Problems with Rowe R-90 Jukebox w/ MP3 Adapter Kit (RMC-MP3)

[thedig10]

Hello All. I have owned this Rowe R90 for about 4 years now with no problems until this week. I fired it up a couple days ago and there is no sound. A selection can be made and the lights will begin flashing as though a song is playing. I am puzzled how this could abruptly happen.

The MP3 adapter kit installed in this jukebox can be seen here (RMC-MP3 model):

http://www.cdadapter.com/download/rmc-mp3.pdf

When I plug/unplug the jukebox, I get a pop from the speakers. This should indicate that the amp & speakers are good to go, right? The next thing I tried was playing music from my iPhone through the jukebox via 3.5mm headphone jack. The headphone jack runs through the "Passive Inverse RIAA equalization filter", seen in the link above, to the phono input on the jukebox. Still no sound.

I will be the first to admit I don’t know much about electronics or audio equipment, so this one is way out of my league. Having trouble finding someone in my area (Kansas City) who will come look at it. The couple people I have contacted seem scared away by the fact it has been adapted to play from a hard drive. I have tried contacting both CDadapter and Data Sync Engineering, but have not heard back to date. I have verified that all songs on the hard drive are still

At any rate, it looks like this message board could be a good resource for troubleshooting. Is there anything a novice like myself can do to isolate the problem? Have tried re-securing all wire connectors.

Thanks in advance for your help. This jukebox has talked me through some tough times. Need to get her back to health!

[Ken Layton]

You should telephone the cd adapter folks. They know the most about your setup.

[thedig10]

Ken - Thanks for the prompt response. I talked with Data Sync Engineering yesterday evening on the phone (the maker of the adapter). The gentleman there was very helpful, and we went through several steps to confirm the adapter is working properly. He seems to think there is a problem with my amp.

Reasons:
1) Heat sink is hot to touch (even if the jbox is off, but still plugged in)
2) If I unplug my phono input and place my finger on the pins, I get no feedback from the speakers.

However, when I plug-in the amp power supply, I do get a pop from my speakers.

Before I replace the amp, I would like to be 99% sure that it will resolve the problem. Any thoughts? What could have caused my amp to just stop working one day?

Thanks!

[lilshawn]

if your amp is hot. i'd suspect a speaker wiring issue (something shorted)

check your wires where they attach to the amp and speakers for any stray scraggler wire strands touching other terminals or metal ground.

you would have to disassemble the amp but repairing it isn't too hard. i wouldn't go so far as replacing the whole thing unless you where no good at fixing things.

[thedig10]

Update: I replaced all four fuses in the amp. One was undoubtedly blown. When I reinstalled the amp to test, there was a flash upon plugging it in. I pulled the amp back out and the same fuse (new) had blown. In talking with a couple people, they think it could be a bad transistor. They say this was shorting out and causing the heat sink to get hot.

Thinking of replacing the amp as a whole instead of trying to mess w/ switching out the transistors.

[lilshawn]

very common. If the output of the amp gets shorted then the transistors blow, the next thing in line is the fuses. the transistors fail shorted so as soon as you power it up with new fuses ZAP the fuse blows again.

you should be able to replace the transistors and the fuses and you should be back up and running.

please note: you must replace the transistors in pairs. There is an NPN and a PNP transistor for each channel of the amp. you can tell the offending channel by where the fuse blows.

if it's the top pre-amp board that the fuse is blown on, replace the top 2 transistors on the heatsink...if it's the bottom pre-amp board it's the bottom 2.

all you do is unscrew the 2 screws on the transistor an pull out the transistor (no soldering required.) be sure to carefully remove the glass insulator sheet off the old one. clean up the grease and put some new stuff on the new transistor and the glass sheet. (so you have a transistor/grease/glass sheet/grease sandwich) and then pop it back in. MAKE sure you don't mix up the transistors. DO NOT FORGET THE GLASS SHEET! this insulates the transistor from ground...without it they will blow the second you plug it in.

the holder under the heatsink can be a bit of a bugger. it can push away and make inserting the new transistor difficult. just use a long screwdriver to hold the holder in place while you push the transistor into the holder. the screws will do the rest.

[thedig10]

I've found a replacement amp for $70.00, tested and working. I am thinking of going this route, as opposed to replacing the output transistors. I'm a novice when it comes to this stuff, so replacing the transistors myself could be bad news.

[lilshawn]

well, hold on the the old amp, you may need parts in the future. can't hurt to have spare parts. be sure to put a tag or something on it describing the problem so when you look at it 3 years from now you aren't like "uhhh....what was broken again"

while you wait, disconnect the speakers wires off the tranformer block and test them with a meter... you should have no less than 4 ohms between the black/purple and no less than 4 ohms between the black/pink wires (i belive those are the colors)

if you have one that reads low (like 2 ohms) you may have a speaker issue.

I had an amp pop at a location on me (CD100E basically the same amp)...went and swapped it... good thing i checked the speaker lines - one was like 6 ohms the other was 2 ohms. whaaa? started tracing back through the crossover and finally to the subs. one of the subs was a dead short (zero ohms) found out one of the subs had the positive and negative plugged onto the same terminal from the factory (has weird 2 tabbed terminal) FOR THE LAST 17 YEARS...nobody had ever cranked up the volume enough to load up the amp and the remaining 2 speakers provided enough load to keep it from dying right away. 

properly connected the sub and fired it up...sounds better than ever.

[thedig10]

Our of curiosity, what causes an output transistor to go bad? Am I resolving the underlying problem if I replace the amp?

[lilshawn]

i would say no. there is a reason for the transistor to go shorted. Extended high volume use IE - overheating or an electical problem IE - power surge or shorted output

[thedig10]

Another thing to note: On the main power supply, there are 3 red LED's, each of which are lit. Anyone know what these are?

[lilshawn]

they are to let you know those voltages are present. If a fuse has blown in the supply, the light will be out.

It's just cause the supply is a PITA to pull out just to check the fuses...so they put lights there so at a quick glance you can tell the power supply is good (in theory)

[thedig10]

Thanks for all the replies on this topic.

Regarding wiring of speakers, here is the current set-up (it was wired like this when I purchased the jukebox). There are 5 wires coming from within the transformer block (Black, Purple, Pink, Red, Brown). They are wired as follows:

Left Channel:
E4 - Purple

Right Channel:
E1 - Black
E4 - Pink

The Brown and Red wires are not attached to a post, but rather taped together.

I lost my left channel about a month before my entire sound was lost. Do the speakers appear to be wired correctly? The j/box was also wired for external speakers, but I removed this wiring recently as they were not connected to any speakers.

Thanks

[ami-man]

Hello thedig10,

Sorry I do not know your name.

For maximum output connect the Pink & Violet wires to E6 left and right.

The red and brown are usually connected to E4 letft & right, above the amplifier compartment lid you will see the various connections, two are marked up extension speakers, these are the other ends of the red & brown wires.

Regards
Alan

Alan Hood

ami-man
UK