ACCURATE Mesa Boogie Road King (mk.I) schematics, anyone?

[asfi]

I've been wasting too much time attempting to fix the demon horror (from the technician's point of view) called the Dual Rectifier Road King (Mk.1 version). I was able to obtain a set of schematics from Mesa Boogie but they are riddled with inaccuracies and errors, despite confirming with a tech there that I really do have the "right" ones.

For instance, numerous unlabelled components, several of the 27 (!!!) relay coils have designations which match no set of contacts, relay coils with nothing driving them, nodes shown as grounded on the schematic but which clearly are not so on the circuit board, and so forth. This amp is seriously sapping my will to live....

So I'm wondering if anyone out there has been in a similar predicament, and has already traced through the circuit and has annotated the official drawings accordingly. It may save me from having to lug this beast into the parking lot and ceremonially setting fire to it.....

[J M Fahey]

Send it to them.
No joking.
Besides, I think they have some kind of "fixed price" offer.
Let your customer waste his time/money straight with them, do not get involved in this mess.

[Enzo]

Aren't some of those "relays" actually LDRs?

[asfi]

Aren't some of those "relays" actually LDRs?

There are a dozen 4N33's in addition to all the relays.

And now I've just wasted another hour sorting out why a whole gang of them were buzzing like crazy.....turns out I had two of those nasty non-polarized, un-keyed IDC cables transposed.

[T9c]

Agree. Rich told me it would be $200-400, depending on how many tubes it needed. I knew the entire pre board would have to be replaced, since there was a huge hole in it from it catching fire. Also, the ETA was 3-4 weeks. Considering the cost of this head, I thought it to be a pretty good deal.

Send it to them.
No joking.
Besides, I think they have some kind of "fixed price" offer.
Let your customer waste his time/money straight with them, do not get involved in this mess.

[asfi]

Fixed!!

Root cause of the amp's woe was the EL34 triode/pentode switch. It was arcing through, splattering noise into the output transformer's primary. Spark-gap generator = this is not the sound you're looking for.

Along with bad soldering in the B+ supply, and a weak short between the filament supply and GND....yikes.

Not so much a repair job as an exorcism, IMHO.