Rockmaster preamp - relays

[johnylondon]

Hi all, I'm new here and it's my first post - but I'm not new to Peavey anyway!

I bought a Rockmaster preamp back in the day, and though it sounded great, reliability problems (it had to go back to the shop a couple times with relay trouble) and no midi eventually saw it sat idle as an ADA became my gigging companion for many years.

Anyway... I recently fired up the Rockmaster, and was amazed at how it blew away the ADA - it's just SO clear and SO crunchy (on max distortion I mean! And incidentally gives me a sound very similar to what Metallica are using these days). So, I have decided to upgrade my fx unit to a G Major so I can once again use the Rockmaster (allowing me control over channel selection, at least).

However, it's back with its "old trouble" - sometimes you can hear relays randomly switching as it warms up, and it takes half an hour for the most distorted channel to come through properly. The clean is just not working at all.

Getting there now... so what I would like to know is - where can I get replacement relays? I can see the two that the shop must have changed (they are orange, and Japanese) and the six white original German made things - so I presumably have there a choice of a couple different suitable parts. Also, as the German relays show the pin outs, I could trawl through RS or something.

However - thought it might be worth a shot here - maybe someone has a link straight to these little beauties? I plan to swap out all 8 while I'm at it - though if anyone can easily tell me which relay does what I might just do what is needed right now. (I have the schematic but found it hard to read).

I was pleased to see how well respected these preamps are when I started googling recently - oh and by the way - I know about the problem with the sends/returns - don't think it's that.

Thanks in advance.

[johnylondon]

Sorry to reply to my own thread but I see there have been plenty of views...

I have discovered that infact, the six white relays have different pin outs to the two orange ones, so no idea which relays were changed by the shop, years back.
By different I mean that where the white ones use pins 1, 4, 6, 8 and 9, 11, 13, 16, the orange ones use pins 1, 3, 5, 8 and 9, 12, 14, 16.
Having looked online I have found that indeed dil relays can be readily found in either configuration, with the two pins that are away from the rest invariably being the actuator itself (some with polarity, others not... guess there is a diode across the coil in some). However, the other sets of pins don't always have the same common pin. Well, as the white relays have a drawing ontop showing the connections, that is quite easy to find a replacement for, but the orange ones not so.
I contacted Peavey who gave me a part number and a phone number so phoned up (USA) to inquire. Currently there is no uk distributor and the usa can't send parts to the uk - at least not to individuals. However, they did mail back with a uk number and a little more info - price (5 quid each plus vat plus shipping) and the fact that they are now specified as Omron parts.
That set me thinking - armed with the info that they are now using Omron, and knowing the pinouts for the white ones at least, I soon found suitable parts available both on ebay and Farnell, as well as possibly Cricklewood Electronics the Farnell were quite competitive. Don't know what to do about the two orange ones though - and indeed I don't know which relays switch what.
The part I found that I think will replace the white ones is G5V-2 12Dc - anyone know anything?

I'll update when I get this resolved

[johnylondon]

Update:

Peavey sent me a picture of the relays to use as replacements - Omron G6A-274p-ST-US

As Peavey uk wanted a fiver a piece plus delivery, I sourced the exact same part from a company called tme.eu - £22 for six including delivery I don't know about the other two relays (the orange ones).
The new parts were here fast - and I got them fitted. The preamp is working correctly now BUT I have really bad thumping when switching channels

There's still the caps to change, as the thing hums a lot too

Nice sounds though

[The_Chris]

I know this is an old thread - but - I'd like to pick your brain if you're still around. I'm in the same boat. Great preamp, but it takes time for the crunch channel to be operational, and now, it seems to peter in and out.

Did you ever identify THE relay for that channel? Or did you replace all of them?

Thanks.

[KTB]

Your chances of that guy showing up here are almost slim and none since the last time he posted was 2014. You could maybe email as his address if still good is under his name if you click on it. May want to do what he did and change those relays and check all the switching JFET's that are associated with that network.

[Enzo]

Before you throw relays at it, try bridging each FX loop in turn, using a spare guitar cord. Especially the loop jacks for that channel. Dirty return jack cutout contacts are quite common in any amp with an FX loop.

[johnylondon]

Hi Chris,
Hey presto here I am

As I said, I changed all the relays (except two I think that were different) and that sorted the problem. Infact they were changed once when the thing was nearly new - unfortunately for me it's been this units weak spot.
The "thumping" I mentioned when changing channel soon disappeared - prolly just oil on the relay contacts, and its worked ok since - with one exception - sometimes I have to turn the gain (on the high gain channel) right up for a second to "blast" the sound through.
I tried the thing with the fx loop jacks, they have never been a problem as far as I know (unless that's what this latest symptom is).
As far as which relay does what I'm afraid I don't know - but I do have a paper copy of the circuit diagram, only I can't get access to it now as it is somewhere else. Peavey might help with that?
A great pre amp but I've not found it reliable. Wish they did a midi version.

[Enzo]

Turning up to blast it back to full volume is a classic symptom of dirty loop return jack cutout contacts.

[johnylondon]

oh, maybe it's got that as well now - but it was definitely the relays before. I'll do the thing with a patch lead and some switch cleaner next time.

[Riffraff12571]

I wonder why they chose the G6A-274P-ST-US-DC12 relays instead of the G5V-2-DC12 relays. The G5V-2-DC12 relays are actually a closer match spec wise to the original P&B relays. Both of those have bifurcated gold flashed contacts, have the exact same contact ratings with the low current rating being particularly important, they both have the same current draw and both are designed for use in audio circuits. I'm planning to replace my relays this weekend and bought the G5V version to do the work because they match the original P&B relays exactly. I happen to have an old P&B catalog at work and used that to select a match. Now I'm wondering if I'm making a mistake in using them.

[Enzo]

Just my opinion, but that sounds like overthinking.

When I hear the symptom is relays clicking on and off at random, that frankly does not sound like a relay problem. SOmething controls the relays, something provides current for them to energize.

On these units, by far the most problematic parts are the jacks. The cutout contacts in them are used by the circuits, and they become electrically dirty. The relay control circuits work directly from the footswitch jack. Pulling the boards and doing solder work also puts mechanical force into the jacks. often just taking the thing apart and putting it back together will clear a problem...for a while.

In my experience, cleaning and burnishing all the cutout contacts in all the jacks cures 99% of the problems presented for repair.

[Riffraff12571]

Thank's for responding Enzo. I cleaned all the jacks with Deox and a small spiral brush first then did the pots. The seller I got mine from had 3 of them. The 2 better one's were in his rack and this one, which appears to have been used a lot at one time, was his unused parts donor. It was in storage and only pulled out to provide replacement knobs and rack ears for the other 2. This being the case I assumed all jacks and pots were dirty and cleaned them as soon as I got it home. I don't have random switching, I have a contact quality issue. It seems like there may be one or more relays with worn or oxidized contacts. When I first turn it on often there is no sound or a crackly weak tone like I'm using a bad cable. Cycling the power off and on causes some of the relays to change state as voltage is removed from the relays coils then reapplied. This switching will usually clear it up and it will function normally. I'm not sure which one is doing it and figured I would just replace them all since I experienced similar switching type issues when trying to switch channels with a 2 button Peavey foot switch.

[johnylondon]

Just to let you all know I'm still around!
It's unfortunate that these pre amps seem prone to such problems, as the sound is awesome. By contrast my (far more complicated) ADA performed flawlessly for many years and is still going strong.
I've not tried using the Rockmaster for a few years now but will doubtlessly get curious and hook it up again one day.

[Enzo]

Just a thought. When I refer to cleaning the jacks, this is not something you can do from outside. I am not talking about the contacts that touch the inserted plug. I am talking about the side contacts that open and close from the plug action.

Inside the unit, look at the jacks, see the contact strips crosswise to the plug. Push a plug into a jack and see it lift that blade up, parting it from the contact underneath it. THAT is what must be cleaned. I have a special burnisher for this, but I also sometimes clip a sliver off the end of a business card, and use it. I push in a plug to lift the blade, insert my piece of card, and remove the plug. Now my paper strip is pinched in the contacts. A gentle back and forth motion wipes the contacts clean.

[johnylondon]

Doubtless mine'll need a bit of tlc when it does come out again - will keep this tip in mind!