Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Hoodnight on November 28, 2021, 08:37:07 pm

Title: Ibanez TSA5-TVR reverb cutting out
Post by: Hoodnight on November 28, 2021, 08:37:07 pm

Currently working on a friend's Ibanez TSA5-TVR. Cute little TV front amp with a built in Tubescreamer, seems like a similar circuit to the TSA5 but has op-amp driven spring reverb added.

Friend dropped it off after purchasing, said that the reverb wasn't working. Opened it up, tested the cables for continuity, sprayed the connections, et voila, reverb is working again.

Put it back together, set it down. The day before I return it, I try it out for fun, and the reverb has stopped working again.

Open it up, test it, reverb works again. Cue confusion.

I can get it to consistently cut out with some percussive maintenance. Facts are as follows:

• Hitting the cabinet (with the tank inside) with the amp chassis isolated from the shock causes the reverb to cut out.
• Hitting the amp chassis with the cab & cab isolated from shock does not cause the reverb to cut out.
• After the reverb has cut out, immidiately power cycling the amp restores the reverb.
• Connection cable is all OK.
• Ground connections for the reverb circuit are all OK.

My best guess is that the tank is faulty - there are quite a few reports of this amp having dodgy reverb, and the tank itself appears to not be available anywhere. The tank is an Accutronics N1EB3C1B.

If this were faulty, would a 8EB2C1B be a viable replacement, or would the higher impedances in the Type 8 tank be an issue?

Otherwise is there something else that I could be missing?

Cheers.

Title: Re: Ibanez TSA5-TVR reverb cutting out
Post by: uki on November 29, 2021, 10:06:10 pm

Intermittent problems are the hardest to find, before replacing the reverb tank, check it if there is anything loose, check for continuity in the springs, check the reverb circuit for bad solders, and so on.

Schem attached

Title: Re: Ibanez TSA5-TVR reverb cutting out
Post by: Hoodnight on November 30, 2021, 06:21:22 pm

Thanks uki. Nothing looks untoward after testing apart from one spring having continuity with the mounting bracket and one not. What should actually have continuity here?

Title: Re: Ibanez TSA5-TVR reverb cutting out
Post by: uki on November 30, 2021, 06:53:30 pm

All springs should have connection between its ends. A loose wire on that spring maybe? or loose bolt? its probably possible to fix it, find the point where the connection is severed. Could you post some photos please?