Estimated date of my Tremoverb

[mixtery]

R-011666. (evil)

Would this have the suspect LDR's?

 

[jazzblaster]

Hmm,

i would guess its a 97-98 and yes your ldr's are bound to fail but you may be lucky.

My t-verb is an early 96, serial is in the 9XXX and so far 4 ldr's failed on me!

hope it helps

 

[mixtery]

Thanks so much I've had the amp for a lot of years and it went down twice on me during gigs.
It seems to be ok for about 30 mins of playing time then suddenly a loud noise comes on while playing. Something warming up and getting too hot maybe? I'm thinking of sending it back to boogie for an overhaul. What do you think? Is there a DIY somewhere on how to change the LDR's I'm pretty handy with the soldering iron.

 

[jazzblaster]

Thanks so much I've had the amp for a lot of years and it went down twice on me during gigs.
It seems to be ok for about 30 mins of playing time then suddenly a loud noise comes on while playing. Something warming up and getting too hot maybe? I'm thinking of sending it back to boogie for an overhaul. What do you think? Is there a DIY somewhere on how to change the LDR's I'm pretty handy with the soldering iron.

Well the t-verb is a pretty unique amplifier so yeah, i would definetly go for the overhaul. Thats what i did.

Any good amp tech can change ldr's and its a cheap repair! Or if you dont mind sending it, Mesa is doing it for free!

Is there a DIY somewhere on how to change the LDR's - Maybe 94tremoverb can help you on this one

 

[70 Cam Guy]

My born-on date for my head is June '94. I was thinking of taking mine to a tech for a checkup/tuneup (if there is such a thing). I half considered just driving to Petaluma with it. It even still has the old 6L6's with STR-430 part number

I tried searching Google for LDR, but it referenced a light-dependent resistor, or photo resistors. I can't picture where photo resistors would fit into a tube guitar amp. I wouldn't be surprised if this is in a sticky here, but I haven't seen what LDR stands for in relation to our Tremoverbs. I found here they are used in the channel switching, and bad ones can disable the Tremolo. Other than that, what type of symptoms might alert me to bad LDR's? It seems like there are many. I haven't used the tremolo in a long time... *ducks*

 

[94Tremoverb]

Technically the "LDRs" are actually opto-couplers - a LDR and a LED in the same package. They are used as switches at multiple points in the circuit to change "channels" and modes. The amp does not actually have separate channels, it's all the same channel but with two different control networks and voicings that are switched in and out by the LDRs. The tremolo does also use one, but it is only one - there are 25 overall! All of them are probably destined to fail eventually, the chemical material in the LDR degrades over time (it's always the LDR side that fails). It may be heat-related, as the Tremoverb combo seems particularly prone to it, the Tremoverb head less so, and the MkIV (which uses almost as many) much less so - but it runs a lot cooler.

Symptoms are if one of the channels or functions (eg reverb) stops working, or if it doesn't sound right or respond correctly to switching.

Changing them is fairly straightforward if you're good at fine PCB soldering work. (Not fine by modern electronics standards, just fine by tube amp standards!) If anything, in many cases it's easier to change them all at once as most are stacked in multiples, and it always seems to be the one at the bottom that has died . Each one has four leads and they must be got the right way round.

Make sure you get the correct spec too - they vary by voltage, on and off resistance, and switching speed. The speed is especially important, if you use the wrong type the amp will do odd things as it switches, like a momentary surge in volume. (This is a slight problem anyway, when switching from some settings to others.)

 

[70 Cam Guy]

Wow thanks for the great insight on those! Very much appreciated

I'm getting some unusual sounding distortion on the blues voicing. Hard attacks on the strings I get some clipping through the amp. It doesn't sound like good breakup, more like microphone clipping. I haven't had a chance to test other gain settings so I'm not sure if that is just the nature of the blues voicing or if something else is going on. I have the gain set very low to be in between clean and pushed tones, very responsive to volume knob adjustments. I imagine if its in between voicings or not completely switched, maybe that extra signal could be causing problems.

I've had electronics classes before and made a couple diy stomp boxes, so soldering doesn't scare me. Parts sourcing would be more concerning than anything else.

I definitely see what you're talking about. The stacked components with 4 leads are pretty obvious in the photo I took of my board

by AYates Photos, on Flickr

 

[nyeguy]

I currently have 2 Tremoverbs down with LDR issues! One a '94 combo that I bought new and a '99 head that I bought last January. The 99 has the bad batch of LDRs and lost the red channel at a gig last month and the 94 lost its reverb first, then the orange channel. My question is directed to 94tremoverb... Where is a good source for buying LDRs? Im going to replace all 50 in both amps! I cant live without my t-verbs and cant have em going down at gigs! Im using my "backup" Roadster now... Not a bad backup huh? Its an awesome amp but there's magic in those t-verbs! HELP!

 

[mixtery]

I currently have 2 Tremoverbs down with LDR issues! One a '94 combo that I bought new and a '99 head that I bought last January. The 99 has the bad batch of LDRs and lost the red channel at a gig last month and the 94 lost its reverb first, then the orange channel. My question is directed to 94tremoverb... Where is a good source for buying LDRs? Im going to replace all 50 in both amps! I cant live without my t-verbs and cant have em going down at gigs! Im using my "backup" Roadster now... Not a bad backup huh? Its an awesome amp but there's magic in those t-verbs! HELP!

that's a lot of LDR's! I do think I need to replace mine but I think I have another problem with the huge noise burst coming through my amp. I think it's going back to Mesa for a full overhaul... if I can easily get it out of the combo for shipping. These amps are awesome live but I won't gig without a second amp again.

 

[94Tremoverb]

My question is directed to 94tremoverb... Where is a good source for buying LDRs?

I got mine from Mesa's UK distributor (since I'm there). If you're in the US or Canada, probably contact Mesa directly. They may not be the cheapest option but you know for certain you're getting the correct ones.

These amps are awesome live but I won't gig without a second amp again.

Actually that's one of the reasons I like them - OK, you may have to restrict what you can do with them (down to one channel probably) but there is very little that can go wrong with one that would leave you without a workable amp. There isn't an LDR failure I can think of that would leave the amp inoperable on at least one channel; it has both tube and solid-state rectifiers (fully switched, unlike the 3-channel Rectifiers) so a failure of either can be got around by flipping the switch; four power tubes so you can run it on two if you have to; with one spare 12AX7 (or borrow the FX loop one if you don't need it) and a few fuses you can survive almost any failure without carrying a spare amp. About the only thing that would stop it totally dead would be a blown transformer (which I've never seen on any Mesa) or a failure in the low-voltage supply or bias supply, which is also very rare to unheard of in Mesas. It might take a few minutes but I'm confident enough that I could get it going again that I don't carry a spare amp. (Although I do still have a last-ditch pedal-into-the-PA backup.)

 

[mixtery]

My question is directed to 94tremoverb... Where is a good source for buying LDRs?

I got mine from Mesa's UK distributor (since I'm there). If you're in the US or Canada, probably contact Mesa directly. They may not be the cheapest option but you know for certain you're getting the correct ones.

These amps are awesome live but I won't gig without a second amp again.

Actually that's one of the reasons I like them - OK, you may have to restrict what you can do with them (down to one channel probably) but there is very little that can go wrong with one that would leave you without a workable amp. There isn't an LDR failure I can think of that would leave the amp inoperable on at least one channel; it has both tube and solid-state rectifiers (fully switched, unlike the 3-channel Rectifiers) so a failure of either can be got around by flipping the switch; four power tubes so you can run it on two if you have to; with one spare 12AX7 (or borrow the FX loop one if you don't need it) and a few fuses you can survive almost any failure without carrying a spare amp. About the only thing that would stop it totally dead would be a blown transformer (which I've never seen on any Mesa) or a failure in the low-voltage supply or bias supply, which is also very rare to unheard of in Mesas. It might take a few minutes but I'm confident enough that I could get it going again that I don't carry a spare amp. (Although I do still have a last-ditch pedal-into-the-PA backup.)

I've had questionable power in small clubs here in Brooklyn cause my amp to go down twice. It would not turn back on and the transformer was fine. The first time it blew a speaker, two power tubes, and fried some resistors. I find these amps are very sensitive to house power. Where as I've had a Marshall JCM800 that's lasted 20 years without an issue. 100's of gigs I'm talking. I mean any tube amp is prone to these types of things, but the Mesa's are pretty complicated amps compared to most.

 

[94Tremoverb]

I agree that the JCM800s (the non-channel-switching ones particularly) are some of the most bombproof amps ever made. Shame more recent Marshalls aren't, or I'd probably still be playing them. I can still remember looking inside a dead JCM900 for the first time and thinking WTF is this?! Although even those are better than the 2000s.

My experience with Mesas is that they're some of the most reliable amps out there, although it is true that we have much more consistent power here in the UK than in some parts of the world. Some freaky power issues you have in Brooklyn! Tubes and resistors going I can understand, but blowing a speaker is almost impossible for any kind of power problem on a tube amp, even a massive over-voltage. If it's that bad I'd be a bit concerned about my own safety, let alone the amp...!