kaboom no kaboom

[Superduper]

Hmm. Looks like a similar routing system to many of the Sony boomboxes, although on the Sony, the second belt goes to a different pulley. If the motor pinion pulley looks the same, I'll bet this is a dual belt system. Otherwise, it seems weird that it would have a redundant unused pulley groove.

 

[blah blah]

yep the motor pinion pulley has the same groove....

 

[Fatdog]

Hey guys, I found the service manual for the RV-DP100BK.

http://elektrotanya.com/jvc_rv-dp100bk.pdf/download.cgi

It only shows a single capstan belt, but it does show how it should be belted.

 

[blah blah]

your the map fatdog! i wish i would have looked at this 2 minutes ago cause i just bought one

thanks for finding it none the less

 

[Fatdog]

i wish i would have looked at this 2 minutes ago cause i just bought one

thanks for finding it none the less

Darn! I wasn't fast enough. Sorry, blah blah. Maybe there is still time to cancel the order.

 

[blah blah]

No worries Fatdog! they already sent it to me, i will have a high quality repo to be able to share. i have the sinking feeling though this box may be my new giant paper weight anyway. i am pretty stumped. belt is on correct. just will not shift in any function. i thought i had it with the broken caps but something else is the problem....probably the main pcb. arrgh

 

[Fatdog]

I wonder if the corrosion completely destroyed a trace somewhere? Well, I guess there's only one way to find out. Good luck with it.

 

[ohboy]

Hey guys...
got off work early and tearing into my Kaboom now...
Hay Blah Blah... did you check the fuses in the rear of the radio yet? if you pull off the rear vebnting... there are two fuses
you may want to check out first.... I pulled them out one at a time... and if you pull just the bottom one... it does exactly what you are describing..... it could be as simple as that....
I would still check the trace on that board though... even if that is the remedy....

I will let you know more in a few....

Gordie... I hope you are enjoying that kaboom as much as I do.... and I hope we can get Blah Blahs fixed too

 

[ohboy]

Actually there is a third fuse as well. there in the back...sorry....

 

[blah blah]

thanks ohboy, all three fuses are good. i cannot find a bad trace either where the board was damaged so far... there are some tiny capacitors and resistors that look iffy but can't figure out how to measure to check. i will post a pic if i can, they are really really tiny :'-( and i am not sure what if anything they should read....

but i can take it apart and re-assemble the entire kaboom in about five minutes

 

[ohboy]

[quote="

but i can take it apart and re-assemble the entire kaboom in about five minutes

 

[monchito]

wow that board did not look to good

 

[blah blah]

yea its kinda pissing me off. so far i found no bad traces but it is wacked out in the worst spot where its hard to tell whats what

i am making an insane diagram that i will post hoping for more help. on a better note i have a killer manual for it if anyone gets needy.

 

[monchito]

i still have to do mine

 

[blah blah]

this is how insane it's driving me (see below). Lets see how insane you guys are for looking if your really a schematics freak i will email it, it ,might be too small to see!

there seems to be continuity everywhere the red lines appear. i also checked on all the traces that were not near the damage. the yellow lines are where i cannot get any continuity. the traces seem fine, just cannot get it to get a reading and not sure what to do with the tiny rectangular resistors. its funny as one is way off the beaten path and seems totally undamaged. and those look impossible to replace since i cannot even read them.

any wisdom beside spend more money for better boxes?

 

[Superduper]

this is how insane it's driving me (see below). Lets see how insane you guys are for looking if your really a schematics freak i will email it, it ,might be too small to see!

there seems to be continuity everywhere the red lines appear. i also checked on all the traces that were not near the damage. the yellow lines are where i cannot get any continuity. the traces seem fine, just cannot get it to get a reading and not sure what to do with the tiny rectangular resistors. its funny as one is way off the beaten path and seems totally undamaged. and those look impossible to replace since i cannot even read them.

any wisdom beside spend more money for better boxes?
[ Image ]

With tweezers and a small tip soldering iron, those little resistors can be replaced. However, I doubt that they would all be bad. The values are usually stamped right on the resistor but you might need a magnifying glass. No color bar codes, just numbers. Do an internet search for values of SMD resistors to help you identify them. If you do believe they are bad, and you can't determine the value, then any service manual worth it's salt should steer you in the right direction.

As for not getting continuity where an obvious trace exists, that might or might not be a problem. As I stated earlier, most modern PCB's are conformal coated and the coating is an insulator. You usually need to press hard to pierce the coating or heat reflow the solder, which will burn off the coating. If you are confident that it really is a trace, and you really aren't getting any continuity, then it might be a cold solder joint, corroded, or the trace is broken. Don't worry that you can't see the fracture. I've found many broken traces before that wasn't visible to the naked eye. Bypassing the trace usually fixes the problem. However, make certain (use service manual as guide) to ensure that it is indeed a true trace and that you won't inadvertently short something that isn't intended to have continuity. If the JVC manual you have is consistent with older JVC service manuals, then it should be comprehensive and include almost everything you need to determine the contents of that PCB.

Hang in there and take frequent breaks if necessary.

Norm.

 

[oldskool69]

...Hang in there and take frequent breaks if necessary...

This is the best advice any of us could could give. No matter how good your vision is your eyes will get tired looking at tiny components. Plus, we all get a little frustrated so it's good to even let it go for a day and regroup your thoughts. What I have found that works well also is taking notes of progress. This way I don't or can back track if neccessary. Also my father is a retired technician with over 45 years experience and he taught me as a young lad to take my time and also bought me one of these...

Lighted articulating magnifying glass. If you don't have one, get one. A world of difference. Trust me.

 

[blah blah]

Thanks guys, i will indeed take frequent breaks. i am for sure getting the light magnifying glass, that's an awesome idea.
hopefully i will have something positive to update at some point. thanks for all the advice as usual.

 

[blah blah]

UPDATE: Never mind. I installed already but had no effect...

Got 2 quick questions:

1. Are these caps the same, I assume they are. The black one is the original but has one rusted leg. Wondering if rust might have crept up and be causing the problem even though unit powered up? It came off the ac/dc-outlet trace next to the heat sink on my damaged board.

So should I replace with the blue? if so, should i install with bands in same alignment since it is + -?
I know how the old one was aligned.

2. The solder on this board is cold! I cannot even get it to release where the damage to the board occurred. I am not blistering the board but am afraid of damaging components. Just keep trying until it goes or?

I am gonna get a book

 

[redbenjoe]

hey BB --
this has been brave of you to hang in there

even if you dont get it all fixed --
i think you have a win/win deal going --

because these are not ultra rare nor very expensive-
so - if you end up winning a better bp100 --

you will have this parts box -
and lots of know-how