

cityside75, on Fri Apr 8, 2011 11:02 AM, said:

After studying the schematic on my lunch (I work from home) I determined that pins 5 & 6 of SW1 had to be joined for the sound system to get power. I jumpered them together real quick and fired it up and we have SOUND!!!

So everything is now functioning correctly. I just need to get a switch, but I may temporarily jumper the proper pins together and make it a "power on at plug in" system for the time being. Thanks again for everyone's help, especially Stephen who nailed it immediately. Much appreciated!

I did not have time the check back over the weekend, glad you got it working.
If you have not thrown it out you should be able to find either a manufactures name or part number on the switch that will allow you to look for a direct replacement, but any DPDT pcb mounting switch of the same size will probably work. If you have a local store that sells such things you could always take the switch into them as ask them for if they have a replacement and they could probably identify it for you.

[cityside75]

Stephen Moss, on Mon Apr 11, 2011 2:21 AM, said:

cityside75, on Fri Apr 8, 2011 7:15 AM, said:

I don't see how I would have crossed the audio channels when I only touched the clips to pins 1A and 3A of the a/v output but regardless,

I think he was a little confused as I am as to how you could attach a croc clip (presumably to the PCB) without connecting to both sides, thus shorting the top and bottom connections together.
I would not put too much faith in that page which is linked to, although most of the pin functions match a few do not tie up with the schematic/TechRef.

cityside75, on Fri Apr 8, 2011 11:02 AM, said:

After studying the schematic on my lunch (I work from home) I determined that pins 5 & 6 of SW1 had to be joined for the sound system to get power. I jumpered them together real quick and fired it up and we have SOUND!!!

So everything is now functioning correctly. I just need to get a switch, but I may temporarily jumper the proper pins together and make it a "power on at plug in" system for the time being. Thanks again for everyone's help, especially Stephen who nailed it immediately. Much appreciated!

I did not have time the check back over the weekend, glad you got it working.
If you have not thrown it out you should be able to find either a manufactures name or part number on the switch that will allow you to look for a direct replacement, but any DPDT pcb mounting switch of the same size will probably work. If you have a local store that sells such things you could always take the switch into them as ask them for if they have a replacement and they could probably identify it for you.

Just a simple piece of cardboard slipped between the clip and bottom pins was used to insulate the connection from shorting the top and bottom together...nothing fancy. Just to be sure, I unclipped completely from the PCB and just touched the tips to the appropriate pins, with the other ends still clipped to the jack as I described.

Good call on the switch, I have a local store that may be able to match a part number if I can locate one. Thanks again!