zoom 9002 troubles.can anyone help me?

Posted by janP on Mon, 04/28/03 - 05:15:16.
In Reply to Zoom Effects

i have a problem with zoom9002: NO SOUND!! it looks like it' s ok with the output, but input signal is mute!! has anyone a solution for this problem? or at least the device schematics?
thanksalot evryone!!!!
j.p.

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Re: zoom 9002 troubles.can anyone help me?

I have posted all my links and information along with pictures of a ZOOM 9002 repair, the website is: http://home.comcast.net/~mmph/Zoom/Zoom_9002_repair.html

Hope the pictures are helpful to others.

-Mark

Same problem, different sympthoms

It first it came as it had to warm up, I would turn it on, no sound, after a while it began as an engine of an old car: ta ta ta ta tatatata, till, after another while, it finally worked. (sorry about the example). It was a matter of time. But it seems that time has run out, and now I have mix in, metro and tune but nothing else. I've changed the three first caps: one 10mF and two 47. It still does't work. I´ll try the last 47mF and the 7660, see if it does the trick. I´ll tell you. Did or does someone have the same symthoms?
thanx, bye

Re: zoom 9002 troubles.can anyone help me?

: i have a problem with zoom9002: NO SOUND!!

Same problem. Can anybody help me too?
I've found this, but do not understand a lot of eletronic devices:
- The 9002 has a single battery, but the preamplifiers run with dual (+/-)
voltage supplies. The negative supply is made with ICL7660 charge pump.
One of the electrolytic capacitors of the charge pump was failed, and so
the negative supply was not present. I changed all the capacitors around
ICL7660, and after that everything has worked well (this happened ~1 year ago).
I have no pictures to show where these parts are located, but if I remember correct,
the ICL7660 was easily identified, something like "7660" was written on the IC chip.
The failed capacitors were silver colored "cans" in the vicinity of the 7660. -

STe

9002 failure

hello guys.

i been used the 9002 with an adaptation from a motorola´s cellular batery (the original one was dead), but one day i used it until batery deads.

next time i tryed to use it, the unit does not sound until it "warms" it starts sound like an oscilator starts working at the highest frecuecy then sound apears, ( it tooks near 8 minutes) then left chanel sounds dim than right and the 3rd slide in editing mode does not work.

with the frecuent use the problem with the "osscilator" become fade by itself an no problem aobut it anymore.

about the dim channel and the slider that does not work any idea what can be?

tanks a lot

Heeeelp me: hiss after repair

Hi, i repaired my Zoom 9002, sound is present but I feel alwais a hiss.Initially I have thought that the tuner had been activated, but was not the tuner. Can anyone help me ?
Thanks!!

Re: zoom 9002 troubles.can anyone help me?

Same problem with mine. No output other than metro and tuning tone which are a bit weak and off-center in the stereo field. Have opened the unit and now doing the testing and looking for parts sources. I'm amazed that nobody has come up with a schematic so far. If anybody has any more 9002 info or circuit details, etc. please email me? Thanks and best of luck to you 9002 users.

Re: zoom 9002 troubles.can anyone help me?

Okay, I just repaired my third one and this time it was the 7660 IC chip. I tried the caps first and that didn't do it so I bought a 7660 from Digikey.com for less than a dollar and put that in. Now this one is working too. I found that testing the voltage on the chip before repairing had the same symptom (no -5v between pin 3 and 8) regardless of a bad capacitor or bad IC7660.

I only know for sure that the end 10mF cap is the charge cap but the next two 47mF caps may be part of this charge circuit as well. Any way you look at it, it costs less than $5 to change out the caps and IC. Hope this helps.

Correction of pin numbers from preceeding post

: Okay, I just repaired my third one and this time it was the 7660 IC chip. I tried the caps first and that didn't do it so I bought a 7660 from Digikey.com for less than a dollar and put that in. Now this one is working too. I found that testing the voltage on the chip before repairing had the same symptom (no -5v between pin 3&5) regardless of a bad capacitor or bad IC7660.

: I only know for sure that the end 10mF cap is the charge cap but the next two 47mF caps may be part of this charge circuit as well. Any way you look at it, it costs less than $5 to change out the caps and IC. Hope this helps.

IC7660 diagram:
http://www.national.com/ds/LM/LMC7660.pdf

More repair tips and new batteries available

Here are some more repair tips
I had a unit that I repaired as mentioned above and then it had a high pitch wine. I replaced the next cap up C52 another 47mF I believe and this took care of the wine.

On another unit I had, the headphone output was almost gone one one side, there are two 100Mf caps on the board near the headphone jacks, replacing the appropriate one took care of this problem.

Here is a troubleshooting tip for you all, if you don't want to replace all these caps at least buy them as they are only a dollar or less each. Take your zoom apart, hook up your guitar, plug in headphones or into amp, now jumper the appropriate capacitor accross each of the previously mentions suspect caps (make sure to apply the cap in the correct polarity because an electrolytic cap will burn up if connected backwards). Assuming you only have one bad cap your sound will come back when you have jumped a good cap accross the dead one. If there are more than one bad componants you will need to just change them all out.

As mentioned by someone else in a post, I too will be willing to do these repairs for you if you wish. I also have new batteries for these units. My email is tothemcatees@yahoo.com

: Okay, I just repaired my third one and this time it was the 7660 IC chip. I tried the caps first and that didn't do it so I bought a 7660 from Digikey.com for less than a dollar and put that in. Now this one is working too. I found that testing the voltage on the chip before repairing had the same symptom (no -5v between pin 3 and 8) regardless of a bad capacitor or bad IC7660.

: I only know for sure that the end 10mF cap is the charge cap but the next two 47mF caps may be part of this charge circuit as well. Any way you look at it, it costs less than $5 to change out the caps and IC. Hope this helps.

Re: Pin numbering of ICL 7660

With all due respect to Mark, since his posts are extremely helpful, there seems to be an error with regard to the pin numbers of the ICL7660. Mark says "no -5v between pin 3 and 8" but the pinout of the ICL7660 SOIC pack has pin 3 at ground, pin 8 at V+, and pin 5 as Vout. Thus you would expect to find -5V between pins 3 and 5. The voltage you would read between pins 3 and 8 would be the POSITIVE battery voltage. Hope this info helps someone out.

Re: Pin numbering of ICL 7660- correction noted

Good to see others posting and I believe your right, Gary. Here is the .PDF from Digikey.com on the IC7660 which cleary shows pin 5 as -5 volts with reference to pin 3(ground) as you mentioned and Pin 8 as + voltage supply.

http://www.national.com/ds/LM/LMC7660.pdf

I have used this chip as a replacement with success although most of the 9002's I have worked on only needed the capacitors accosiated to the IC7660 replaced.

I have made a webpage to collect Zoom 9002 information such as repairs and a new battery, visit it here: http://home.comcast.net/~mmph/guitar.html

: With all due respect to Mark, since his posts are extremely helpful, there seems to be an error with regard to the pin numbers of the ICL7660. Mark says "no -5v between pin 3 and 8" but the pinout of the ICL7660 SOIC pack has pin 3 at ground, pin 8 at V+, and pin 5 as Vout. Thus you would expect to find -5V between pins 3 and 5. The voltage you would read between pins 3 and 8 would be the POSITIVE battery voltage. Hope this info helps someone out.

Re: zoom 9002 troubles.can anyone help me?

Mine has a similar problem as those already posted. Mix input, metronome and tuner sound perfect, while the guitar input sounds "distorted", not mute. This weird distortion sounds like something broken, and it's not musical and it changes when i switch from low to high input gain.
Do you believe i can fix this trouble as those already posted?
thanks bye

Re: zoom 9002 troubles.can anyone help me?

Okay people, I've looked everywhere and only found incomplete references of repairing a zoom 9002 and some people claiming they did it but no details..... I just repaired two of them and will now tell you how! Open it up, there are two circuit boards- you will be working on the one mounted to the back half of the casing. You have probably heard about the IC7660 by now and this IS the problem AREA but not likely the problem. It is located on the long narrow end of the cicuit board next to the battery compartment at the very end on the bottom side of the board. This IC7660 is less than .25 inchs and is clearly marked on top of it; this chip it's self was not failed on either of my units so I left it in place. What I did change were the four capacitors on the other side of the board, starting from the end there is a 6V 10mF, two 6V 47mF, and a 16V 47mf capacitor. These are readily availible for less than $1 each, I didn't take the time to identify exactly which one had failed because that would have taken longer than just replacing all four. The capacitors are directional so pay attention and be sure to install the new ones with the the negative (black) side to the end of the narrow portion of the board as the originals are. If this does not do the trick for some reason, I would then replace the IC7660, these are also readily available for about $3, A good electronics website will even show a diagram that you can use to trouble shoot the chip by testing voltages on each leg but note the voltages will read out of tolerence when the caps are failed as well.

Both of my units had the classic no guitar sound but the metronome and tuner frequency still worked. Replacing these caps took about and hour and now both of them work perfectly. I hope this helps, I know how frustating it is to read all the dead end posts on the internet.

-Mark

Thanks Mark!

Just restored my 18 years old Zoom using your recommendations (replaced all capacitors). This is so fun to unzoom and hear again my oldie after 10 years of its silence. :-)

Kudos for your help!
ZOOM forever! :-)

voltage readings from working 9002 capacitors

Hi, I just fixed two 9002's so I checked the voltage after I fixed each and I decided to share the voltage numbers if you have volt meter. These readings will have some variance from each 9002, but the numbers should be within about 10%. The dark spot on the capacitor represents the negative side.

C56- (neg side) +2.5 v., (pos. side) -2. 3 v.
C55- (neg side) -4.7 v,(pos. side) zero
C54-same as C55
C53- (neg side) zero, (pos. side) +7.0 v
C52- (neg side) zero, (pos. side) +5.0 v.

Good Luck

Re: zoom 9002 CAPITORS uI/y3/x2x

Mark
Can you advise the name of the company that sells these capacitors. I have 3 units down with the fault you describe.
On inspection these seam to be leaking
Regards
John

Re: zoom 9002 troubles.can anyone help me?

: Okay people, I've looked everywhere and only found incomplete references of repairing a zoom 9002 and some people claiming they did it but no details..... I just repaired two of them and will now tell you how! Open it up, there are two circuit boards- you will be working on the one mounted to the back half of the casing. You have probably heard about the IC7660 by now and this IS the problem AREA but not likely the problem. It is located on the long narrow end of the cicuit board next to the battery compartment at the very end on the bottom side of the board. This IC7660 is less than .25 inchs and is clearly marked on top of it; this chip it's self was not failed on either of my units so I left it in place. What I did change were the four capacitors on the other side of the board, starting from the end there is a 6V 10mF, two 6V 47mF, and a 16V 47mf capacitor. These are readily availible for less than $1 each, I didn't take the time to identify exactly which one had failed because that would have taken longer than just replacing all four. The capacitors are directional so pay attention and be sure to install the new ones with the the negative (black) side to the end of the narrow portion of the board as the originals are. If this does not do the trick for some reason, I would then replace the IC7660, these are also readily available for about $3, A good electronics website will even show a diagram that you can use to trouble shoot the chip by testing voltages on each leg but note the voltages will read out of tolerence when the caps are failed as well.

: Both of my units had the classic no guitar sound but the metronome and tuner frequency still worked. Replacing these caps took about and hour and now both of them work perfectly. I hope this helps, I know how frustating it is to read all the dead end posts on the internet.

: -Mark

Hi Mark, Thanks for being a hero and posting this.I'm going to attempt this. Though I own a soldering iron, I've never changed a cap before. Don't know how. Do I lift the whole CB out and work from the other side? Perhaps you might be up for posting a repair video on You Tube? can you also suggest a supplier for those parts. I live in London. many thanks.
Rob

Cannot locate IC7660

Hi, I have a Zoom 9002 that is not working. I tried to follow your instructions, but I cannot locate the IC7660 chip. Nothing is marked as such. Are there any drawings showing where it is located? Thanks for your help.

Re: zoom 9002 troubles.can anyone help me?

everything is ok! thanks. the problem is IC7660 bad, caps is good.

Re: zoom 9002 troubles.can anyone help me?

Where can I get these capacitors? Can you suggest an online electronics store as I'm having difficulty finding these capacitor values in the UK.
Cheers,
Paul

Re: zoom 9002 troubles.can anyone help me?

Looking all over the web, where can i buy the capaicitors?

Re: zoom 9002 Parts, service, repair, and complete units avialable

In search of anything ZOOM 9002?

I am now fully supporting the ZOOM 9002 via my web store www.e-lectronics.net. I repair them, sell repair kits, new batteries, new batter door covers and buy broken ones.

For all your ZOOM 9002 needs, pay a visit to www.e-lectronics.net

See you there!

-Markcm

Re: zoom 9002 troubles.can anyone help me?

Ok , i m brazilian and i dont speack english very well , sorry. But i need you help me , my zoom 9002, dont turn on any light no display on nothing. I need to repair it. Can y help me .

Fabio Brasil.

Re: zoom 9002 troubles.can anyone help me?

It sounds like you might have a bad power supply. Your problem is not the common capacitor issue that most of these units have because those units will still power on. Do you have a voltage meter that you can use to test the power supply with? feel free to contact me with more questions at mmph@comcast.net and I will try to help you.

: Ok , i m brazilian and i dont speack english very well , sorry. But i need you help me , my zoom 9002, dont turn on any light no display on nothing. I need to repair it. Can y help me .

: Fabio Brasil.

Re: zoom 9002 - replaced caps - now won't power up

I purchased a 9002 on ebay and it arrived with the accursed charge pump failure. Seller offered to refund, but I love these little guys and I hate to see 'em die. Still working on it, but Mark - you are so right about the traces on the board - they lift by barely touching them. Fortunately, there are holes for soldering the new caps, but you've really got to take note of the positions and gently desolder the old ones out like a surgeon. Also, there is another electrolytic cap on the board above, such that when you are about to close the unit, it interferes with closure - you may need to check and re-check it before you finally drive those screws home.

ANOTHER 9002 RESURRECTED...

Thanks to Mark for his detailed guide on how to bring back to life the 9002,I´ve done it with mine(caps replacement only) and now is baddest than ever!;greetings from Barcelona-Spain- to all the retro-tech maniacs.

Re: zoom 9002 - replaced caps - sounds good

Well, it's up and running. Thanks to everyone, esp. Mark for posting this excellent repair. If these are the symptoms of your non-functional 9002, you could do worse than give $5 worth of parts a try. DO follow all instructions you see here, making note of anything that can further damage the unit, and DON'T try this unless you are very patient, good with a soldering iron, and have a decent knowledge of circuit board layout. You may need to move the large capacitor on the top board to make room for the new (and certainly better) capacitors.
Cheers, and good luck to all!

Re: zoom 9002 troubles.can anyone help me?

: Ok , i m brazilian and i dont speack english very well , sorry. But i need you help me , my zoom 9002, dont turn on any light no display on nothing. I need to repair it. Can y help me .

: Fabio Brasil.

Hi from Spain Fabio. Same problem than you and many other 9002 users. Woderful unit!!! We must repair it...
I´ve found this web page

http://home.comcast.net/~mmph/Zoom/Zoom_9002_repair.html

I think it contains the solution to our problems.
It´s all very well explained and the components needed are cheap and easy to find in any electronics store.

Some welding is necessary so you have to be careful with the circuit plate. Follow the instructions carefully or get some electronic-friend to help you.

Hope it helps

Good luck

Jorge

Re: zoom 9002 troubles.can anyone help me?

I too have this problem. Ive been in electronics for 15 years. I have the know how but would like a schematic. I have no sound using the input jack. I still get a tone with the tuner on and the metro still works so Im sure the audio path is good. Just cant hear the guitar or the effects either. HELP!!!!

Re: zoom 9002 troubles.can anyone help me?

Hey I bought one off ebay a while ago with the same problem > cant Help you with the schemataic but email me and I can send you a pic of where the capacitor that causes the problem is

hey it's C56

I just looked in the junk one I have and took the pic but its C56 Lower left side right next to the battery compartment. The bottom one. Let me know if you want that pic. I dont come here much so email me.

Re: zoom 9002 troubles.can anyone help me?

Oh ya......my "wall wart" went nuts and was putting out 11.5vdc instead of 7.5vdc just before this happened. I just assumed the Zooms power distribution section had protection for this seeing as most electronics devices have some way of "clamping" excess volstge to keep from damaging other stuff.

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