mid 1980s riverhead guitar with active pick ups.

[darryl]

Just testing out this site.  

I have riverhead guitar I believe it's a jupiter model. It has active pickups, however the preamp has been cut out  ( I still have it)  but I have 0 wiring diagrams for this guitar.  Is there anyone here that can help me out? I can take some photos tonight and upload them.  There is not much info about these guitars.  This link shows the guitar I am writing about. 

dwyers.id.au/ant/guitars/gone/riverhead_jupiter.htm

[newey]

darryl-

Hello and Welcome to G-Nutz2!

Yes, at the least we'll need some photos of the wiring and of the preamp. I personally have never seen one of these before, so no actual insight from me on this. Is the guitar operable now without the preamp? Have you seen/played it when the preamp was working? (I'm thinking someone may have had a good reason to take the preamp out, if you weren't the one who did that.)

And, is the goal to restore it to its original active wiring with the original preamp or just to get it working again with an active preamp?

[darryl]

Aug 12, 2024 4:30:21 GMT -5 newey said:

darryl-

Hello and Welcome to G-Nutz2!

Yes, at the least we'll need some photos of the wiring and of the preamp. I personally have never seen one of these before, so no actual insight from me on this. Is the guitar operable now without the preamp? Have you seen/played it when the preamp was working? (I'm thinking someone may have had a good reason to take the preamp out, if you weren't the one who did that.)

And, is the goal to restore it to its original active wiring with the original preamp or just to get it working again with an active preamp?

Hi Newey, thanks for getting back to me here are some pics.  It did play when I bought but the wiring was a bit hack so I assume someone was already inside.   I would like to bring it back to stock first to see what it sounds like before I go out and buy a whole new wiring set and pick ups etc.   Here are some photos of the guitar and electrics. 

[mikecg]

Hello darryl,

I see that Riverhead are still around - but now based in the Philippines:

www.riverheadguitar.com/

You might try asking them for information (i.e. wiring diagram etc.) for your guitar:

[e-mail]

[newey]

mikecg's suggestion is better than anything I have to suggest. Can't tell much from the photos, unfortunately

When you say you played it at one point, was that with or without the preamp?. If the preamp was working at that time and you removed it later, we're probably safe in assuming that it is still operable. If the preamp was already removed, and given that you want to restore it to stock, you may need to do some testing to see if it is still working before you worry much about the rest of the wiring. I doubt someone would just remove the preamp if it was working. If the prior owner wanted a guitar with passive pickups, they probably would not have purchased a guitar with active pickups in the first place. So the likely scenario, it seems to me, was that it was removed because of issues with it.

[Yogi B]

Aug 13, 2024 11:28:03 GMT -5 newey said:

Can't tell much from the photos, unfortunately

I've not managed to fully trace the preamp, I can see enough to know the first op-amp of the dual is used as a fixed gain stage (with some filtering, though how much is impossible to say without knowing the component values). The second op-amp is used for a Baxandall tone control (or one of its many minor variations).

A lead from one of the green capacitors has become unsoldered — on the copper side of the board you can spy a solder spot with a hole through it, directly above the middle of the three B (= bass) pads — this would cause a lop-sidedness to the bass control, but wouldn't prevent the whole thing from working.

There's nothing as obviously wrong with the rest of the board, but from the one top-down photo of the component side I'm not entirely sure what is going on under the other green capacitor or the cluster of three capacitors near the IN (input, power & output) terminals. The dark blue cap appears to read 25, but as that's not a standard value I assume that's a voltage rating of what is presumably a tantalum cap, thus I think the input coupling cap. I think the adjacent aluminium electrolytic is part of the feedback divider for the first op-amp — as, I think, is the yellow cap. However I'm much less certain of that as I can't nail down where both of its solder pads are.

I'll post annotated version of the PCB, but it'll have to be tomorrow.

[stevewf]

Gonna need a schematic, I think, unless somebody can guess the components that were snipped off.


There might be others, those just jumped out at me.
[edit: Or are those just where the leads for the control pots went?]

[unreg]

B, G, and also T have been removed.  Perhaps T was wires.  And there's something missing perpendicular to T's middle dot.  And looks like there's a hole, where a wire went(?), in a solder spot perpendicular to B's middle dot.

edit:

Aug 13, 2024 13:23:39 GMT -5 Yogi B said:

A lead from one of the green capacitors has become unsoldered — on the copper side of the board you can spy a solder spot with a hole through it, directly above the middle of the three B (= bass) pads — this would cause a lop-sidedness to the bass control, but wouldn't prevent the whole thing from working.

Yogi B already found this hole… sigh, sry. Now, T must = treble?

[mikecg]

Hello darryl, newey, Yogi B, stevewf, & unreg,

Two things:

The opamp appears to be a fairly common or garden bipolar single supply wide supply voltage range device, is still readily available, and here is a link to the spec. sheet:

www.mouser.com/datasheet/2/294/NJM2904-221421.pdf

And here are the two views of the preamp pc board, with some image enhancement, and presented in a format that may help with tracing the circuit layout:

[Yogi B]

Aug 13, 2024 13:23:39 GMT -5 Yogi B said:

There's nothing as obviously wrong with the rest of the board...

I should have said other that the missing external connections.

Aug 13, 2024 17:33:03 GMT -5 unreg said:

And there's something missing perpendicular to T's middle dot.

I'm not sure: the pad is in the middle of a large ground pour which is an odd choice (lots of copper to conduct heat away from the solder joint). On the copper side there's two spots of solder: the smaller, rounder & more uneven blob is a splash, maybe from whoever added the yellow wire; the squarer smooth looking one is the one actually on the solder pad — but, while it does show a small imperfection in the centre, I'm unsure if that's because something has pulled out or if it's just because it's unpopulated.

Below is what I make of the preamp:

[darryl]

Aug 13, 2024 10:35:56 GMT -5 mikecg said:

Hello darryl,

I see that Riverhead are still around - but now based in the Philippines:

www.riverheadguitar.com/

You might try asking them for information (i.e. wiring diagram etc.) for your guitar:

[e-mail]

Hi Mike,
I emailed them first but sadly the email bounced back.  The company has unfortunately closed down.   

[darryl]

Aug 13, 2024 11:28:03 GMT -5 newey said:

mikecg's suggestion is better than anything I have to suggest. Can't tell much from the photos, unfortunately

When you say you played it at one point, was that with or without the preamp?. If the preamp was working at that time and you removed it later, we're probably safe in assuming that it is still operable. If the preamp was already removed, and given that you want to restore it to stock, you may need to do some testing to see if it is still working before you worry much about the rest of the wiring. I doubt someone would just remove the preamp if it was working. If the prior owner wanted a guitar with passive pickups, they probably would not have purchased a guitar with active pickups in the first place. So the likely scenario, it seems to me, was that it was removed because of issues with it.

From what I remember, as I bought this pre kids while I lived in Nashville and played a few times but noticed the sound was flaky and cutting out.  I opened it up and the preamp kind just fell out.   I can't remember if I cut it out myself to repair it or not.   My son has gotten pretty good on guitar and while visiting Montreal where the guitar was parked in my friends closet, we decided to bring to France where we live now and restore it so he has another guitar to mess with.  I have the same guitar but as a 4 string bass (passive) Just loved the sound and feel of it.  thanks for replying. 

[darryl]

Aug 13, 2024 15:24:24 GMT -5 stevewf said:

Gonna need a schematic, I think, unless somebody can guess the components that were snipped off.


There might be others, those just jumped out at me.
[edit: Or are those just where the leads for the control pots went?]

There is a white connector and flat cable (3 wires coming off one of the pots but not sure if that was connected to the white connector on the board. thanks for helping this is much appreciated.  I just got these messages now I guess I can turn notifications?     

[darryl]

Aug 14, 2024 8:18:51 GMT -5 mikecg said:

Hello darryl, newey, Yogi B, stevewf, & unreg,

Two things:

The opamp appears to be a fairly common or garden bipolar single supply wide supply voltage range device, is still readily available, and here is a link to the spec. sheet:

www.mouser.com/datasheet/2/294/NJM2904-221421.pdf

And here are the two views of the preamp pc board, with some image enhancement, and presented in a format that may help with tracing the circuit layout:

Hi Mike thanks for the image enhancement will make it easier to trace. 

[darryl]

Aug 14, 2024 8:51:14 GMT -5 Yogi B said:

Aug 13, 2024 13:23:39 GMT -5 Yogi B said:

There's nothing as obviously wrong with the rest of the board...

I should have said other that the missing external connections.

Aug 13, 2024 17:33:03 GMT -5 unreg said:

And there's something missing perpendicular to T's middle dot.

I'm not sure: the pad is in the middle of a large ground pour which is an odd choice (lots of copper to conduct heat away from the solder joint). On the copper side there's two spots of solder: the smaller, rounder & more uneven blob is a splash, maybe from whoever added the yellow wire; the squarer smooth looking one is the one actually on the solder pad — but, while it does show a small imperfection in the centre, I'm unsure if that's because something has pulled out or if it's just because it's unpopulated.

Below is what I make of the preamp:

Hi Yogi,  This very helpful.   I will take time this weekend to meter things out, eg pots linear or log etc and retrace the schematic and PCB and some notes and any corrections and upload them sunday or monday.   Thanks again.  Would it be easier if marked all the electronics and removed them from the guitar and prepare a proper wiring harness and then install when working again? 

[darryl]

Dumb question but what pots control what?   My buddy sent me this set up.  Do you guys think it could be similar?    

[mikecg]

Hello darryl,

That Nordstrand layout looks to be very suitable for your guitar. However, as your current set-up does not appear to have a push-pull switch, you will need to swap out the existing volume control for one with a push-pull switch - and that should not be too difficult. 
One more thing - the pickups look like active ones, but I'm wondering if they actually are? I can't see any sign of a power lead for the pickups, the shielded cables look like standard single conductor ones, so I'm thinking that they may be actually fairly standard passive pickups. If this was the case , the Nordstrand layout would certainly be suitable, as you would then be able to switch between active and passive modes, using the push-pull.
I would start by attempting to measure the DCRs of the pickups using a multimeter. If you get a sensible looking result, that will confirm that the pickups are indeed passive.
Then, it would be useful to measure their inductance - but you will need an LCR meter for that. Next, you should measure the resistance values of all the pots, and if there is any doubt about their functionality, now would be a good time to replace any that are suspect.

Once you have sorted the pre-amp, you should then be 'good to go' with The Norstrand hook-up.

[darryl]

Aug 15, 2024 6:52:05 GMT -5 mikecg said:

Hello darryl,

That Nordstrand layout looks to be very suitable for your guitar. However, as your current set-up does not appear to have a push-pull switch, you will need to swap out the existing volume control for one with a push-pull switch - and that should not be too difficult. 
One more thing - the pickups look like active ones, but I'm wondering if they actually are? I can't see any sign of a power lead for the pickups, the shielded cables look like standard single conductor ones, so I'm thinking that they may be actually fairly standard passive pickups. If this was the case , the Nordstrand layout would certainly be suitable, as you would then be able to switch between active and passive modes, using the push-pull.
I would start by attempting to measure the DCRs of the pickups using a multimeter. If you get a sensible looking result, that will confirm that the pickups are indeed passive.
Then, it would be useful to measure their inductance - but you will need an LCR meter for that. Next, you should measure the resistance values of all the pots, and if there is any doubt about their functionality, now would be a good time to replace any that are suspect.

Once you have sorted the pre-amp, you should then be 'good to go' with The Norstrand hook-up.

Was just discussing with my friend and he believes that the PCB I showed you all is the tone control part and the actual preamp part is missing...and I have a vague 2001 memory of have a cracked board with a 555 of all things, on it.  I will double check the case and see if I can find that part....it is the missing piece of the puzzle...if all this kina fails any recommendation for a prewired set up that I can order up? 

[mikecg]

Hello darryl,

One thing you will need to add to the Nordstrand hookup is the 3 way toggle switch, and that should be wired like this:

[newey]

Aug 15, 2024 8:20:55 GMT -5 darryl said:

..if all this kina fails any recommendation for a prewired set up that I can order up? 

If active pickups are the goal, you could just replace the whole thing with a pair of EMGs, or one of the cheaper clones thereof if the real deal puckers your pocketbook.

It's still not clear to me from the prior posts whether this thing ever actually worked passively, without the preamp, or not.. But I suspect mikecg is right, these are probably passive HBs with a preamp added "downstream". But your meter will tell the tale.

Also, given the apparent lack of replacement parts for this and the fact that you are already considering using a wiring diagram that may be "close" (but not exactly like the stock wiring), plus with the question marks about the preamp, it may be time to reconsider whether it is worthwhile or practicable to try to bring this back to its original stock configuration, or to modify things to make it to your liking (or your son's liking, as you said it was t be a spare for him). If it's not going to be original anyway, do whatever you want to get it playable and don't worry about originality. 9 VDC preamps abound, and it's probably easier on your stress level to just forget about trying to repair the original, and invest a few dollars to keep your frustration level down to a low simmer.