Roland Bolt 60 reverb tank?

[Trick]

Hi I am having problems with the reverb in a Roland Bolt 60 combo amp. I want to replace it, but am having trouble finding a drop in. I looked for information everywhere but the only thing I found was accutronics 8ab3c1a. I don't think this model exists. I emailed accutronics and received information that Belton has bought them, so were unable to help me. I did not receive any information back from Belton. I noticed this model 8ab2d1a for a JC120 and it may work, anyone know?

Also, if anyone has had experience with this amp. I was using the overdrive channel and it would work for about a minute and then cut right out on me. I would have to switch back to clean. I would switch back to the od again but it would do the same thing. As if something was overheating.

thanks for the help

[Jazz P Bass]

Roland Reverb Tank

Are you sure that there is something wrong with the Roland reverb tank?
There are two coils on the tank. An input and an output coil.
Look to see that the red & black wires are secure to each RCA jack.
Try to measure the DC resistance of each coil.
The input coil should read lower than the ouput coil.
If you have coil resistance & the springs are secure, the tank may be o/k.
Where did you come up with the Accutronics number "8AB3C1A"?
Is that what the Roland tnak number is?

[Trick]

thanks for the reply. From what I remember, it sounds like the reverb is breaking up, like a crackling. When reverb is off it sounds fine. I will look into measuring the resistance. here's where someone has listed that particular model number: Roland Bolt 60

[Jazz P Bass]

Roland reverb

What a cool web site dedicated to the Roland Bolt.
So now you have the schematic.
I would start by looking at the outputs of IC 2.
Pin 1 / reverb drive
Pin 7 reverb recovery
With your DVM set on Vac you should be able to "see" the crackle.
You have to narrow down which part of the circuit is at fault.
There are some fine voltages labeled on the schematic. Check them.
Do a check on the signal diodes & the transistors.
It may end up being a capacitor.
Happy Hunting.

[Jazz P Bass]

REVERB TANK

the only thing I found was accutronics 8ab3c1a. I noticed this model 8ab2d1a for a JC120 and it may work, anyone know?

The reverb tank 8AB2D1A has the sane input & output coils as the one recommended on the Bolt web site. it is also an 8" tank.
So far, so good. That is the first 3 (8AB)
The {2} indicates a medium decay time
(3) is a long decay.
What may or may not be a problem is the next letter. (D)
(D): input connector insulated from tank/ output insulated from tank.
The tank from the Bolt site recommends a (C)
(C): input connector insulated/ output connector GROUNDED to tank.
Looking at the schematic, both coils appear to be grounded.
So this may not be an issue.
That leaves the decay time.

[Trick]

thanks again for the help and for translating the schematic. I'm not too proficient in reading them. Good to know that it should work. How do I check the diodes, transistors, and capacitors with a dvm? Or if its a lengthy explanation, is there another place that explains how to do this and what results I would be looking to find. Is this how I would see the crackle, if one of these components are at fault?

[Jazz P Bass]

Crackle

I suggested looking at the IC with your DVM set on Vac. One lead to chassis ground, the other lead to the test point.
You need a signal source.
Have somebody play or hook a cd player to the input jack.
The crackle should show up as a higher signal level than no crackle.
You really need a signal generator & a scope.
The best way to check a diode or transistors is with a DVM that has the diode check symbol.
A diode will show a reading of around .650 with black on the striped end, red on the other end.
Transistors basically check the same.
Google it.

[Enzo]

Look at the output pin of the recovery IC. Is there DC voltage sitting there? If so, try a new IC.

[slick picker]

I had the same trouble with my reverb tank. When they get old, they just get really sensitive and touchy and the least little thing will cause them to crash and rattle: mine was so aged that whenever I played a note, it would crash in the background. Bummer. So I went hunting for a replacement for the original tank (OC no longer made). I dropped in an Accutronics short reverb tank that works fine on my Bolt 60. First, I tried an 8E series (what goes into a lot of small Fender amps like the Blues Jr.), but the impedance was too high (around 800 ohm). So I tried an 8B unit, and it works like a charm (10 ohm). Hope that helps.