[ 'Dead CRATE BV- need help! ]

[Steve Conner]

Well, it would be very easy to remove TR1 to see if that made a difference. It's not needed for normal operation, it is just to protect the rest of the circuitry if one of the tubes develops a heater-to-cathode short.

[Sea Chief]

Chaps.

Erm.. what/ where (this is to see who is awake, I hasten to add) is a TR1?

[gtrplayr1976]

Chaps.

Erm.. what/ where (this is to see who is awake, I hasten to add) is a TR1?

I have a picture location somewhere. I'll see if I can find it ,and post it. It's near the F6 fuse.

[Sea Chief]

I have a picture location somewhere. I'll see if I can find it ,and post it. It's near the F6 fuse.

Got it- v helpful that. (looks a like a BV of sorts?).

So is looks like a heavy-duty diode is it? And in business side of the amp here.. either side of it likely to be tied up to any bigV caps? (Im trying to find it on schematic).

[gtrplayr1976]

Got it- v helpful that. (looks a like a BV of sorts?).

So is looks like a heavy-duty diode is it? And in business side of the amp here.. either side of it likely to be tied up to any bigV caps? (Im trying to find it on schematic).

If you have the 105XXH1 Schematic look toward the bottom at the filament taps. As long as you have the power off ,and the caps have drained it should be fine. Copied the below.


The SIDAC is a silicon bilateral voltage triggered switch with greater power handling capabilities than standard DIACs. Upon application of a voltage exceeding the SIDAC breakover voltage point, the SIDAC switches on through a negative resistance region to a low on-state voltage. Conduction will continue until the current is interrupted or drops below the minimum holding current of the device

[Sea Chief]

Ok gtrP.. TR1 is out. Godam has no polarity marking on like the board diagram under it.. but Im fairly sure which end goes back etc. Cant find on schematic but not to worry for now.

Ok so Im turning on again/ testing etc.. just without TR1 in at all?

[gtrplayr1976]

Ok gtrP.. TR1 is out. Godam has no polarity marking on like the board diagram under it.. but Im fairly sure which end goes back etc. Cant find on schematic but not to worry for now.

Ok so Im turning on again/ testing etc.. just without TR1 in at all?

Yeah ,it should be fine. There's schematics on here somewhere. Let me correct something. This actually isn't off the filament ,but off the 6v taps. I think the SIDAC will work either way you install it.

[Sea Chief]

Yeah ,it should be fine. There's schematics on here somewhere. Let me correct something. This actually isn't off the filament ,but off the 6v taps. I think the SIDAC will work either way you install it.

(Steve- thoughrally contact-cleaned FS socket, & FX send/rtn too > tested before moving onto gtrP's suggestions here. No joy. Thx tho).

Got that gtrP. Ive found schematic.. but a pesky sod to find TR1 on it.

Ok here goes. If it goes pop then hey.. its going in the river anyway by all accounts!

[Sea Chief]

Done/ tested with TR1 removed: noise remains.

[gtrplayr1976]

(Steve- thoughrally contact-cleaned FS socket, & FX send/rtn too > tested before moving onto gtrP's suggestions here. No joy. Thx tho).

Got that gtrP. Ive found schematic.. but a pesky sod to find TR1 on it.

Ok here goes. If it goes pop then hey.. its going in the river anyway by all accounts!

Well if it pops it won't be because of the SIDAC being removed. I know this is frustrating ,but there has to be a remedy for it.

[gtrplayr1976]

Done/ tested with TR1 removed: noise remains.

Damnit. Well I knew it was a long shot with that type noise. Wish I were closer ,so I could try to help.

[Sea Chief]

Well if it pops it won't be because of the SIDAC being removed. I know this is frustrating ,but there has to be a remedy for it.

Exactly. It must be something. And likely one thing. Shame about the SIDAC but worth a go: any suggestion is welcome. I just dont have any expectations now! theres no point taking to a tech surely (where/ who Ive no idea anyway.. as theyd spend 2 hrs doing all the same tests/ £40 per hr.. sigh).

(I just counted 37 components Ive replaced. 37! Irrespective of the 7 different tubes, all manner of removals/ short tests, jumper tests etc etc.. & still the exact same godam noise as day I got, it 8 weeks ago! sheesh blimey :-)

[gtrplayr1976]

Exactly. It must be something. And likely one thing. Shame about the SIDAC but worth a go: any suggestion is welcome. I just dont have any expectations now! theres no point taking to a tech surely (where/ who Ive no idea anyway.. as theyd spend 2 hrs doing all the same tests/ £40 per hr.. sigh).

(I just counted 37 components Ive replaced. 37! Irrespective of the 7 different tubes, all manner of removals/ short tests, jumper tests etc etc.. & still the exact same godam noise as day I got, it 8 weeks ago! sheesh blimey :-)

One of my friends has one that I have worked on ,but didn't have that issue. It will be with me again soon as it has another issue. I also have another Crate at the house I'll be working on too. A VC 5310. I have a BV50 myself ,but I seldom use it.

CRAP...just noticed this is a BV50 ?

[gtrplayr1976]

Have you been testing with the reverb disconnected ? Have you checked the FX loop ? These may not have anything to do with the noise ,but I know they can cause issues in other amps. Wish you had a sound clip of the noise. When I think crunch I think good sound

[Sea Chief]

Yes indeed it is. A head version, older blue tolex type. Nasty lookers tbh. And the mini-pots are bad plastic. But I like.

One last thing Ive not ruled out is a bad MV pot itself (250k Lin). Can I sub in a 10k A to test? (only mini one I have to fit).

I was even thinking of asking crate if there's any chance of a pcb I could buy.. & Id take a week and shift the lot over to that. It can only be the V2 socket now afaict (a bitch to rplace/ cant find the same type so not worth it)... or a pcb track contamination thing you see/ my last gasp.