Fender Fm212dsp effect card

[Strat]

Hi everyone....

I am Eugene from Kuala Lumpur, Malaysia...newly signed up....

I have a Fender Fm212dsp guitar amp for repair right now...the problem is that once the power is turned on,the amp just stays in the red channel irrespective of whether I push in the channel select button or not..

I have verified that it is the Dsp effect card that is the cause of the problem.....

therefore, would like to request for help from other members about this...better yet, does anyone of you have a spare Dsp card such for this model??


Thank you all for your help....

[Enzo]

Hi

Wow, I don't even have the drawings for that version. Have you contacted Fender for the schematics? Perhaps repair the DSP card?

[Strat]

Hi Enzo...will contact fender via email ...thanks for your suggestion...

the reason i am unable to repair the dsp card currently is because of the unavailability of certain parts in malaysia.....for example those hard to find ram chips etc....

i was having the idea that some of you guys operating fender authorised service centers might have some broken down amps lying somewhere waiting to be salvaged for parts....lol....

nice to know you, enzo....

[oc disorder]

Hi Strat

Some posts on this forum have had success just reseating the DSP chip.

I could be wrong as I don't have the schematic but ,I thought that just fets
were involved with the channel switching?

[Strat]

hi oc disorder...thank you for that information about reseating the dsp chip....will try that out shortly...

yes, the amp uses fets for the switching....I traced the path from the switch to the components around the switch including the fets..and ultimately links to the dsp card..the fets read normally...

furthermore, without a schematic right now, i am guessing that the amp works this way....

guitar input----> dsp board (for all amp modelling and effects) ------> preamp---> power amp
^
!
!
channel switch (should be controlling programs on the dsp chip)

once i removed the dsp board, there is totally no sound....it is not in a parallel loop witn the preamp or something unlike a spring reverb tank for example....

Will keep you guys updated....

[Strat]

Problem solved.....found out a IC with the part number cd4051 was the culprit..replaced it and works fine now...

Thanks all for your help and advice...

[Jazz P Bass]

So what was the CD5051 used as?
An AD/ DA converter?

[Enzo]

A CD4051 is an analog switch IC.

Part of the fine 4051/4052/4053 family of analog switches - or "selectors" if you prefer


Kinda like a 4066 or 4016 with some extra routing inpuits.