Roland Re-201 Voltage Problem! Edited for Help!

[inputhone]

hey folks. i have a re-201 here, which really is not running good and seems to have some wrong voltages compared to the shematics. first i measured like hell and now, after a few fixing attemps, i tracked it down to be already wrong when measuring on the rectifier after the transformer.

see here: http://www.omegav.ntnu.no/~karlto/space_echo/page12.png

after d13 and d16 i do not get any halfwaves on my scope just crazy messy pictures. i thought the only thing that it could be is the diodes itself, so i swapped them and the elko which is loaded afterwards. but it did not change anything. for the other wirings (red and grey) i can see the right rounded saw-function with 10ms for one period, which i assume is right.

on the wirings at the transormer i do messeaure:

grey wiring: 10VAC
yellow wiring: 14VAC
red wiring: 22,7VAC

here is the service manual: http://www.omegav.ntnu.no/~karlto/space_echo/serviceman.zip

the weird thing is, that also on the pin40 and pin39 i do get less voltages (approx. 2-3V less) than said in the shematics. even though the diodes and elkos are fine. also where it says 13V in the shematics (at d12) i only get approx. 10V which is really weird.

on the pin44 it's the same mess as after the diodes. here is a picture:

i ran out of ideas. this sucks, what could it be?
thanks a lot for helping.

 

[inputhone]

anyone?

 

[zebra50]

after d13 and d16 i do not get any halfwaves on my scope just crazy messy pictures.

I don't know this circuit well, but as D13 feeds a cap and a motor, you should not expect a good looking half-wave on the scope. The cap is filtering the supply, and then motor and subsequent circuit is drawing who-knows-what.

 

[inputhone]

Hm, but the Motor-Circuit is after the Rectifier. I mean the cap gets load by peak AC from the trafo and should give out some DC that on can measure. If i have 10VAC i think it should be multiplied by 1,4 minus the voltage of the diodes which would make something like the 15V. But i cant measure any DC current after the cap. Also not on pin44. Even my multimeter just goes up and down in the mV area. But it should say 11V on pin44.  ???

 

[inputhone]

I mean, could it also be from the Motor-Circuit? What if i try to cut the Circuit for once, does that might help to find out if it's due to that? Or will that change the voltages even more?

 

[PRR]

> here is a picture

Not much help without knowing the 'scope settings (AC or DC, volts per division), and if the 'scope is connected correctly. Unlike the other power supplies, the motor supply may not be connected to circuit common. If not, then the 'scope will read the meaningless hash coupled through transformer capacitance, not the voltage that the motor feels.

Put DC voltmeter directly across C113. Does it say 12V to 15V?

Is C113 at least 1,000uFd?

 

[inputhone]

i always measured to ground. i put it across the c113 now i can read 16V.  :

but still why do i have so different voltages already on the pinouts of the supply circuit? i only recognized this as some voltages inside the unit get even more wrong. the pinout for the reverb just does not get loaded enough. it says approx 1Vpp instead of 7Vpp.

I also realized that the core inside L21 (connected to pin14: http://www.omegav.ntnu.no/~karlto/space_echo/page6.png) is broken and the bias leakage on R48 is higher than it should be in the service manual. Might that be able to affect the whole circuit that much?

thanks for helping out!

 

[PRR]

> really is not running good

What is it doing? Or not-doing?

 

[inputhone]

The unit has been tried to be fixed by somebody else. first of all i needed to reconnect everything and replace q1 and q2 by some right values.

now its running good, but you can't just approx calibrate it to the service manual, which means output just gets almost as loud as it should, a little less. and the main thing is that the reverb won't work right. it's super quiet almost nothing. when i measure between the pinout that goes to the reverb to ground i only get 1Vpp instead of 7Vpp. i replaced most elkos around there but did not help.

thought about beeing the ic but those never break as i know, and the voltage is already less than .8Vpp bevor it arrives in the citcuit (where the jumper is).

any thoughts?

 

[inputhone]

any thoughts?