Crumar Bit One Power Concern

Hi, just bought a Crumar Bit One, I opened it up and cleaned it out and notice the power socket says 250 volts. I’m wondering if my Crumar requires 250 volts, I plugged it in to 110 and the lights were very dim, hardly any sounds and only after uploading the sounds via wav file into the tape in on the back of the synth did it produce some barely audible low low sounds (almost couldn’t hear). I’m wondering if I should buy a transformer to step up to 240V and see if that fixes the issue. The lights don’t stay on after I hit the tape button as if it’s drawn all the power it can and can’t power the lights. Basically can’t do anything with the synth in this condition.

I fixed the power issue by cleaning it out thoroughly, however I can’t seem to load it’s factory sounds. The results are a very low bass frequency and no other sounds. I was able to load the factory sounds at one time but the next day it was back to nothing again and won’t load the sounds. Any ideas?

I have a Crumar Bit01 and about the power supply issue reported on your first post, let me inform you that 250v is the maximum voltage admited for the power supply for 220/240 european models. For the 110v version the power supply is different and that’s why the symptoms you reported of the behavior of the synth. You MUST use a step up converter otherwise you can damaged other synth parts. 110 is lower voltage but has more amperage that 220. And you solved this with just cleaning ? Hummm.
About the tape load. Those synths were made to load from tape cassete and sometimes wav files have differently playing frequency not reconized by the synth. You must tried to put all the bass and treble controlar of the wav player, try up and down volume,etc. until you get luck. Takes time.
And did you replace the cr2032 backup battery? If not the factory sounds won’t stay in memory after power down.
Hope this help.
Best regards,

Hi MReis,

     Thank you first of all, it's so hard to find this information.  

Yes I did change the cr2023 backup battery. I was wondering about the step up converter, so even though my Bit One says 110v on the back I can still plug 220 into it? That was what I was confused about. It should be noted that my power board does not have the fuses that are in the photos of the Euro models (mine just has the main fuse on the back of the unit), I think I should install those fuses if I’m to use 220 converter perhaps. ?

The tape load information you supplied was very useful and I will try to mess with the eq frequencies and volume etc. Thank you.

Also one more thing, on the back side of the main mother board (P1082) I have some strange little jumper cables that I can’t tell if were installed from the factory or someone did so after the fact. They are located under the Static RAM chip number 19 (nearish to the back up battery). I wonder if this is the same with all models or just mine has been altered perhaps?

Thank you again for your information, again it has been very helpful!


Oh, by fixed it by cleaning; I meant that after cleaning, the lights now are much brighter and the unit stays on now even when I load into tape, whereas before the lights were very dim and the unit would shut off when pushing tape and load button. This seemed to be fixed after a deep cleaning of the unit.

Hi Michael,
Glad to know my info was useful.
As far as I know there’s two crumar bit01 versions. The earlier with the ssm chips for filter and the later with cem chips (mine is the earlier) and two power supplies, one european 220 and a us version for 110v. If you model says 110v (you can check thia info on the badge with serial number and inside on the ac plug) and you have 220/240 you MUST use a step up converter and vice versa (in that case a step down converter). I think you don’t need to put extra fuses because the crumar will run ‘thinking’ that is powered from 110v.
But if you tried to do it without a converter yet maybe you have damaged some parts and this is very risky and short circuit. You can also download the service manual for free on the web and the site has some information with pictures. You can compare to yours. It’s in german but you can translate it. You can also check if all voltages are ok if you have a digital multimeter. The bit01 runs at 12 and 5 volts, positive and negative. To do this test, I suggest to unplug all the connectors from the power supply to the other boards. But don’t forget to plug them again ONLY after the power is off.
I am on holydays rightnow and it’s been a long time that I have service mine bit01, and I don’t remember if mine has jumper cables, sorry. Maybe later I can tell you that info.
Hope this helped.

Best regards,
Miguel Reis

I should check the voltages again coming from my power supply. Although I believe the power problem has been solved, I will check again. After much research I believe I may have a faulty 8051 micro controller chip. I have bought a new one and a programming board, but I don’t know what file to program to the chip. Or even how to test this old chip properly. I checked DC voltages coming from all the pins and some gave no readings. I hope that makes sense. And hope you had a great Holiday!

-Michael Vermillion