Repairing the Roland CR8000 Drum Machine
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- čas přidán 24. 08. 2024
- This video is another in our series on the vintage Roland CR-8000 analog drum machine. In this episode we will be repairing a machine that suffers from a few of the failings that are common to this instrument and other Roland machines of similar vintage. In our video introducing the CR-8000, we mentioned that the momentary switches are a common source of failure, and we will be digging into these and other problems in some detail here.
What an incredible restoration! You always go above and beyond with so much detail. And you are a wonderful teacher too. Always learn a lot and look forward to your videos! I’ll bet a lot of hours went into this!
Thanks for your encouraging feedback and support Neal, it means a lot! I'm glad you enjoy the content. Cheers!
You, sir, have my utmost respect. Not only capable and dedicated but sharing it with all of us.
Wow! Thanks for the encouraging feedback! I'm still learning as I go and enjoying the process, props from viewers like you make it worth while.
Yes! Been waiting for this one since your last video.
Great info on the glued tact switches and what you pointed out during disassembly. I had some problems with disassembly too, which sadly lead my repair to a halt as I didn't want to make some more damage.
I've indeed lost one spring trying to open one of these switches, because it would not let me pry the tabs as I thought. I didn't see/understood that there was some glue between the top and bottom plastic pieces between those tabs.
As I've said, I actually stopped my repair (I'm talking years ago now) because of this and never continued because I've seen the fragility of these switches and was afraid of possibly breaking some tabs or losing more springs. So thanks for this info/warning.
I have since bought a replacement switch which is supposed to go on boss pedals. Looks similar but the schaft is different i.e. much longer. But it looked similar enough that I thought I would try to combine new and old, reuse the old switch and put the spring of the new one in it, hoping that they are a match.
I also have an idea with opening the switches, and that is to use a fine cutter blade prior to pry open the switches in order to unbound/cut the glue beforehand.
Thanks again for all the information you put up, and I am waiting eagerly for your next CR-8000 installment. MIDI mods and eventually tone mods are for me utmost interesting!
Thanks for your comment and thanks for watching. To be clear, I don't believe there should be any glue on these ALPS switches as they left the factory, all the glue on the switches/PCB/faceplates/case of this CR-8000 seems to be the result of some kind of messy attempt by a previous owner to glue down bent faceplates/labels. It almost looks like they were attempting to apply some glue and then the top of the bottle fell off, I can't imagine otherwise how they would make such a mess. Most of the switches seemed to have little to no glue holding the switch together, but it might be that I was unable to tell the difference between what was there originally and what came later. Were yours glued?
@@telefunkian well it's been a long time, so I don't know for sure. But it surely didn't occured to me that they could be glued. Nevertheless, I did find them hard to open, and that's how I've lost one spring when opening my first switch. It simply flew away, and for the life of me I could not find it on my floor, having spent an hour looking everywhere...
As for the faceplates, they were holding with double-sided tape and I think it's the way it is supposed to come from the factory. I did remove them using hot air (on low temp of course) which worked well. My CR didn't have glue on the PCB nor on the switches tho, so there's that.
Incredible work! I'm a complete amateur at electronics troubleshooting, but I learned some things from your video. I am currently restoring an Ensoniq EPS and I've traced the problem I have to the motherboard. Being 34 years old, even though I can't be certain the problem lies in the capacitors, would you recommend replacing them all anyway as a starting point due to age? Thanks for the great content!
Toolman, thanks for watching and your feedback! With respect to your Ensoniq and the question about caps, I have not worked on an EPS but I have found some equipment from the same era (late 80s to early 90s) to be filled with bad caps (high ESR and high electrical leakage), even worse than early 80s, and that replacing all the electrolytics was able to 'rescue' them. That being said, the approach I might take FIRST would be one that you may have already covered, checking all the voltage supplies from the power supply etc with the motherboard and other headers disconnected. The EPS is documented in the service annual as having PSU issues manifest as apparent motherboard issues. SECOND, I would make sure none of the power rails on the motherboard are shorted by disconnecting from the PSU and checking resistance between the power rails and ground and each other. If you find a short you have to fix it first. Once you are satisfied that you are not shorting the power rails and you have true +5, -5 and +12 and -12 on the CPU board where you should have it, try to find life in the MPU, can you see a clock pulse or other signs of life if you probe with an oscilloscope? There are not very many electrolytics on the main board, so replacing them would be cheap, but don't hold your breath as it might not fix your problem... good news is that I believe most of the chips etc can be found and even some EPS motherboards pop up on eBay from time to time for cheap. Cudos for you for trying to fix this yourself, but at the end of a day it might be a job for a pro tech, it just depends on your appetite for adventure and learning!
Just curious if you plan on uploading the video showing the steps you took to calibrate it? My hand clap sounds pretty weak and I really liked yours in the sound clips you used in this video. I've made some adjustments per the service manual to the noise level and handclap offset, but still can't quite get it to my liking.
Thanks for the reminder! I've gotten distracted by a couple of other projects (fixing an RME ADC/DAC and an Apogee Symphony) and my 'day job' has been pretty busy lately. Hoping to get some videos posted in the next few weeks but it will be a while before I get the CR8000 calibration one up, sorry!
Wow. Great content. Looks great! Nice job.
Got a vintage mashine for repair but having a time finding (discontinued?) Nichicon 0.47uf & 2.2uf 16v caps..not available on Digikey or Mouser 😞 what do you suggest?
Thanks in advance.
Thanks for the encouraging feedback. If you are having a hard time finding electrolytic caps as many series are being phased out over time, try to find a suitable replacement from the same manufacturer (similar purpose audio vs. power) then others (Rubycon, Panasonic, ELNA). Don't worry about going up in voltage, within reason, but stick to original capacitance. When selecting replacements look at the intended use of the original, where it is in the circuit etc. In a pinch you can use polyester film caps for some audio circuits but you will get more high frequency content coming through. XRayTonyB has a recent video on caps in audio, czcams.com/video/fzrP-EeMb1Y/video.html
There are several other videos on the subject. Your experience is not unique, as stock in some common items like caps is low globally.
Nice job!
I hate these rubber dome switches with conductive pads. They look like standard computer keyboard switches. Wouldn't it be possible to replace them with mechanical keyboard switches?
Sometimes some retro/vintage resto/cleaning/repair is a labour of love, especially when you have to mostly clear a board of components to deep clean it (going through that now with a Commodore 1701 monitor).
Just curious who you had print off the label? I no longer have Ai, but I have gotten good with Inkscape. Would be awesome to be able to print off such labels!
I used a company here in Vancouver called TPH, The Printing House, but they are franchised and you should be able to get it done anywhere where they can cut with precision. In the end the color was not perfect but I gave up caring too much! I almost caved in and bought a computer controlled cutter myself (CRICUT?) to try DIY.
I just bought on of these on reverb was told it worked perfect but some buttons don't work and it's just stuck looping the intro/fill beat over and over it won't change loops none of the presets will work or programed beats:( any idea on why it would just be looping the intro fill over and over instead of jumping to the actual beats?
@keyboardkingpin, Wow, I am sorry to hear this as it sounds like you may have been ripped off by the vendor on Reverb. I am going to give you a quick guess as to what might be happening, but without having the machine on my bench I would have to emphasize this is a guess... Three major possibilities come to mind that could explain the fill issue, but that is only part of the problem; 1. There is a problem with IC1 or IC2 on the "Control Board" (page 9 of the service manual). These are 4503 non-inverting hex buffers. If you can check pin 6 on the control board (page 8 G2) , it should be held high by R12. If it is low, then something could be wrong with IC2. Pin 41 on the Control Board should also be high, (page 8 F12). If it is low there may be something wrong with IC1. Compare the voltages of pins 2 and 3 on IC2, they should be the same, and pins 6 and 7 of IC 1, ditto. If all that checks out OK, then maybe #2 or #3. Possibility #2: The connections between the CPU board and the Control Board are broken/not working. Examine wires going from 39-46 on Control Board to 40-47 on the CPU board (connector P6) If you have a soldering iron perhaps reflow these. #3: Your CPU could be fried.... The CR8000 does not store patterns in an external EPROM, rather they are burned in mask ROM. If the CPU is stuck playing fills even when it is getting no 'fill' signal from the Control Board, something is probably wrong with the CPU. Your other issue is bad switches, as described in the video you are commenting on. If you have a multimeter you can check the resistance values across the switches when you press on them, it should come close to 100 ohms. It is a big job to take them apart and clean them, but it can be done, assuming they have not been ruined by the previous owner. Where are you located?
And if you don't mind me asking what was the vendor charging for a 'perfectly working' CR-8000?
@Telefunkian 800 he was asking 1000 I should of known there was a reason he was discounting it. Also the the zero feedback had me nervous. Should of went with my gut instinct!
@@keyboardkingpin Again, terrible to hear you were ripped off. I know how frustrating that can be, it is truly maddening! I don't know if you are near any good pro techs, but it might be a job for them, but I suspect not cheap. I'm not a pro tech, just an enthusiast who enjoys showing folks what these things are made of and what makes them tick. If you were local I could look at it but I am in Vancouver Canada.
@Telefunkian It is a real bummer and actually I bought this from salt spring island british columbia lol. He refused a return request but the item was not as described,So I'm hitting up reverb? And if that doesn't work i'm going to call my credit card company. If I'm stuck with it guess I need to learn how to fix it myself. I bought a CR-5000 a while back on ebay with issues but seller gave me a nice partial refund. I thought I'll take it up to a local vintage synthesizer repair guy up in portland. The guy sat on the unit for a year and a half Until I showed up there and demanded the unit. He said there's too many issues with the unit however he would like to trade me a working RZ-1. I took the trade and the casio Rz-1 had issues I discovered later. I'm not sure what I'm gonna do with this unit. If I can't return it basically just took a fat L. And sell it for less then I bought it.