Crumar Musical Instruments User Group.

----- Original Message -----

From: chocolatepistons

To: crumar@yahoogroups.com

Sent: Saturday, July 23, 2011 7:51 AM

Subject: [crumar] Roadrunner 2 - help with repair / schematics

Hi guys,

I just found this old Crumar in the back corner of a charity warehouse amongst a pile of electrical chaos marked 'to be tested or binned'. They couldn't test it, but the look of it made me nostalgic so I gave them a tenner for it anyhow.

Now I don't have much experience with old synth's etc, but work in car diagnostics and tuning so have a degree of electrical knowledge, maybe not heaps on the circuit level though.

It doesn't look too complicated inside and I can gauge an idea of what each board is doing from the wiring but I cant get any sound out of the thing. I've got it powered up and am getting a couple of DC outputs from the transformer circuit thing (around 15v which feeds most of the boards, and 30v which feeds the main bar where the keyboard acts on).
I'm not really sure where to go from here though, any pointers? or does anyone know where I can get a service manual or schematics that might help me? bearing in mind I'm on a pretty non existent budget.

Thanks in advance for any feedback,

Phin

>
> Hi Phin I have never worked on a Roadrunner I only experience is with a Crumar accordion tone generator. You should try to get a schematics and you will need a good scope It probably uses chips for output and you need to know the proper pins so you can look and trace the waveforms, good luck.  Mike  
>   ----- Original Message ----- 
>   From: chocolatepistons 
>   To: crumar@yahoogroups.com 
>   Sent: Saturday, July 23, 2011 7:51 AM
>   Subject: [crumar] Roadrunner 2 - help with repair / schematics
> 
> 
>     
>   Hi guys,
> 
>   I just found this old Crumar in the back corner of a charity warehouse amongst a pile of electrical chaos marked 'to be tested or binned'. They couldn't test it, but the look of it made me nostalgic so I gave them a tenner for it anyhow.
> 
>   Now I don't have much experience with old synth's etc, but work in car diagnostics and tuning so have a degree of electrical knowledge, maybe not heaps on the circuit level though.
> 
>   It doesn't look too complicated inside and I can gauge an idea of what each board is doing from the wiring but I cant get any sound out of the thing. I've got it powered up and am getting a couple of DC outputs from the transformer circuit thing (around 15v which feeds most of the boards, and 30v which feeds the main bar where the keyboard acts on).
>   I'm not really sure where to go from here though, any pointers? or does anyone know where I can get a service manual or schematics that might help me? bearing in mind I'm on a pretty non existent budget.
> 
>   Thanks in advance for any feedback,
> 
>   Phin
>

----- Original Message -----

From: chocolatepistons

To: crumar@yahoogroups.com

Sent: Tuesday, August 02, 2011 6:07 PM

Subject: [crumar] Re: Roadrunner 2 - help with repair / schematics

Ok.. wee update, I found my first faulty component, an op amp "UA741TC".
There are 6 of these on the P536 board (which I'm therefore assuming is the VCA?). I scoped the signals going in/out of them and one was dud (I swapped them about to double check).
This op amp seems obsolete now, but I can get a UA741CN which seems to have similar spec, although I cant find out if it is a direct replacement - If anyone knows for sure I'd appreciate a confirmation.
Hopefully there is no harm in giving it a go anyhow... fingers crossed.