New HRM build

[ic-racer]

I started out just drawing up the traces of the HRM boards for fun. Then I went and made the boards and populated them. So, at this point I am well on my way to a complete build.

I thought I'd start a thread, not as much for all to see, but to really commit to seeing this project through to the finish.

[ic-racer]

This is the schematic I'll be using. I drew it up a year or so ago. It is likely similar to an HRM in the early 200 range.

http://ampgarage.com/forum/files/ods_102_hrm_158.pdf

[ic-racer]

I got most of a layout done, but I'm probably not going to complete it. I'm just going to go right on to building the amp from here.

http://ampgarage.com/forum/download/file.php?id=5552

[ic-racer]

I drew out the traces for all the printed circuit boards and previously posted them here: http://ampgarage.com/forum/viewtopic.php?t=6098

[ic-racer]

I spend a lot of time getting the boards to look right.

[ic-racer]

As of last week the boards are nearly completed.

I finally got some 'real' Formica brand so I may re-do the main board with that. The main board in the picture was done with 4 sample sheets of Formica-clone material that needed to be laminated together with epoxy to get the correct size.

[ic-racer]

The schematic, and layout and boards were all based on pictures that were previously posted. The serial number of the amp posted was not given but it was in the low 200 range.

Here are a few shots. I don't recall where all the pictures are now but a link to them was posted a while back. I believe a fellow TAG member took the pictures.

[ic-racer]

Now I am finally at the point of needing a chassis.

The 80s ODS chassis from Thailand does not have provisions for the output OHM selector, and is best suited to an amp with a 4 ohm Fender Twin OT.
Since I'm a stickler for details, and this amp will have a Marshall style OT with an impedance selector, I don't want to use that chassis.

Admittedly I could not find a suitable chassis over a year ago and kind of gave up on this project.

Maybe someone has a Funk chassis or other that they are not going to use.??

[Structo]

Cool!

Looking forward to the build.

Hope you can find a chassis.

[ChrisM]

Question about the voltage doubler board, where does the post regulator filter cap go?

Also do you have the parts layout for the FET board?

[ChrisM]

That schem you posted looks a bit different than the final schem in your 102 thread.

The master's bright cap is different
The PI plates are reversed compared to to the last schem

[Structo]

Yes the plate values need to be reversed.

Also, don't most ODS have a bypassed 220K between the send and return jacks?

What value is the cap on the standby switch typically? .01uf?

[ChrisM]

Yes the plate values need to be reversed.

Also, don't most ODS have a bypassed 220K between the send and return jacks?

What value is the cap on the standby switch typically? .01uf?

That little filter on the send return jacks was more unique to #124 and was one of the neat features that made that amp so unique and nice. I think Funk said that he has seen a few other real ODS' with that passive RC network on the effects loop jacks before though.

That cap on the standby switch isn't critical in value. It's more voltage rating one if concerned about. I believe the cap is just there to reduce transient spikes.

[ic-racer]

That schem you posted looks a bit different than the final schem in your 102 thread.

The master's bright cap is different
The PI plates are reversed compared to to the last schem

Oops! Good pickup, version 1.0 vs version 1.8!
I'll update the one posted in this thread.

http://ampgarage.com/forum/files/ods_102_hrm_158.pdf

[ic-racer]

I'll tell you how I am going to do it without the complete layout. The same way I did my #124.

Because the schematic was based on the pictures, to avoid errors, I pretty much built it by looking at the pictures. I had a computer monitor on the workbench with the pictures as I worked. (in addition to the schematic).

I'm planning on wiring this one the same way.

Speaking of wiring. It has been quite a few months since I addressed wire type. I had a pretty good understanding of what was needed for #124, but I wonder if someone could give a recommendation on the wire likely used on this era amp. Size? Core? Casing?