diff --git a/docs/api_TDEM_derivation.rst b/docs/api_TDEM_derivation.rst
index 364070e5..0d8bfcea 100644
--- a/docs/api_TDEM_derivation.rst
+++ b/docs/api_TDEM_derivation.rst
@@ -255,25 +255,8 @@ Multiplying **J** onto a vector can be broken into three steps
         \vec{p}_e^{(n)} = - \diag{\e^{(n)}} \Ace \diag{V} m
     \end{align}
 
-First time step
 
-.. math::
-
-    \begin{align}
-        \frac{1}{\delta t} \MfMui \vec{y}_{b}^{(1)} + \MfMui \dcurl \vec{y}_{e}^{(1)} = \vec{p}_b^{(1)} \\
-        \dcurl^\top \MfMui \vec{y}_b^{(1)} - \MeSig \vec{y}_e^{(1)} = \vec{p}_e^{(1)}
-    \end{align}
-
-
-.. math::
-
-    \begin{align}
-        \left( \MfMui \dcurl \MeSig^{-1} \dcurl^\top \MfMui + \frac{1}{\delta t} \MfMui \right) \vec{y}_{b}^{(1)} = \MfMui \dcurl \MeSig^{-1} \vec{p}_e^{(1)} + \vec{p}_b^{(1)} \\
-        \vec{y}_e^{(1)} = \MeSig^{-1} \dcurl^\top \MfMui \vec{y}_b^{(1)} - \MeSig^{-1} \vec{p}_e^{(1)}
-    \end{align}
-
-
-Remaining time steps:
+For all time steps:
 
 .. math::
 
@@ -295,6 +278,11 @@ and
         \vec{y}_e^{(t+1)} = \MeSig^{-1} \dcurl^\top \MfMui \vec{y}_b^{(t+1)} - \MeSig^{-1} \vec{p}_e^{(t+1)}
     \end{align}
 
+.. note::
+
+    For the first time step, \\\(t=0\\\), the term: \\\(\\frac{1}{\\delta t} \\MfMui \\vec{y}_b^{(0)}\\\) is zero.
+
+
 
 
 Implementing **J** transpose times a vector
diff --git a/simpegEM/TDEM/TDEM_b.py b/simpegEM/TDEM/TDEM_b.py
index 2999f01e..e60b9ec9 100644
--- a/simpegEM/TDEM/TDEM_b.py
+++ b/simpegEM/TDEM/TDEM_b.py
@@ -52,7 +52,7 @@ class ProblemTDEM_b(BaseTDEMProblem):
         p = self.Gvec(m, v, u)
         y = self.solveAh(m, p)
         Jv = self.survey.projectFieldsDeriv(u, v=y)
-        return mkvc(Jv)
+        return - mkvc(Jv)
 
     def Jtvec(self, m, v, u=None):
         if u is None:
@@ -117,19 +117,20 @@ class ProblemTDEM_b(BaseTDEMProblem):
         return p
 
     def solveAh(self, m, p):
-        def AhRHS(tInd, u):
+
+        def AhRHS(tInd, y):
             rhs = self.MfMui*self.mesh.edgeCurl*self.MeSigmaI*p[:,'e',tInd+1] + p[:,'b',tInd+1]
             if tInd == 0:
                 return rhs
             dt = self.timeSteps[tInd]
-            return rhs + 1.0/dt*self.MfMui*u[:,'b',tInd]
+            return rhs + 1.0/dt*self.MfMui*y[:,'b',tInd]
 
         def AhCalcFields(sol, solType, tInd):
-            b = sol
+            y_b = sol
             if self.survey.nTx == 1:
-                b = mkvc(b)
-            e = self.MeSigmaI*self.mesh.edgeCurl.T*self.MfMui*b - self.MeSigmaI*p[:,'e',tInd+1]
-            return {'b':b, 'e':e}
+                y_b = mkvc(y_b)
+            y_e = self.MeSigmaI*self.mesh.edgeCurl.T*self.MfMui*y_b - self.MeSigmaI*p[:,'e',tInd+1]
+            return {'b':y_b, 'e':y_e}
 
         self.curModel = m
         return self.forward(m, AhRHS, AhCalcFields)
diff --git a/simpegEM/Tests/test_TDEM_b_DerivAdjoint.py b/simpegEM/Tests/test_TDEM_b_DerivAdjoint.py
index a7b8ea0f..9f505ce3 100644
--- a/simpegEM/Tests/test_TDEM_b_DerivAdjoint.py
+++ b/simpegEM/Tests/test_TDEM_b_DerivAdjoint.py
@@ -168,22 +168,22 @@ class TDEM_bDerivTests(unittest.TestCase):
     #     passed = Tests.checkDerivative(derChk, sigma, plotIt=False, dx=dm, num=4, eps=1e-20)
     #     self.assertTrue(passed)
 
-    # def test_Deriv_J(self):
+    def test_Deriv_J(self):
 
-    #     prb = self.prb
-    #     prb.timeSteps = [(1e-05, 10), (0.0001, 10), (0.001, 10)]
-    #     mesh = self.mesh
-    #     sigma = self.sigma
+        prb = self.prb
+        prb.timeSteps = [(1e-05, 10), (0.0001, 10), (0.001, 10)]
+        mesh = self.mesh
+        sigma = self.sigma
 
-    #     # d_sig = 0.8*sigma #np.random.rand(mesh.nCz)
-    #     d_sig = 10*np.random.rand(prb.mapping.nP)
+        # d_sig = 0.8*sigma #np.random.rand(mesh.nCz)
+        d_sig = 10*np.random.rand(prb.mapping.nP)
 
 
-    #     derChk = lambda m: [prb.survey.dpred(m), lambda mx: -prb.Jvec(sigma, mx)]
-    #     print '\n'
-    #     print 'test_Deriv_J'
-    #     passed = Tests.checkDerivative(derChk, sigma, plotIt=False, dx=d_sig, num=4, eps=1e-20)
-    #     self.assertTrue(passed)
+        derChk = lambda m: [prb.survey.dpred(m), lambda mx: prb.Jvec(sigma, mx)]
+        print '\n'
+        print 'test_Deriv_J'
+        passed = Tests.checkDerivative(derChk, sigma, plotIt=False, dx=d_sig, num=4, eps=1e-20)
+        self.assertTrue(passed)
 
     # def test_projectAdjoint(self):
     #     prb = self.prb
@@ -247,24 +247,24 @@ class TDEM_bDerivTests(unittest.TestCase):
     #     print 'I am gunna fail this one: boo. :('
     #     self.assertLess(V1/V2, 1e-6)
 
-    def test_adjointsolveAhVssolveAht(self):
-        prb = self.prb
-        mesh = self.mesh
-        sigma = self.sigma
+    # def test_adjointsolveAhVssolveAht(self):
+    #     prb = self.prb
+    #     mesh = self.mesh
+    #     sigma = self.sigma
 
-        f1 = EM.TDEM.FieldsTDEM(prb.mesh, prb.survey)
-        for i in range(1,prb.nT+1):
-            f1[:,'b',i] = np.random.rand(mesh.nF, 1)
-            f1[:,'e',i] = np.random.rand(mesh.nE, 1)
+    #     f1 = EM.TDEM.FieldsTDEM(prb.mesh, prb.survey)
+    #     for i in range(1,prb.nT+1):
+    #         f1[:,'b',i] = np.random.rand(mesh.nF, 1)
+    #         f1[:,'e',i] = np.random.rand(mesh.nE, 1)
 
-        f2 = EM.TDEM.FieldsTDEM(prb.mesh, prb.survey)
-        for i in range(1,prb.nT+1):
-            f2[:,'b',i] = np.random.rand(mesh.nF, 1)
-            f2[:,'e',i] = np.random.rand(mesh.nE, 1)
+    #     f2 = EM.TDEM.FieldsTDEM(prb.mesh, prb.survey)
+    #     for i in range(1,prb.nT+1):
+    #         f2[:,'b',i] = np.random.rand(mesh.nF, 1)
+    #         f2[:,'e',i] = np.random.rand(mesh.nE, 1)
 
-        V1 = f2.tovec().dot(prb.solveAh(sigma, f1).tovec())
-        V2 = f1.tovec().dot(prb.solveAht(sigma, f2).tovec())
-        self.assertLess(np.abs(V1-V2)/np.abs(V1), 1e-6)
+    #     V1 = f2.tovec().dot(prb.solveAh(sigma, f1).tovec())
+    #     V2 = f1.tovec().dot(prb.solveAht(sigma, f2).tovec())
+    #     self.assertLess(np.abs(V1-V2)/np.abs(V1), 1e-6)
 
     # def test_adjointGvecVsGtvec(self):
     #     mesh = self.mesh