Guitar Effect Repair...

[BTF]

Hope this doesn't violate any forum rules! If so please remove the post.

A friend recently gave me a Ross Analog Delay (the yellow on black, Taiwan model). It works perfectly except for an odd faint harmonic/distortion which is only occurring in the delayed signal. I'm figuring a cap in the companding circuit is faulty.

I'd like to get it repaired. Normally I'd try it myself, but quite honestly I've got more pressing personal matters on the stove than I can handle right now and don't have time at all for a delay (pardon the pun!).

May I ask, can any of you recommend a reputable repairman who handles analog delays? I've Googled several fellows, but I've never dealt with any of them. I had a camera shop in Tempe, AZ wreck a nice old Canon several years ago, so I'm wary of just sending it out willy nilly. I value you fellow's opinions!

Thanks, Bill.

[tele caster]

Does it look like the pedal in the links?

http://www.effectsdatabase.com/model/ross/r80

http://www.freestompboxes.org/viewtopic.php?f=19&t=1018

[BTF]

Yes. V3, the black one with the yellow square is identical to the one my friend gave me. However, mine is the version right after Ross moved production overseas to Taiwan. The Korean apparently came after Taiwan. My friend's had this for years. He's a reformed metalhead turned bluegrasser and hates effects now...

Those prices in that link are startling!

I tried this thing late last night. The preamp in this thing is quite impressive! I thought the EP3 preamp was great. The Ross really improves the clean tone of whatever plugs into it!

Currently, I just don't feel like working on it. I haven't been feeling up to par physically (getting older is the pits) and would probably make a muck of it.

It has a high harmonic, like a bad harmonizer, in the delayed signal. I'm fairly certain the problem is a faulty cap in the compander circuit. I would rather just let someone else do it.

Regards, BTF.

[BTF]

It's interesting. In that thread you posted a fellow mentions signal loss when the effect is used mono. I've looked at the circuit. The main reason for the loss is the summing/mix circuit the Ross uses. It works much like the later Peavey Valverb. If you turn the mix to dry, there's no signal loss from bypass.

It's design is unusual. Ross essentially gave you a mix control for each amp. One footswitch just shunts the signal to ground for amp 2. The other switch turns the effect on and off for amp 1. In stereo the thing is quite staggering. You can set one amp to have a stronger delay so that the second amp seems to echo the first.

I basically just plan to use it for a rockabilly slapback.

[briane]

whehhh!- lots of chips in that sucker - have an IC list?

haha - sometimes they burn out when Ive repaired other brands of fx.

look for the black burn mark! - actually often a solder joint they missed - or came loose. start with the inspections and look around inside for a while.

never been inside one of those though - just got a killer ape delay in a sweet trade though!

-b

[tele caster]

I'm not really familiar with that pedal but I have built a few analog delays and most of them clip at longer delay times. They can be calibrated for a fairly clean signal by adjusting the trim pots, but not totally. Are you getting a clean signal at shorter delay times? Changing the electrolics might be a good idea for a 30 year old pedal.
You might be able to tweek it yourself by ear. Turn your delay and recycle half way up and the mix pot 1/4 way up. Locate the bias trimmer inside and adjust for the cleanest signal.

One word of warning, the delay chips SAD1024 are static sensitive and obsolete. Make sure you and the pedal are grounded if you're going to touch the insides. Even a spark from a carpet can fry them.

http://www.dirk-hendrik.com

Dirk might give you some info.

[BTF]

Thanks truly for all the advice! As to my servicing this, I'm afraid I'm just not up to it at the moment. I don't think I'd want to change a light bulb!

As to the problem, the harmonic appears during short or long delays. I'm fairly certain the problem is in the companding circuit. There are quite a few chips in there. 3 SADs as tele pointed out, several 4558s, at least 1 or 2 compressor/expander chips.

The layout is fairly neat. It has that enamel covered board which begins to shed its enamel after a few years. There is a bit of the ground plane visible at the edge. I'm fairly certain that's not the problem, though. It'll be a nice delay if I get it right.

Who knows, I may decide to tear into it if none of my email contacts pan out. I emailed Analogman, an FX Repair in Boston and someone else whose name I can't recall. I hate to send it off as my camera experience was a nasty and expensive one. Yet, no one local to me does this.

Thanks again for the help and concern! Bill.

[DonMoose]

It has that enamel covered board which begins to shed its enamel after a few years. There is a bit of the ground plane visible at the edge. I'm fairly certain that's not the problem, though.

If it's transparent-ish it's this stuff called Conformal Coating, and is supposed to protect sensitive hi-Z inputs and touchy timing circuits from moisture/humidity-related leakage currents.

1) scrape that crud off the pad and component before you try to solder.
2) re-coat any scraped or peeled areas near those sensitive spots I mentioned.

- hope this helps!