Hi,
Not a frequent poster here but hope someone can help.
I bought an old Harrison X150 amp a couple of months back from Ebay and after a few minor repairs (replaced volume pot and mains switch) it was
up and running, sounding remarkably good for a 27 year old amplifier. In case i ever needed to do a more complex repair, i trawled the internet looking for a circuit diagram and managed to find lots of references to HH Electronics VX-150 schematic which looked very similar to the X150 (i know about the history of Harrison, HH and Laney). In the meantime, another X150 came up on Ebay and i snapped it up with a view to having a spare or experimenting with bi-amping etc. The second X150 looked identical except the Plug-in modules on the back panel were recessed.
I did all the basic power-on tests before plugging it into my system. First thing i noticed, the output volume even at maximum level was very low. Removed the lid and was surprised to see totally different internal electronics from the first X150. Clearly, a later revision but without the two VCA plug-in modules which the first unit has. That probably explains the lack of volume? I dont suppose anyone out there has a circuit diagram that includes the VCA module or a couple of spare VCA modules lying around? i have posted pics to help identify. Ta
Not a frequent poster here but hope someone can help.
I bought an old Harrison X150 amp a couple of months back from Ebay and after a few minor repairs (replaced volume pot and mains switch) it was
up and running, sounding remarkably good for a 27 year old amplifier. In case i ever needed to do a more complex repair, i trawled the internet looking for a circuit diagram and managed to find lots of references to HH Electronics VX-150 schematic which looked very similar to the X150 (i know about the history of Harrison, HH and Laney). In the meantime, another X150 came up on Ebay and i snapped it up with a view to having a spare or experimenting with bi-amping etc. The second X150 looked identical except the Plug-in modules on the back panel were recessed.
I did all the basic power-on tests before plugging it into my system. First thing i noticed, the output volume even at maximum level was very low. Removed the lid and was surprised to see totally different internal electronics from the first X150. Clearly, a later revision but without the two VCA plug-in modules which the first unit has. That probably explains the lack of volume? I dont suppose anyone out there has a circuit diagram that includes the VCA module or a couple of spare VCA modules lying around? i have posted pics to help identify. Ta
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Hi Roclite
Did you get anywhere with this HIT amp? I have one too which has failed. It looks similar but not identical to your 3rd JPEG. In my case it looks as though the zener diodes on the thermal overload displays have popped. I expect this also means that something more serious has occurred, because I doubt that both zeners would burn out for no reason.
Did you ever find a source of schematics for these amps?
Did you get anywhere with this HIT amp? I have one too which has failed. It looks similar but not identical to your 3rd JPEG. In my case it looks as though the zener diodes on the thermal overload displays have popped. I expect this also means that something more serious has occurred, because I doubt that both zeners would burn out for no reason.
Did you ever find a source of schematics for these amps?
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