Solid State Guitar Amp Forum | DIY Guitar Amplifiers

did not power on
found an open fuse
replaced fuse
put on dbt looked good
powered on but has no trace

crt is glowing a little but not much

IMG_20230414_093836320.jpg

the slide switches are extremely stubborn

IMG_20230414_093822063.jpg

you practically need a hammer and chisel to move them

 :)

I am aware there are crazy high voltages in these things so I havent fooled with it  :) 

With the Sweep in NORMAL mode, there won't be a sweep unless you get a trigger somehow.

With EXT trigger source, you won't get a sweep unless you connect a signal to the External Trigger Input and adjust the trigger level control to get a trigger.

A drop or two of contact cleaner in each of those switches will free them up. Don't touch the end of the CRT tube shown in the picture.

hello everybody i think i want to try to get a trace on this device by (with your assistance) checking the power supply

obviously i (we) want to steer clear of high voltage areas

the same pics of the schematic are all over the net

IO4540_04_LowerLeft.jpg

IO4540_03_LowerRight.jpg

IO4540_02_UpperRight.jpg

IO4540_01_UpperLeft.jpg

thanks for your help meanwhile i am going to look for some (low) voltages to check

Do you have any wall warts with AC output ?
A nice small 9v AC would be a good test to do.
The older heavy DC ones usually have a transformer in them, you could test the DC voltage on AC and look for a ripple.

thank you sir that is an excellent suggestion

today I decided to look at this thing...todays goal was to be able to find something on the device then locate it on the schematic...or vice versa.

I was able to locate the two (bridge rectifiers)? and then test the voltage at point T (white wire) and I got 193v. (supposed to be 185v so I guess that is good)

one thing i noticed was the two rectangular resistors next to the diodes were pretty warm maybe that is normal but ones elsewhere were room temp.



IMG_20230815_152407994.jpg

there is a voltage between d408 and d410 supposed to be 19v but i cant find a place to put my probe to test.

Those wirewound resistors are 5 watt and 10 watt for a reason, so they will get hot.