4 Input Jcm 800

[g9j]

Hi,
I am trying to restore my 4 input 50 watt 1987 jcm 800 with a 1990 stamp and 89 Drake transformers.
I cannot find the original circuit and i wonder why it has a JAPAN stamp on the chassis.
I want to change the pots which are the PCB type.
Please share your comments.
Thanks
Gerry

 

[SpHj]

The Japan stamp probably meant it was for export to Japan, as for the circuit it's probably either a '68 or a '72 spec lead model. Post a clear pic of the circuit board. There's plenty here that'll be able to tell right away what era circuit it's based off of.

 

[g9j]

Thank you for that quick reply... here are some pics... I could not attach them before due to their size...

 

[g9j]

The chassis label

 

[g9j]

Circuit pics!

 

[g9j]

The pots are not original... I request anyone to direct me to the links where I can buy the same.. I am aware that mojotones have them but I don't know which ones to buy... any help appreciated...even the right Circuit diagram...Wiring for the 4 inputs....cap set list...and the 1st vol control is acting like a treble tone control due to some wrong wiring.

 

[g9j]

The pots are not original... I request anyone to direct me to the links where I can buy the same.. I am aware that mojotones have them but I don't know which ones to order

 

[SpHj]

Pots appear original, Same ones in my '89 JTM45RI

Whats the uF rating on C1 and C2? can't see in the photos. It's a split cathode for sure.

 

[g9j]

Here you go!

 

[g9j]

S/A 50 watts
X 1989

 

[g9j]

It's using KT 90's at present

 

[danfrank]

The pots are not original... I request anyone to direct me to the links where I can buy the same.. I am aware that mojotones have them but I don't know which ones to order

3 X 1Meg log or audio taper
1 X 250K linear taper
2 X 25K linear taper

 

[g9j]

3 X 1Meg log or audio taper
1 X 250K linear taper
2 X 25K linear taper

Thank you. much appreciated!!!

 

[johan.b]

Someone had a little fun with the model sticker on the back. ..output power 800 watt. .ha. ..
j

 

[g9j]

Yes i saw that... they did not understand that 50 watts is enough to blow your ear drums