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ChromaTalk Archives: July 2003

Re: MIDI 9 Retrofit

Rich Hilleman [21030351+]

Go to first message in thread (June 2003)

Looks like I will get this on the 8th. I will take in my Rhodes the day it comes in (It has a broken Tine anyway) I should have a review from either Peter Miller at CAE or me about a week later.

Chroma Battery Replacement?

Paul Tillotson [21030218]

I have been a happy Chroma owner for a year now, but suddenly the honeymoon is over. There were several instances lately where my beloved would shut herself down while I wasn't looking, within the first hour or so after warm up. Then, yesterday she dumped all her patches on bootup. Okay, I reload the patches- factory set # 2 a huge improvement over factory set #3, also known as the whitebread bank, which I've been suffering with for a good while because I'm too lazy to load another set. I'm happy for the evening because I'm playing with more interesting sounds but once again she shuts herself down. I finish the project I'm working on, ignoring the Chroma for the rest of the night. Today she again powers up with no sounds and no audio at all. But now I can't load new sounds because it refuses to stay in the load mode, it immediately returns to the preset mode and ignores the cassette dump. I'm stuck. I was hoping that changing the batteries would resolve these troubles, but the Chroma is mounted at about face level with an Xpander on top. Before I start dismantling my studio and injuring myself and the studio- is my recollection correct that the Chroma uses AA batteries that are replacable by me, an idiot?

I know that my Chroma does need some qualified attention- I've grown confortable with error #3s and the uneven response from a few keys that only register full velocity, but now we've entered a new era of fear and desperation. Any recommended repair places in Seattle/Portland/Vancouver? I do have a couple pieces at Backline in Vancouver so will doubtless be visiting there again.

Thanks, PT

Mark A. Lange [21030459+]

You're right - the Chroma's batteries are AA, and all you have to do is remove the 4 screws on the switch fascia. The front lid will lift right up, and the batteries will be on the right hand side.

As far as a repair center goes, I waited for years before I finally picked up mine from a Seattle shop and have begun repairing it myself!

Murray Macdonald [21030276+]

TIP: Keep your chroma's power ON while replacing your batteries and you will not lose your patches. Always have a backup just in case.

When Z4 smokes it's very bad!

Mark A. Lange [21030459+]

Hello Wise Ones!

After years of waiting on others, I took it upon myself to repair my Chroma (SN: 21030814). I've got all the docs and the basic diagnostic tools, but not a whole bunch of experience in the component level domain. I did achieve what no one else had done - I got it working - and it was sounding wonderful!!!

Emphasis on the word "was."

An old, wizened tech once told me, 'There's a little bit of smoke in everything, and when it comes out it's very bad.' After three days of cycling power up and down and playing without a glitch (all voicecards working!), Z4 on the power supply (the Overvoltage Protector) smoked Monday morning!

Actually on this Chroma Z4 is an axial diode labeled NTE4906 - (probably 5W) - while on my poor old broken machine (SN: 21030459), Z4 looks like the Overvoltage Protector Board in the component layout diagram with a TT-case/mounted diode labeled L60V6 (made by Lambda, I think, and out of production).

Just for grins I swapped it (the Z4 board) into my smoked power supply, but no dice - the front panel simply 'freaks-out.'

Anyone with any insights for troubleshooting/repair would be greatly appreciated. I'm unsure if the NTE4906 is actually a factory installed item, or a component replaced by a repair tech in the past. If it isn't, how about pairing up (in series or parallel?) 2 NTE4906's to increase the power handing capacity? Should I bag it all and install another supply? [Don Tillman was kind enough to await info on some current PC ATX supplies as possible replacement candidates, but was leery of the fans - as EFI/RFI is not a friend to the Chroma].

Thanks so much in advance - regionally (Seattle) there are absolutely zero techs to take this to - I actually waited over three years for the last known "Jedi Master Technician" and unfortunately he passed away prior to finishing the gig. Hopefully my questions and reasonings don't seem idiotic, as a little knowledge can be a dangerous thing - corrections are welcomed :)

I have heard the Chroma, and must hear it again.........

Murray Macdonald [21030276+]

NTE are commonly replacement parts. I suspect it was changed in the past.

As for the front panel "freaking out", does it just come on with random lights, or do you see activity?

Mark A. Lange [21030459+]

Thanks Murray - the front panel lights up almost all LEDs, solid (no activity), until it is powered down.

Murray Macdonald [21030276+]

What you describe is typical when the microprocessors are not running. First I would verify all of your supply voltages, then look for signs of the CPU clocks oscillating. To do this you would need a scope or a good logic probe. If the processors are running, (there are two, the main one 6809 and the keyscan 8039) then you can continue to debug from that point. I bet they are not both running as pretty soon after booting, the LEDs are normally cleared. If they are not running you should check the reset circuit.

Malte Rogacki [21010091]

I second that. I've also experienced similar problems when the reset voltage wouldn't reach the full 5 volts (or whatever amount it was). I also recommend exchanging all the (smaller) electrolyt capacitors in the power supply. At least in my case that did the job.

Murray Macdonald [21030276+]

An old tube amp tech I once knew said:

"If old caps aren't a problem today, they will be tomorrow. If something you like is already open on the bench, just replace them."

These are words I try and live by. New caps are a good thing.

Mark A. Lange [21030459+]

Thanks! Armed with scopes and caps I'll jump into it tonight.

David Clarke [21030085++]

L60V6 Reference

Does anyone actually have a data sheet reference for this specific part? (It would be nice to have one, and I've never stumbled across one).

David Clarke [21030085++]

Thanks! Armed with scopes and caps I'll jump into it tonight.

Mark - any good news to share?

Mark A. Lange [21030459+]

Thanks for asking, David!

A family emergency has kept me away over the past few days, and no additional troubleshooting's been performed.

However, the NTE4906s (substitute parts - less than $2 ea - I ordered 6) will arrive on Monday or Tuesday.

I do have info on the substituted part (NTE4906) at the following link:

After much searching, L60V6's were only referenced at and just for grins I put in a request for bid. Their minimum order is $500!!!!

Call me crazy, but I think I'll replace the entire supply, first :)

Thanks again for all of the help.