No Sound from PCjr 4863 monitor

Hardware questions and modifications

No Sound from PCjr 4863 monitor

Postby drignor » Mon Mar 27, 2017 7:20 am

Hi folks,

First, thanks to Mike for the add to the forum. It's great to see a community dedicated solely to the woefully underappreciated PCjr. The PCjr was my first computer ever, got it when it was originally released back in 1984. Since then, my original was given away (thanks, dad!) and then ultimately thrown out by the ungrateful recipients. Anywhoo, enough backstory. I just recently came into possession of a new PCjr from a local guy who fixes up old machines and resells them. It didn't come with the monitor, so I had to purchase that separately from a gent in Texas that's been in business since 1983 and has a pretty good stock of used ones. So, I got in touch with him, purchased the monitor and he had it shipped to me in three days. Got it the other day, unpacked it, hooked it up to the jr, and voila! The picture is gorgeous and the monitor is in great shape. However, there is no sound coming from it. I've played with the volume, but nothing. I know there is a signal for the sound coming to it, because when I plug in a pair of headphones (also, the headphone jack appears messed up as well) I can *BARELY* hear the sound that's supposed to be coming through. I say barely, because there is a ton of static and interference noise coming from the jr itself (you can actually *hear* the memory ticking off as it's being checked on the startup screen, as well as noises when the disk drive spins up), and the actual music or sound or whatever is supposed to be playing, is barely audible and you have to really strain to hear it. So, after that long winded description, has anyone had any experience with this kind of problem before? Could it be something as simple as a disconnected wire somewhere or an easily replaceable blown amp? Any help would be appreciated.
drignor
 
Posts: 9
Joined: Sun Mar 26, 2017 12:19 pm

Re: No Sound from PCjr 4863 monitor

Postby Trixter » Mon Mar 27, 2017 12:54 pm

Welcome to the forums! To narrow down the problem, go into the built-in diagnostics by hitting CTRL-ALT-INS after bootup, then navigate to the sound tests and run them. You should hear the "beep" coming from both the PCjr and the monitor, and you should hear the 3-voice tests coming from the monitor only.

If you hear nothing, connect a speaker to the audio output jack of the PCjr, then run the tests again to see if they are different. If they are the same, your PCjr has a problem in the audio output stage. If they are different, then your monitor is the issue and needs to be troubleshot further.

For clarification, the marking on the PCjr monitor is backwards -- you turn the bottom of it to the left to increase the volume. Make sure it is set halfway inbetween both extremes.
You're all insane and trying to steal my magic bag!
Trixter
 
Posts: 508
Joined: Mon Sep 01, 2008 12:00 am
Location: Illinois, USA

Re: No Sound from PCjr 4863 monitor

Postby drignor » Mon Mar 27, 2017 3:42 pm

Hey Trixter,

Thanks for the reply. Yeah, I forgot to mention I did the diagnostics, and I heard the internal speaker with no problem, but nothing from the monitor speaker, except from the headphone jack, but with the same results I listed in the first post. I can hear the scale, but barely over all the interference. And yes, I was aware of the reversed volume, but I tried both extremes just to be safe. I haven't had a chance to test the audio output jack yet. That's going to be my next step. Will any old RCA audio cable do? And if so, can I just hook it up to a regular TV with RCA inputs?
drignor
 
Posts: 9
Joined: Sun Mar 26, 2017 12:19 pm

Re: No Sound from PCjr 4863 monitor

Postby drignor » Mon Mar 27, 2017 4:24 pm

Ok, so I tried hooking the Jr up to my TV with some RCA cables I have lying around, and unfortunately, it looks like the audio output isn't working there either. Crap.
drignor
 
Posts: 9
Joined: Sun Mar 26, 2017 12:19 pm

Re: No Sound from PCjr 4863 monitor

Postby Trixter » Mon Mar 27, 2017 4:43 pm

Sorry to hear that. There may be a broken trace on the motherboard somewhere; it will take continuity testing to find and repair it.
You're all insane and trying to steal my magic bag!
Trixter
 
Posts: 508
Joined: Mon Sep 01, 2008 12:00 am
Location: Illinois, USA


Return to PCjr Hardware

Who is online

Users browsing this forum: No registered users and 1 guest